A buyers club or buying club is a club organized to pool members' collective buying power, enabling them to make purchases at lower prices than are generally available, or to purchase goods that might be difficult to obtain independently.
91-568: Some key examples of buyers clubs include medical purchases of rare medications for treating HIV or hepatitis C sooner, at reduced cost for patients. In many parts of the United States, Canada, and Europe, families and individuals combine their purchasing power to buy items, typically bulk-type food, in a volume that generates a discounted price from the seller. The seller saves by having only one purchase order to manage and, possibly, less packaging and delivery to deal with. The buyers benefit from
182-490: A long terminal repeat (LTR). Regions in the LTR act as switches to control production of new viruses and can be triggered by proteins from either HIV or the host cell. The Psi element is involved in viral genome packaging and recognized by gag and rev proteins. The SLIP element ( TTTTTT ) is involved in the frameshift in the gag - pol reading frame required to make functional pol . The term viral tropism refers to
273-559: A "2" (222100–272099). The "2" series BINs will be processed the same as the "51–55" series BINs are today. They became active 14 October 2016. On 23 July 2014 JSC NSPK was established in the Russian Federation. The joint stock company National System of Payment Cards (NSPK) is the operator of the Mir National Payment System. The main initiatives of NSPK are to create the national payment system infrastructure and to issue
364-500: A card number (including the initial MII digit) are known as the issuer identification number (IIN). These identify the card issuing institution that issued the card to the card holder. The rest of the number is allocated by the card issuer. The card number's length is its number of digits. Many card issuers print the entire IIN and account number on their card. In some circumstances, the issuer identification number (IIN) or bank identification number (BIN) may not be licensed directly from
455-462: A card's IIN indicates a bank in one country, while the customer's billing address is in another, the transaction may call for extra scrutiny. On 8 November 2004, Mastercard and Diners Club formed an alliance. Diners Club cards issued in Canada and the United States start with 54 or 55 and are treated as Mastercards worldwide. International cards use the 36 prefix and are treated as Mastercards in Canada and
546-535: A cell by a virion can be called "cell-free spread" to distinguish it from a more recently recognized process called "cell-to-cell spread". In cell-free spread (see figure), virus particles bud from an infected T cell, enter the blood or extracellular fluid and then infect another T cell following a chance encounter. HIV can also disseminate by direct transmission from one cell to another by a process of cell-to-cell spread, for which two pathways have been described. Firstly, an infected T cell can transmit virus directly to
637-481: A cell surface. The unusual processing and high density means that almost all broadly neutralising antibodies that have so far been identified (from a subset of patients that have been infected for many months to years) bind to, or are adapted to cope with, these envelope glycans. The molecular structure of the viral spike has now been determined by X-ray crystallography and cryogenic electron microscopy . These advances in structural biology were made possible due to
728-702: A condition in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive. Without treatment, the average survival time after infection with HIV is estimated to be 9 to 11 years, depending on the HIV subtype . In most cases, HIV is a sexually transmitted infection and occurs by contact with or transfer of blood , pre-ejaculate , semen , and vaginal fluids . Non-sexual transmission can occur from an infected mother to her infant during pregnancy , during childbirth by exposure to her blood or vaginal fluid, and through breast milk . Within these bodily fluids, HIV
819-414: A few tested specimens might provide inconclusive results because of a low quantity specimen. In these situations, a second specimen is collected and tested for HIV infection. Modern HIV testing is extremely accurate, when the window period is taken into consideration. A single screening test is correct more than 99% of the time. The chance of a false-positive result in a standard two-step testing protocol
910-457: A free trial membership being included as a "thank you" gift along with the initial purchase. The customer may not understand what was purchased or may believe that they have not authorized payment for the membership, and yet the credit card used for the initial purchase is billed for the buyer's club membership at the end of the free trial. According to Iowa Attorney General Tom Miller , "Consumers often tell us they don't recall ever having spoken to
1001-448: A human host cell when the newly formed virus particle buds from the cell. The viral envelope contains proteins from the host cell and relatively few copies of the HIV envelope protein, which consists of a cap made of three molecules known as glycoprotein (gp) 120 , and a stem consisting of three gp41 molecules that anchor the structure into the viral envelope. The envelope protein, encoded by
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#17330859968911092-568: A key step in the progression to AIDS. A number of studies with subtype B-infected individuals have determined that between 40 and 50 percent of AIDS patients can harbour viruses of the SI and, it is presumed, the X4 phenotypes. HIV-2 is much less pathogenic than HIV-1 and is restricted in its worldwide distribution to West Africa . The adoption of "accessory genes" by HIV-2 and its more promiscuous pattern of co-receptor usage (including CD4-independence) may assist
1183-413: A lower per-unit cost and, incidentally, from an increased sense of community and sharing. Bulk-food sellers often provide tools so their customers can set up community buyers' clubs. The trend for buyers' clubs, or local co-ops, accelerated starting in the 1970s. However, these groups are organic in structure, locally governed, and can come into being and go out of existence without much publicity, so there
1274-600: A more stable conformation following the NC binding, in which both the DIS and the U5:AUG regions of the gRNA participate in extensive base pairing. RNA can also be processed to produce mature messenger RNAs (mRNAs). In most cases, this processing involves RNA splicing to produce mRNAs that are shorter than the full-length genome. Which part of the RNA is removed during RNA splicing determines which of
1365-607: A national payment card, Mir. Effective 1 October 2006, Discover began using the entire 65 prefix, not just 650. Also, similar to the Mastercard/Diners agreement, China UnionPay cards are now treated as Discover cards and accepted on the Discover network. While the vast majority of Visa's account ranges describe 16 digit card numbers there are still a few account ranges (forty as of 11 December 2013) dedicated to 13 digit PANs and several (439 as of 11 December2013) account ranges where
1456-447: A number of mechanisms, including pyroptosis of abortively infected T cells, apoptosis of uninfected bystander cells, direct viral killing of infected cells, and killing of infected CD4 T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When CD4 T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections, leading to
1547-460: A strain of SIV found in sooty mangabees. Since HIV-1 is derived from SIVcpz, and HIV-2 from SIVsm, the genetic sequence of HIV-2 is only partially homologous to HIV-1 and more closely resembles that of SIVsm. Many HIV-positive people are unaware that they are infected with the virus. For example, in 2001 less than 1% of the sexually active urban population in Africa had been tested, and this proportion
1638-558: A target T cell via a virological synapse . Secondly, an antigen-presenting cell (APC), such as a macrophage or dendritic cell, can transmit HIV to T cells by a process that either involves productive infection (in the case of macrophages) or capture and transfer of virions in trans (in the case of dendritic cells). Whichever pathway is used, infection by cell-to-cell transfer is reported to be much more efficient than cell-free virus spread. A number of factors contribute to this increased efficiency, including polarised virus budding towards
1729-456: Is an adaptation for repair of genome damage, and that recombinational variation is a byproduct that may provide a separate benefit. The final step of the viral cycle, assembly of new HIV-1 virions, begins at the plasma membrane of the host cell. The Env polyprotein (gp160) goes through the endoplasmic reticulum and is transported to the Golgi apparatus where it is cleaved by furin resulting in
1820-507: Is bound with the CD4 protein, the envelope complex undergoes a structural change, exposing the chemokine receptor binding domains of gp120 and allowing them to interact with the target chemokine receptor. This allows for a more stable two-pronged attachment, which allows the N-terminal fusion peptide gp41 to penetrate the cell membrane. Repeat sequences in gp41, HR1, and HR2 then interact, causing
1911-466: Is estimated to be about 1 in 250,000 in a low risk population. Testing post-exposure is recommended immediately and then at six weeks, three months, and six months. Payment card number A payment card number , primary account number ( PAN ), or simply a card number , is the card identifier found on payment cards , such as credit cards and debit cards , as well as stored-value cards , gift cards and other similar cards. In some situations
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#17330859968912002-424: Is even lower in rural populations. Furthermore, in 2001 only 0.5% of pregnant women attending urban health facilities were counselled, tested or received their test results. Again, this proportion is even lower in rural health facilities. Since donors may therefore be unaware of their infection, donor blood and blood products used in medicine and medical research are routinely screened for HIV. HIV-1 testing
2093-464: Is high as the glycans shield the underlying viral protein from neutralisation by antibodies. This is one of the most densely glycosylated molecules known and the density is sufficiently high to prevent the normal maturation process of glycans during biogenesis in the endoplasmic and Golgi apparatus. The majority of the glycans are therefore stalled as immature 'high-mannose' glycans not normally present on human glycoproteins that are secreted or present on
2184-399: Is initially done using an enzyme-linked immunosorbent assay (ELISA) to detect antibodies to HIV-1. Specimens with a non-reactive result from the initial ELISA are considered HIV-negative, unless new exposure to an infected partner or partner of unknown HIV status has occurred. Specimens with a reactive ELISA result are retested in duplicate. If the result of either duplicate test is reactive,
2275-447: Is largely confined to West Africa . HIV is similar in structure to other retroviruses. It is roughly spherical with a diameter of about 120 nm , around 100,000 times smaller in volume than a red blood cell . It is composed of two copies of positive- sense single-stranded RNA that codes for the virus' nine genes enclosed by a conical capsid composed of 2,000 copies of the viral protein p24 . The single-stranded RNA
2366-601: Is more likely, leading to immunodeficiency. Three groups of HIV-1 have been identified on the basis of differences in the envelope ( env ) region: M, N, and O. Group M is the most prevalent and is subdivided into eight subtypes (or clades ), based on the whole genome, which are geographically distinct. The most prevalent are subtypes B (found mainly in North America and Europe), A and D (found mainly in Africa), and C (found mainly in Africa and Asia); these subtypes form branches in
2457-820: Is no precise figure for how many buyers' clubs of this sort exist or have existed. In the United Kingdom, the "Smarterbuys" scheme, which helps provide affordable loans to disadvantaged people so that they can buy essential goods, won the government 's Buy Better Together Challenge prize in 2012. The Buy Better Together Challenge was launched by the Department for Business, Innovation and Skills and Co-operatives UK in December 2011 to encourage groups of consumers to work together to negotiate discounted rates for buying goods and services in bulk. The challenge received 110 entries and seven finalists were selected. Fair Food Carlisle
2548-555: Is present as both free virus particles and virus within infected immune cells . Research has shown (for both same-sex and opposite-sex couples) that HIV is not contagious during sexual intercourse without a condom if the HIV-positive partner has a consistently undetectable viral load . HIV infects vital cells in the human immune system, such as helper T cells (specifically CD4 T cells), macrophages , and dendritic cells . HIV infection leads to low levels of CD4 T cells through
2639-412: Is tightly bound to nucleocapsid proteins, p7, and enzymes needed for the development of the virion such as reverse transcriptase , proteases , ribonuclease and integrase . A matrix composed of the viral protein p17 surrounds the capsid ensuring the integrity of the virion particle. This is, in turn, surrounded by the viral envelope , that is composed of the lipid bilayer taken from the membrane of
2730-534: Is unknown how often such mixed packaging occurs under natural conditions. Bonhoeffer et al. suggested that template switching by reverse transcriptase acts as a repair process to deal with breaks in the single-stranded RNA genome. In addition, Hu and Temin suggested that recombination is an adaptation for repair of damage in the RNA genomes. Strand switching (copy-choice recombination) by reverse transcriptase could generate an undamaged copy of genomic DNA from two damaged single-stranded RNA genome copies. This view of
2821-633: The African green monkey (SIVagm) and sooty mangabey (SIVsmm) are thought to have a long evolutionary history with their hosts. These hosts have adapted to the presence of the virus, which is present at high levels in the host's blood, but evokes only a mild immune response, does not cause the development of simian AIDS, and does not undergo the extensive mutation and recombination typical of HIV infection in humans. In contrast, when these strains infect species that have not adapted to SIV ("heterologous" or similar hosts such as rhesus or cynomologus macaques ),
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2912-541: The CCR5-Δ32 mutation are resistant to infection by the R5 virus, as the mutation leaves HIV unable to bind to this co-receptor, reducing its ability to infect target cells. Sexual intercourse is the major mode of HIV transmission. Both X4 and R5 HIV are present in the seminal fluid , which enables the virus to be transmitted from a male to his sexual partner . The virions can then infect numerous cellular targets and disseminate into
3003-445: The adsorption of glycoproteins on its surface to receptors on the target cell followed by fusion of the viral envelope with the target cell membrane and the release of the HIV capsid into the cell. Entry to the cell begins through interaction of the trimeric envelope complex ( gp160 spike) on the HIV viral envelope and both CD4 and a chemokine co-receptor (generally either CCR5 or CXCR4 , but others are known to interact) on
3094-421: The gag polyproteins still need to be cleaved into the actual matrix, capsid and nucleocapsid proteins. This cleavage is mediated by the packaged viral protease and can be inhibited by antiretroviral drugs of the protease inhibitor class. The various structural components then assemble to produce a mature HIV virion. Only mature virions are then able to infect another cell. The classical process of infection of
3185-480: The issuer identification number (IIN) sometimes referred to as the bank identification number (BIN). The remaining numbers, except the last digit, are the individual account identification number. The last digit is the Luhn check digit. IINs and PANs have a certain level of internal structure and share a common numbering scheme set by ISO/IEC 7812. The parts of the number are as follows: The first six or eight digits of
3276-514: The microtubule -based transport to the nucleus, the viral single-strand RNA genome is transcribed into double-strand DNA, which is then integrated into a host chromosome. HIV can infect dendritic cells (DCs) by this CD4-CCR5 route, but another route using mannose-specific C-type lectin receptors such as DC-SIGN can also be used. DCs are one of the first cells encountered by the virus during sexual transmission. They are currently thought to play an important role by transmitting HIV to T cells when
3367-403: The phylogenetic tree representing the lineage of the M group of HIV-1. Co-infection with distinct subtypes gives rise to circulating recombinant forms (CRFs). In 2000, the last year in which an analysis of global subtype prevalence was made, 47.2% of infections worldwide were of subtype C, 26.7% were of subtype A/CRF02_AG, 12.3% were of subtype B, 5.3% were of subtype D, 3.2% were of CRF_AE, and
3458-438: The α -chemokine receptor, CXCR4 , for entry. Dual-tropic HIV-1 strains are thought to be transitional strains of HIV-1 and thus are able to use both CCR5 and CXCR4 as co-receptors for viral entry. The α -chemokine SDF-1 , a ligand for CXCR4, suppresses replication of T-tropic HIV-1 isolates. It does this by down-regulating the expression of CXCR4 on the surface of HIV target cells. M-tropic HIV-1 isolates that use only
3549-427: The β -chemokine receptor, CCR5 , for entry and are thus able to replicate in both macrophages and CD4 T cells. This CCR5 co-receptor is used by almost all primary HIV-1 isolates regardless of viral genetic subtype. Indeed, macrophages play a key role in several critical aspects of HIV infection. They appear to be the first cells infected by HIV and perhaps the source of HIV production when CD4 cells become depleted in
3640-583: The CCR5 receptor are termed R5; those that use only CXCR4 are termed X4, and those that use both, X4R5. However, the use of co-receptors alone does not explain viral tropism, as not all R5 viruses are able to use CCR5 on macrophages for a productive infection and HIV can also infect a subtype of myeloid dendritic cells , which probably constitute a reservoir that maintains infection when CD4 T cell numbers have declined to extremely low levels. Some people are resistant to certain strains of HIV. For example, people with
3731-405: The DIS (dimerization initiation signal) hairpin is exposed. The formation of the gRNA dimer is mediated by a 'kissing' interaction between the DIS hairpin loops of the gRNA monomers. At the same time, certain guanosine residues in the gRNA are made available for binding of the nucleocapsid (NC) protein leading to the subsequent virion assembly. The labile gRNA dimer has been also reported to achieve
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3822-419: The HIV env gene, allows the virus to attach to target cells and fuse the viral envelope with the target cell's membrane releasing the viral contents into the cell and initiating the infectious cycle. As the sole viral protein on the surface of the virus, the envelope protein is a major target for HIV vaccine efforts. Over half of the mass of the trimeric envelope spike is N-linked glycans . The density
3913-441: The HIV protein-coding sequences is translated. Mature HIV mRNAs are exported from the nucleus into the cytoplasm , where they are translated to produce HIV proteins, including Rev . As the newly produced Rev protein is produced it moves to the nucleus, where it binds to full-length, unspliced copies of virus RNAs and allows them to leave the nucleus. Some of these full-length RNAs function as mRNAs that are translated to produce
4004-570: The HIV virological synapse in vivo . The many dissemination mechanisms available to HIV contribute to the virus' ongoing replication in spite of anti-retroviral therapies. HIV differs from many viruses in that it has very high genetic variability . This diversity is a result of its fast replication cycle , with the generation of about 10 virions every day, coupled with a high mutation rate of approximately 3 x 10 per nucleotide base per cycle of replication and recombinogenic properties of reverse transcriptase. This complex scenario leads to
4095-516: The LTR promoter acting by binding the TAR RNA element. The TAR may also be processed into microRNAs that regulate the apoptosis genes ERCC1 and IER3 . The rev protein (p19) is involved in shuttling RNAs from the nucleus and the cytoplasm by binding to the RRE RNA element. The vif protein (p23) prevents the action of APOBEC3G (a cellular protein that deaminates cytidine to uridine in
4186-433: The U.S.: Although IFA can be used to confirm infection in these ambiguous cases, this assay is not widely used. In general, a second specimen should be collected more than a month later and retested for persons with indeterminate western blot results. Although much less commonly available, nucleic acid testing (e.g., viral RNA or proviral DNA amplification method) can also help diagnosis in certain situations. In addition,
4277-682: The United States, IINs are also used in NCPDP pharmacy claims to identify processors, and are printed on all pharmacy insurance cards. IINs are the primary routing mechanism for real-time claims. The ISO Register of Issuer Identification Numbers database is managed by the American Bankers Association . ABA is the Registration Authority for this standard and is responsible for allocating IINs to issuers. Online merchants may use IIN lookups to help validate transactions. For example, if
4368-441: The United States, but are treated as Diners Club cards elsewhere. Diners Club International's website makes no reference to old 38 prefix numbers, and they can be presumed reissued under the 55 or 36 IIN prefix. Effective 16 October 2009, Diners Club cards beginning with 30, 36, 38 or 39 have been processed by Discover Card. On 3 November 2014, Mastercard announced that they were introducing a new series of BIN ranges that begin with
4459-515: The United States, the Federal Trade Commission (FTC) found that fraudulent or misleading buyers clubs were one of the top three types of consumer fraud in 2011, affecting about 0.6% of the US population every year. These memberships are typically sold in the course of selling another product, either with a free trial membership being a condition of making the purchase at the offered price or with
4550-409: The adaptive benefit of recombination in HIV could explain why each HIV particle contains two complete genomes, rather than one. Furthermore, the view that recombination is a repair process implies that the benefit of repair can occur at each replication cycle, and that this benefit can be realized whether or not the two genomes differ genetically. On the view that recombination in HIV is a repair process,
4641-423: The advent of AIDS. HIV-positive patients acquire an enormously broad spectrum of opportunistic infections, which was particularly problematic prior to the onset of HAART therapies; however, the same infections are reported among HIV-infected patients examined post-mortem following the onset of antiretroviral therapies. Thus, during the course of infection, viral adaptation to the use of CXCR4 instead of CCR5 may be
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#17330859968914732-403: The animals develop AIDS and the virus generates genetic diversity similar to what is seen in human HIV infection. Chimpanzee SIV (SIVcpz), the closest genetic relative of HIV-1, is associated with increased mortality and AIDS-like symptoms in its natural host. SIVcpz appears to have been transmitted relatively recently to chimpanzee and human populations, so their hosts have not yet adapted to
4823-486: The back of the card. The payment card number differs from the Business Identifier Code (BIC/ISO 9362, a normalized code—also known as Business Identifier Code, Bank International Code or SWIFT code). It also differs from Universal Payment Identification Code , another identifier for a bank account in the United States. Payment card numbers are composed of 8 to 19 digits, The leading six or eight digits are
4914-404: The card number is referred to as a bank card number . The card number is primarily a card identifier and may not directly identify the bank account number(s) to which the card is/are linked by the issuing entity. The card number prefix identifies the issuer of the card, and the digits that follow are used by the issuing entity to identify the cardholder as a customer and which is then associated by
5005-592: The cell as new virus particles that will begin the replication cycle anew. Two types of HIV have been characterized: HIV-1 and HIV-2. HIV-1 is the virus that was initially discovered and termed both lymphadenopathy associated virus (LAV) and human T-lymphotropic virus 3 (HTLV-III). HIV-1 is more virulent and more infective than HIV-2, and is the cause of the majority of HIV infections globally. The lower infectivity of HIV-2, compared to HIV-1, implies that fewer of those exposed to HIV-2 will be infected per exposure. Due to its relatively poor capacity for transmission, HIV-2
5096-470: The cell types a virus infects. HIV can infect a variety of immune cells such as CD4 T cells , macrophages , and microglial cells . HIV-1 entry to macrophages and CD4 T cells is mediated through interaction of the virion envelope glycoproteins (gp120) with the CD4 molecule on the target cells' membrane and also with chemokine co-receptors . Macrophage-tropic (M-tropic) strains of HIV-1, or non- syncytia -inducing strains (NSI; now called R5 viruses ) use
5187-454: The collapse of the extracellular portion of gp41 into a hairpin shape. This loop structure brings the virus and cell membranes close together, allowing fusion of the membranes and subsequent entry of the viral capsid. After HIV has bound to the target cell, the HIV RNA and various enzymes, including reverse transcriptase, integrase, ribonuclease, and protease, are injected into the cell. During
5278-556: The companies, and they don't understand how they can be charged when they have not given the company their credit card number ." Sometimes, a wide variety of products are promised at a discount, and then once the fee is paid the products are unavailable or not as advertised. This is particularly true for travel-related buying clubs. HIV The human immunodeficiency viruses ( HIV ) are two species of Lentivirus (a subgroup of retrovirus ) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS),
5369-447: The development of AIDS. HIV is a member of the genus Lentivirus , part of the family Retroviridae . Lentiviruses have many morphologies and biological properties in common. Many species are infected by lentiviruses, which are characteristically responsible for long-duration illnesses with a long incubation period . Lentiviruses are transmitted as single-stranded , positive- sense , enveloped RNA viruses . Upon entry into
5460-577: The development of stable recombinant forms of the viral spike by the introduction of an intersubunit disulphide bond and an isoleucine to proline mutation ( radical replacement of an amino acid) in gp41. The so-called SOSIP trimers not only reproduce the antigenic properties of the native viral spike, but also display the same degree of immature glycans as presented on the native virus. Recombinant trimeric viral spikes are promising vaccine candidates as they display less non-neutralising epitopes than recombinant monomeric gp120, which act to suppress
5551-792: The disease and drug developments, and became an important source of AIDS treatment education and advocacy. An example of an AIDS buyers club was drawn to wider prominence with the 2013 film release Dallas Buyers Club . In response to the high price of modern direct-acting antiviral (DAA) treatments for hepatitis C , the FixHepC buyers club was set up by James Freeman and his father John Freeman in Australia in 2015 in order to help individual patients obtain legal access to generic versions of sofosbuvir , daclatasvir , and ledipasvir . At EASL International Liver Congress, Dr. Freeman presented data showing how generic versions are as effective as branded products. In
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#17330859968915642-431: The generation of many variants of HIV in a single infected patient in the course of one day. This variability is compounded when a single cell is simultaneously infected by two or more different strains of HIV. When simultaneous infection occurs, the genome of progeny virions may be composed of RNA strands from two different strains. This hybrid virion then infects a new cell where it undergoes replication. As this happens,
5733-576: The generation of recombinational variation would be a consequence, but not the cause of, the evolution of template switching. HIV-1 infection causes chronic inflammation and production of reactive oxygen species . Thus, the HIV genome may be vulnerable to oxidative damage , including breaks in the single-stranded RNA. For HIV, as well as for viruses in general, successful infection depends on overcoming host defense strategies that often include production of genome-damaging reactive oxygen species. Thus, Michod et al. suggested that recombination by viruses
5824-552: The genetic information that is transmitted from parental to progeny genomes. Viral recombination produces genetic variation that likely contributes to the evolution of resistance to anti-retroviral therapy . Recombination may also contribute, in principle, to overcoming the immune defenses of the host. Yet, for the adaptive advantages of genetic variation to be realized, the two viral genomes packaged in individual infecting virus particles need to have arisen from separate progenitor parental viruses of differing genetic constitution. It
5915-415: The immune response to target epitopes. The RNA genome consists of at least seven structural landmarks ( LTR , TAR , RRE , PE, SLIP, CRS, and INS), and nine genes ( gag , pol , and env , tat , rev , nef , vif , vpr , vpu , and sometimes a tenth tev , which is a fusion of tat , env and rev ), encoding 19 proteins. Three of these genes, gag , pol , and env , contain information needed to make
6006-518: The integrated DNA provirus is transcribed into RNA. The full-length genomic RNAs (gRNA) can be packaged into new viral particles in a pseudodiploid form. The selectivity in the packaging is explained by the structural properties of the dimeric conformer of the gRNA. The gRNA dimer is characterized by a tandem three-way junction within the gRNA monomer, in which the SD and AUG hairpins , responsible for splicing and translation respectively, are sequestered and
6097-438: The issuer can mix 13 and 16 digit card numbers. Visa's VPay brand can specify PAN lengths from 13 to 19 digits and so card numbers of more than 16 digits are now being seen. Switch was re-branded as Maestro in mid-2007. In 2011, UK domestic Maestro (formerly Switch) was aligned with the standard international Maestro proposition with the retention of a few residual country specific rules. EMV Certification requires acceptance of
6188-404: The issuing entity with the customer's designated bank accounts. In the case of stored-value type cards, the association with a particular customer is only made if the prepaid card is reloadable. Card numbers are allocated in accordance with ISO/IEC 7812 . The card number is typically embossed on the front of a payment card, and is encoded on the magnetic stripe and chip, but may also be imprinted on
6279-523: The issuing network (such as Mastercard or Visa). Obtaining an IIN/BIN number can be costly, time consuming and demand intensive operational burdens on in-house regulatory and compliance teams. For this reason, some new card programmes may use a 'BIN sponsor', in which case the IIN/BIN number is effectively sub-licensed from a scheme regulated entity. This is known as BIN sponsorship, and is a popular way for financial institutions to fast-track access to market. In
6370-410: The patient. Macrophages and microglial cells are the cells infected by HIV in the central nervous system . In the tonsils and adenoids of HIV-infected patients, macrophages fuse into multinucleated giant cells that produce huge amounts of virus. T-tropic strains of HIV-1, or syncytia -inducing strains (SI; now called X4 viruses ) replicate in primary CD4 T cells as well as in macrophages and use
6461-406: The remaining 5.3% were composed of other subtypes and CRFs. Most HIV-1 research is focused on subtype B; few laboratories focus on the other subtypes. The existence of a fourth group, "P", has been hypothesised based on a virus isolated in 2009. The strain is apparently derived from gorilla SIV (SIVgor), first isolated from western lowland gorillas in 2006. HIV-2's closest relative is SIVsm,
6552-425: The reverse transcriptase, by jumping back and forth between the two different RNA templates, will generate a newly synthesized retroviral DNA sequence that is a recombinant between the two parental genomes. This recombination is most obvious when it occurs between subtypes. The closely related simian immunodeficiency virus (SIV) has evolved into many strains, classified by the natural host species. SIV strains of
6643-516: The single-stranded viral DNA and/or interferes with reverse transcription ). The vpr protein (p14) arrests cell division at G2/M . The nef protein (p27) down-regulates CD4 (the major viral receptor), as well as the MHC class I and class II molecules. Nef also interacts with SH3 domains . The vpu protein (p16) influences the release of new virus particles from infected cells. The ends of each strand of HIV RNA contain an RNA sequence called
6734-412: The site of cell-to-cell contact, close apposition of cells, which minimizes fluid-phase diffusion of virions, and clustering of HIV entry receptors on the target cell towards the contact zone. Cell-to-cell spread is thought to be particularly important in lymphoid tissues , where CD4 T cells are densely packed and likely to interact frequently. Intravital imaging studies have supported the concept of
6825-673: The specimen is reported as repeatedly reactive and undergoes confirmatory testing with a more specific supplemental test (e.g., a polymerase chain reaction (PCR), western blot or, less commonly, an immunofluorescence assay (IFA)). Only specimens that are repeatedly reactive by ELISA and positive by IFA or PCR or reactive by western blot are considered HIV-positive and indicative of HIV infection. Specimens that are repeatedly ELISA-reactive occasionally provide an indeterminate western blot result, which may be either an incomplete antibody response to HIV in an infected person or nonspecific reactions in an uninfected person. HIV deaths in 2014 excluding
6916-553: The structural proteins Gag and Env. Gag proteins bind to copies of the virus RNA genome to package them into new virus particles. HIV-1 and HIV-2 appear to package their RNA differently. HIV-1 will bind to any appropriate RNA. HIV-2 will preferentially bind to the mRNA that was used to create the Gag protein itself. Two RNA genomes are encapsidated in each HIV-1 particle (see Structure and genome of HIV ). Upon infection and replication catalyzed by reverse transcriptase, recombination between
7007-496: The structural proteins for new virus particles. For example, env codes for a protein called gp160 that is cut in two by a cellular protease to form gp120 and gp41. The six remaining genes, tat , rev , nef , vif , vpr , and vpu (or vpx in the case of HIV-2), are regulatory genes for proteins that control the ability of HIV to infect cells, produce new copies of virus (replicate), or cause disease. The two tat proteins (p16 and p14) are transcriptional transactivators for
7098-427: The target cell surface. Gp120 binds to integrin α 4 β 7 activating LFA-1 , the central integrin involved in the establishment of virological synapses , which facilitate efficient cell-to-cell spreading of HIV-1. The gp160 spike contains binding domains for both CD4 and chemokine receptors. The first step in fusion involves the high-affinity attachment of the CD4 binding domains of gp120 to CD4. Once gp120
7189-413: The target cell, the viral RNA genome is converted (reverse transcribed) into double-stranded DNA by a virally encoded enzyme, reverse transcriptase , that is transported along with the viral genome in the virus particle. The resulting viral DNA is then imported into the cell nucleus and integrated into the cellular DNA by a virally encoded enzyme, integrase , and host co-factors . Once integrated,
7280-414: The two HIV envelope glycoproteins, gp41 and gp120 . These are transported to the plasma membrane of the host cell where gp41 anchors gp120 to the membrane of the infected cell. The Gag (p55) and Gag-Pol (p160) polyproteins also associate with the inner surface of the plasma membrane along with the HIV genomic RNA as the forming virion begins to bud from the host cell. The budded virion is still immature as
7371-484: The two genomes can occur. Recombination occurs as the single-strand, positive-sense RNA genomes are reverse transcribed to form DNA. During reverse transcription, the nascent DNA can switch multiple times between the two copies of the viral RNA. This form of recombination is known as copy-choice. Recombination events may occur throughout the genome. Anywhere from two to 20 recombination events per genome may occur at each replication cycle, and these events can rapidly shuffle
7462-570: The viral DNA into the host cell's genome is carried out by another viral enzyme called integrase . The integrated viral DNA may then lie dormant, in the latent stage of HIV infection. To actively produce the virus, certain cellular transcription factors need to be present, the most important of which is NF- κ B (nuclear factor kappa B), which is upregulated when T cells become activated. This means that those cells most likely to be targeted, entered and subsequently killed by HIV are those actively fighting infection. During viral replication,
7553-536: The virus in its adaptation to avoid innate restriction factors present in host cells. Adaptation to use normal cellular machinery to enable transmission and productive infection has also aided the establishment of HIV-2 replication in humans. A survival strategy for any infectious agent is not to kill its host, but ultimately become a commensal organism. Having achieved a low pathogenicity, over time, variants that are more successful at transmission will be selected. The HIV virion enters macrophages and CD4 T cells by
7644-425: The virus is captured in the mucosa by DCs. The presence of FEZ-1 , which occurs naturally in neurons , is believed to prevent the infection of cells by HIV. HIV-1 entry, as well as entry of many other retroviruses, has long been believed to occur exclusively at the plasma membrane. More recently, however, productive infection by pH -independent, clathrin-mediated endocytosis of HIV-1 has also been reported and
7735-463: The virus may become latent , allowing the virus and its host cell to avoid detection by the immune system, for an indeterminate amount of time. The virus can remain dormant in the human body for up to ten years after primary infection; during this period the virus does not cause symptoms. Alternatively, the integrated viral DNA may be transcribed , producing new RNA genomes and viral proteins, using host cell resources, that are packaged and released from
7826-403: The virus to evade the body's immune system. The reverse transcriptase also has ribonuclease activity that degrades the viral RNA during the synthesis of cDNA, as well as DNA-dependent DNA polymerase activity that creates a sense DNA from the antisense cDNA. Together, the cDNA and its complement form a double-stranded viral DNA that is then transported into the cell nucleus . The integration of
7917-537: The virus. This virus has also lost a function of the nef gene that is present in most SIVs. For non-pathogenic SIV variants, nef suppresses T cell activation through the CD3 marker. Nef 's function in non-pathogenic forms of SIV is to downregulate expression of inflammatory cytokines , MHC-1 , and signals that affect T cell trafficking. In HIV-1 and SIVcpz, nef does not inhibit T-cell activation and it has lost this function. Without this function, T cell depletion
8008-475: The whole organism. However, a selection process leads to a predominant transmission of the R5 virus through this pathway. In patients infected with subtype B HIV-1, there is often a co-receptor switch in late-stage disease and T-tropic variants that can infect a variety of T cells through CXCR4. These variants then replicate more aggressively with heightened virulence that causes rapid T cell depletion, immune system collapse, and opportunistic infections that mark
8099-503: Was awarded the runner-up prize for a scheme which uses buying groups to provide workplaces with a weekly supply of food from local businesses. In the early days of the HIV/AIDS epidemic, AIDS buyers clubs became important as a means of obtaining medications not yet approved by the FDA that members thought might be useful in treating HIV and opportunistic infections . The first and largest of these
8190-448: Was recently suggested to constitute the only route of productive entry. Shortly after the viral capsid enters the cell, an enzyme called reverse transcriptase liberates the positive-sense single-stranded RNA genome from the attached viral proteins and copies it into a complementary DNA (cDNA) molecule. The process of reverse transcription is extremely error-prone, and the resulting mutations may cause drug resistance or allow
8281-548: Was the People With AIDS Health Group (PWA Health Group), founded in 1986 by Thomas Hannan , Joseph Sonnabend , and Michael Callen . AIDS buyers clubs distributed such unapproved drugs as ribavirin , dextran sulfate, and DCNB (dinitrochlorobenzene) , as well as cheaper pirated versions of zidovudine (AZT), which was the first antiretroviral drug that was FDA-approved for the treatment of HIV and AIDS in 1987. AIDS buyers clubs also distributed information about
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