1395577

Question: Part VII -Societal Implications of HIV Protection Since this study, much has been learned about t…


Part VII -Societal Implications of HIV Protection Since this study, much has been learned about the mechanisms of protection against HIV Here are some highlights. Super T Helper Cells In sexually transmitted HIV, the M-strain HIV-1 is the infectious agent 90% of the time (Ahmad, 2002) Thus, in most infections, the CD4 and CCRs proteins are used by HIV to gain entry into T,, and infect the person Most of the individuals that are resistant through a Super T Helper Cells mechanism harbor the same mutation in their CCR gene. This is a deletion of 3a nucleotides that causes a frameshift in the reading sequence (Liu et al., 1996). Consequently. the cells of these individuals harbor no functional CCRs protein. This does not appear to have any effec predominantly in populations of European decent, on the health of individuals. Since chis mutation is found and since the mutation is first thought to have appeared pulation around 7oo years, it has been hypothesized that the mutation confers resistance to Yersinia tation confers resistance to smallpox, and others still that this allele has spread in the population pestis, the infectious agent of the bubonic plague (Martinson ct al., 1997). Others have suggested that the CCRs mu through neutral evolution (Sabeti et al., 200s). In populations of northern European descent, the frequency for CCRS 32 homozygous individuals is 1-3%, for heterozygotes it is about 14%, and for homozygote wild rype it is 83% (Sampson et al., 1996: Martinson et al., 1997) Recent studies have shown that individuals homozygous for the CCRs mutation are more prone to West Nile Virus infection (Glass et al., 2006). In addition, the lack of CCRs protein makes mice more prone to hepatitis infection (Jefferys, 2006). These findings suggest that CCRs might have a role in fighting other types of infections. This is an interesting finding. particularly in light of the fact that some experimental HIV therapies try to inhibit the expression of the CCRs protein in healthy individual As you probably have guessed from your answer to the questions in the previous section, some homozygous CCRsA32 individuals have tested positive for HIV infection (Biti et al. 1997: OBrien et al., 1997). Question . It is a relatively simple procedure to test the genotype of a person at the CCRs gene to determine whether they have the CCRs432 mutation. Should a person wishing to have their genotype tested be lowed to do so? What are the arguments for and against genotype testing of the CCRs gene Super Cytotoxic T Cells Looking back to Figure 1 of Paxtons paper (Part IV of this case study). it seems that subjects EU4. 9. 11 12, 17, 19,and 23 remained HIV negative despite repeated exposed to the virus by a mechanism that did not involve Super child, health care workers, and Kenyan prostitures, all of which sustained repeated exposure. but who remained uninfected (Rowland-Jones et al., 1993: Pinto et al, 199s: Rowland-Jones et al., 1998). While luck may have played a part, the studies revealed that such individuals had unusual HIV-specific T cell activity. In fact, in the case of the immune Nairobi sex workers, it seems that their T, are more active respond to different signals. and are involved in the production of more interferon molecules than normal (Kaul et al, 2000; Kaul et al., 200ta; Kebba et al., 2004: Alimonti et al. 2006). Interferons are proteins released by an infected cell to warn other cells of the infection. The warned cells then take defensive measures r T Helper Cells. In fact, starting in the carly 1990s, there were reports of an exposed

Show transcribed image text

Part VII -Societal Implications of HIV Protection Since this study, much has been learned about the mechanisms of protection against HIV Here are some highlights. Super T Helper Cells In sexually transmitted HIV, the M-strain HIV-1 is the infectious agent 90% of the time (Ahmad, 2002) Thus, in most infections, the CD4 and CCRs proteins are used by HIV to gain entry into T,, and infect the person Most of the individuals that are resistant through a "Super T Helper Cells" mechanism harbor the same mutation in their CCR gene. This is a deletion of 3a nucleotides that causes a frameshift in the reading sequence (Liu et al., 1996). Consequently. the cells of these individuals harbor no functional CCRs protein. This does not appear to have any effec predominantly in populations of European decent, on the health of individuals. Since chis mutation is found and since the mutation is first thought to have appeared pulation around 7oo years, it has been hypothesized that the mutation confers resistance to Yersinia tation confers resistance to smallpox, and others still that this allele has spread in the population pestis, the infectious agent of the bubonic plague (Martinson ct al., 1997). Others have suggested that the CCRs mu through neutral evolution (Sabeti et al., 200s). In populations of northern European descent, the frequency for CCRS 32 homozygous individuals is 1-3%, for heterozygotes it is about 14%, and for homozygote wild rype it is 83% (Sampson et al., 1996: Martinson et al., 1997) Recent studies have shown that individuals homozygous for the CCRs mutation are more prone to West Nile Virus infection (Glass et al., 2006). In addition, the lack of CCRs protein makes mice more prone to hepatitis infection (Jefferys, 2006). These findings suggest that CCRs might have a role in fighting other types of infections. This is an interesting finding. particularly in light of the fact that some experimental HIV therapies try to inhibit the expression of the CCRs protein in healthy individual As you probably have guessed from your answer to the questions in the previous section, some homozygous CCRsA32 individuals have tested positive for HIV infection (Biti et al. 1997: O'Brien et al., 1997). Question . It is a relatively simple procedure to test the genotype of a person at the CCRs gene to determine whether they have the CCRs432 mutation. Should a person wishing to have their genotype tested be lowed to do so? What are the arguments for and against genotype testing of the CCRs gene Super Cytotoxic T Cells Looking back to Figure 1 of Paxton's paper (Part IV of this case study). it seems that subjects EU4. 9. 11 12, 17, 19,and 23 remained HIV negative despite repeated exposed to the virus by a mechanism that did not involve "Super child, health care workers, and Kenyan prostitures, all of which sustained repeated exposure. but who remained uninfected (Rowland-Jones et al., 1993: Pinto et al, 199s: Rowland-Jones et al., 1998). While luck may have played a part, the studies revealed that such individuals had unusual HIV-specific T cell activity. In fact, in the case of the immune Nairobi sex workers, it seems that their T, are more active respond to different signals. and are involved in the production of more interferon molecules than normal (Kaul et al, 2000; Kaul et al., 200ta; Kebba et al., 2004: Alimonti et al. 2006). Interferons are proteins released by an infected cell to warn other cells of the infection. The warned cells then take defensive measures r T Helper Cells." In fact, starting in the carly 1990s, there were reports of an exposed

(Visited 3 times, 1 visits today)