HIV病毒.ppt

HIV:Human Immunodeficiency Virus
Gengfu Xiao
xiaogengfu@
Epidemiology
1980-1981: New York and California; CDC
1983-1984: Montagnier and colleagues at the Pasteur Institute; Gallo and coworkers at the NIH
Since the initial detection of the epidemic in the United States and Europe, it has grown to involve an estimated 60 million persons worldwide, with 5 million new infections per year, with epidemics expanding in south Asia and China
China also has a severe problem with up to million HIV-infected people in 2004 (prevalence rate: %). It is predicted that if nothing is done to prevent the increasing infection rate, China will have 10 million cases by 2010.
Origin of HIV
The global HIV epidemic is the result of a cross-species infection of humans by a chimpanzee lentivirus, simian immunodeficiency virus (SIVcpz), which occurred in west central Africa
SIVcpz is an asymptomatic infection in chimpanzees
Date of introduction of the M group into the human population is estimated to be around 1931, based on analysis of large numbers of sequenced HIV isolates, assuming a constant rate of evolution
This approach has been validated by essfully timing the earliest historic isolate, which was sequenced from a stored plasma sample obtained in 1959 from a person who died in Manchester, England
HIV-1 Genotypes
M (main); O (outlier); and N (non-M, non-O)
The M group of HIV-1, which includes more than 95% of the global virus isolates, consists of at least nine discrete clades or subgroups (A, B, C, D, F, G, H, J, and K) and 15 circulating binant forms (CRF)
HIV-1 group O isolates have been recovered from individuals living in Cameroon, Gabon, and Equatorial Guinea; their genomes share approximately 65% identity with group M viruses
Early in the epidemic, group O strains may have been responsible for more than 20% of HIV-1 infections in Cameroon but currently are associated with approximately only 1%
HIV-1 Genotypes
Clade A viruses, the mon HIV-1 subtype in Africa e