Predictions of Future HIV Infection by Subtype and Circulating Recombinant Form

SUMMARY Twenty three million people have died as a result of the onset of acquired immunodeficiency syndrome, better known as AIDS, caused by the HIV virus. This tells us that AIDS is one of the worst diseases in existence. Sub-Saharan Africa had a total of 25 million HIV infections in 2000 and 29 million infections in 2002. Globally, the world contained a total of 36 million HIV infections in 2000 and 42 million in 2002 [6]. The subtypes causing HIV infections in Sub-Saharan Africa will be the most common subtypes of HIV that cause HIV infection throughout the globe in the future since these subtypes account for 70 percent of global infections. Phylogenetic analysis of HIV-1 strains has revealed that they could be divided into groups due to their high genetic diversity. Group M infections cause greater than 95 percent of infections across the globe [5]. Group M is especially genetically diverse thus it is broken into subtypes including A, B, C, D, E, F, G, H, I, and J. There are also circulating recombinant forms which are the combinations of these subtypes. Some of the recombinants include types AE, AG, AB, DF, BC, CD, AE, GJ, and others [5]. The different subtypes are generally geographically distinct with Sub Saharan Africa containing all known HIV-1 subtypes [5]. The HIV subtypes are associated with specific modes of HIV infection and transmission rates. Subtype B is associated with homosexual intercourse and intravenous drug use, whereas subtypes A, E, and C are associated with heterosexual transmission [1]. This finding coupled with the fact that subtype A has increased from 28 percent to nearly 35 percent of all cases is significant since it suggests that AIDS is being transmitted more through heterosexual sexual contact. Also, according to some studies, subtype A is most transmissible [7]. This leads us to believe that subtype A infections will continue to increase at a high rate in the future and possibly cause the majority of HIV infections within ten years. All the data for comparing numbers of total worldwide HIV infection was obtained from the UNAIDS 2000 and 2002 reports on the epidemic [6]. Subtype data for the year 2000 was obtained from an article on global HIV subtypes [4]. The subtype data for the year 2002 was obtained from the Los Alamos National Laboratory [2]. The sample sizes for the 2000 and 2002 data on HIV subtypes can be viewed to show the accuracy of each years subtype approximations by region (table 1). Significant changes are viewed when considering the proportion of HIV infections caused by each subtype between the years 2000 and 2002 (figure 1). 1 Student 2 Assistant Professor