Factors influencing the natural history of HIV-1 infection

HIV natural history may be influenced by geography, socioeconomic factors, age, gender, and characteristics of the virus and host. A better understanding of the natural history of HIV epidemics in different locations and among different groups will allow for intervention strategies better suited to the region and population in question. As HAART scale-up is proceeding globally, natural history benchmarks are necessary to judge success of newly introduced HIV treatment programs. While much work has already been done to describe the natural history of HIV infection in previously healthy adults, further investigation is required to better predict the progression of disease in other groups (Chinese population, children, HIV infected pregnant women and co-infected patients). With a high burden of B/C recombinant virus and the possibility of unique host genetic factors, and with a large number of HIV patients now co-infected with hepatitis B or C, tuberculosis, or malaria, further HIV natural history research in China is required. While methods exist to determine viral and host factors likely to influence natural history, only some such as coreceptor tropism testing are available for routine clinical use in the developed world, and all are far from available in the developing world. Cheaper techniques or surrogates may be investigated to determine likely natural history in resource limited settings to better plan therapy. Consensus definitions for progression groups must be created so that research from different centers can be more easily compared and so that separate natural history models can be created for each group. Further research may yield focused treatment approaches for different progression groups. Existing studies of long-term nonprogressors have made exciting findings about mutations. CCR5 protective mutations, however, are largely limited to Caucasian populations. Few studies of long-term nonprogressors have been done in Asia raise the possibility that there exist polymorphisms presented only in Asian populations that would have gone undetected by previous work. Therefore, countries such as China should start programs to identify long-term nonprogressors and start conducting studies to look for protective genotypes. As investigation of genetic variation of host and virus matures, discoveries of polymorphisms that influence survival are being used deliberately rather than blindly to select targets for future drug development. A deeper understanding of the factors which influence the natural history of HIV disease may lead to the ability to predict individual HIV susceptibility, disease progression risk, and identify the best time to initiate antiretroviral therapy. This knowledge would allow for better population-level as well as individually-tailored prevention and treatment measures.