Abstract
Infectious diseases have the potential to act as strong forces for genetic selection on the populations they affect. Human immunodeficiency virus (HIV) is a prime candidate to impose such genetic selection owing to the vast number of people it infects and the varying susceptibility of different human leucocyte antigen (HLA) types to HIV disease progression. We have constructed a model of HIV infection that differentiates between these HLA types, and have used reported estimates of the number of people infected with HIV and the different rates of progression to acquired immunodeficiency syndrome (AIDS) to provide a lower bound estimate on the length of time it would take for HIV to impose major genetic change in humans. We find that an HIV infection similar to that currently affecting sub-Saharan Africa could not yet have caused more than a 3 per cent decrease in the proportion of individuals who progress quickly to disease. Such an infection is unlikely to cause major genetic change (defined as a decrease in the proportion of quickly progressing individuals to under 50 per cent of their starting proportion) until 400 years have passed since HIV emergence. However, in very severely affected populations, there is a chance of observing such major genetic changes after another 50 years.
Highlights
Human immunodeficiency virus (HIV) has had a dramatic effect on population age structure and life expectancy in the developing world (Pope & Haase 2003)
MODELLING APPROACH To find an estimate for how quickly HIV could remove a certain allele from the human population, we assumed that individuals possessing such an allele progress to acquired immunodeficiency syndrome (AIDS) at a significantly faster Proc
Our analysis suggests that HIV has had an enormous impact on the sub-Saharan African population, it could not yet have wiped out an entire subset of this population owing to their faster progression to AIDS and death
Summary
Human immunodeficiency virus (HIV) has had a dramatic effect on population age structure and life expectancy in the developing world (Pope & Haase 2003). A relationship between human leucocyte antigen (HLA) type and progression towards AIDS and death has been shown in a number of studies. It is likely that prolonged exposure to HIV at high levels of infection could cause selection for protective HLA alleles and against alleles that speed progression towards AIDS and death. Given the severity of the HIV epidemic, it is possible that the virus has already exerted a strong selective pressure, and so altered the ratios of certain alleles within the human population. We analyse whether, given the known growth of HIV, it is possible that HIV has already caused significant selection against HLA types that enhance disease progression and death
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