Abstract
The human displacement and sexual behavior are the main factors driving the HIV-1 pandemic to the current profile. The intrinsic structure of the HIV transmission among different individuals has valuable importance for the understanding of the epidemic and for the public health response. The aim of this study was to characterize the HIV-1 subtype B (HIV-1B) epidemic in South America through the identification of transmission links and infer trends about geographical patterns and median time of transmission between individuals. Sequences of the protease and reverse transcriptase coding regions from 4,810 individuals were selected from GenBank. Maximum likelihood phylogenies were inferred and submitted to ClusterPicker to identify transmission links. Bayesian analyses were applied only for clusters including ≥5 dated samples in order to estimate the median maximum inter-transmission interval. This study analyzed sequences sampled from 12 South American countries, from individuals of different exposure categories, under different antiretroviral profiles, and from a wide period of time (1989–2013). Continentally, Brazil, Argentina and Venezuela were revealed important sites for the spread of HIV-1B among countries inside South America. Of note, from all the clusters identified about 70% of the HIV-1B infections are primarily occurring among individuals living in the same geographic region. In addition, these transmissions seem to occur early after the infection of an individual, taking in average 2.39 years (95% CI 1.48–3.30) to succeed. Homosexual/Bisexual individuals transmit the virus as quickly as almost half time of that estimated for the general population sampled here. Public health services can be broadly benefitted from this kind of information whether to focus on specific programs of response to the epidemic whether as guiding of prevention campaigns to specific risk groups.
Highlights
Today, nearly one million individuals are infected by HIV-1 in South America and approximately 35,000 individuals die per year victims of the symptoms of AIDS [1]
Among 7,600 pol sequences available in public databases, 4,810 HIV-1 subtype B isolates from South American countries were selected to set up a dataset for the identification of transmission links (S1 Table)
Due to the large area occupied by Brazil in South America, samples isolated in this country were identified by specific state of sampling (Fig 1)
Summary
Nearly one million individuals are infected by HIV-1 in South America and approximately 35,000 individuals die per year victims of the symptoms of AIDS [1]. Through the genetic and evolutionary relationship these epidemiological chains allow the inference of social contacts between individuals and provide a way to reconstruct the main transmission links involved in the spread of the virus in a certain place [6,12,13] These findings improves the correlation of local HIV epidemic with transmission pathway, drug resistance, risk behavior and cluster size and may influence the direction focus of public campaigns to specific populations aiming to reduce the rate of transmissions and delaying the increase in the number of new infection cases [14]. Addressing the specific issues within local epidemics is crucial to a greatly improvement in the HIV-1 epidemic [2]
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