On the origin of South America HIV-1 C epidemic

Abstract

In a recent AIDS issue two articles present sequence analysis to trace the origin of HIV-1 clade C in South America. The authors correctly point out that the density of clade C infection in south Brazil and its phylogenetic relationship to most isolates observed elsewhere in South America places south Brazil as its probable origin. When tracing the origin of the C viruses circulating in Brazil both groups focused on phylogenic relationships of available/analyzable material. Although reported in the Epidemiology/Social sector the authors disconnect their findings to potential social and cultural determinants of HIV dissemination factors that may actually have played a major role in the introduction of HIV-1 clade C in Brazil. Although the precise African origin of the variant is not known it was first observed in Ethiopia but it is observed along with other variants in many countries of central and east Africa. It is conceivable that the variant migrated southwards through highland areas (including Burundi and Kenya the putative origin ascribed by each group to the South America and Brazilian clade C epidemic) to dominate the epidemic in the south of the continent. Mozambique is one of the countries in the south of Africa where clade C is predominant. In 1975 Mozambique declared its independence from Portugal and Frelimo a left-oriented liberation movement took hold of the government. Its support to liberation movements at South Africa and Rhodesia (now Zimbabwe) resulted in an armed rebel movement supported by the white-ruled neighboring countries causing a civil war that was associated with an exodus of most of the Portuguese community and Mozambicans of Portuguese heritage. Brazil a former Portuguese colony has a large community of Portuguese descendants a fact that may have facilitate a temporary or permanent destiny for some of these emigrants. According to the official Brazilian demographic data center (IBGE) the number of conceded residency for Portuguese nationals surged five-fold in 1975 returning to 1974 levels by 1981. In some areas of the south of Brazil as in the coast of the state of Santa Catarina Portuguese descendents are specially noted. Coincidentally this area includes cities with the highest proportions of clade C infection. Available molecular data may not provide sufficient support for a direct link of the two epidemics and apart from a threonine at codon 12 most amino acid signatures listed by Bello et al. [1] are not commonly observed among Mozambique sequences available at GenBank. However these isolates are recent (1999-2004) and may not reflect the variants circulating in late 1970s. An evolving virus in distinct ethnic groups may make the task of tracing its origins and evolution difficult especially when based exclusively on available most of the time fragmental sequence information. The relationship of Mozambique to Brazil through a Portuguese connection placed the area as the most feasible origin for the Brazilian clade C epidemic. Social and cultural determinants and tangibility of potential routes of dissemination should be incorporated into these studies to allow a more precise picture of HIV epidemic dynamics. (full-text)