Estudo epidemiológico da infecção por herpesvírus 8 humano (HHV-8) em população indígena da Amazônia brasileira / Epidemiological study of Human herpesvirus 8 infection (HHV-8) in the Amerindian population from Brazilian Amazon

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The human herpesvirus 8 (HHV-8) is endemic in Africa and Amerindian populations from Amazon region. The infection in those populations occurs during childhood and, in Africa, involves a close contact in intrafamilial environment. Several studies confirm the geographical distribution of different subtypes of HHV-8, and the subtype E is typical of the Amerindian population. Objectives: 1. To characterize the HHV-8 subtypes circulating in Amerindian population from Brazilian Amazon, based on the analysis of ORF K1 region of the virus. 2. To construct a phylogenetic tree of viral subtypes found among Amerindians 3. To compare by phylogenetic methods the subtypes found in Mapuera Amerindians with the subtypes prevalent in others Amerindians populations of Brazil and South America 4. To determine the substitution rate of VR1 region of HHV-8 for the sequences obtained in the present study 5. To estimate the date of entry of the viruses in the Mapuera population 6. To investigate the dynamic of transmission of the virus in the intrafamilial environment 7. To investigate if there is a correlation between susceptibility to HHV-8-infection and HLA class I (A and B) and II (DQB1 and DRB1) alleles. Patients and methods: The seroprevalence of HHV-8 infection in a sample of the indigenous population of the Brazilian Amazon was carried out using IFA to detect antibodies to latent (LANA) and lytic phase antigens of HHV-8. Phylogenetic analysis of the sequences was performed by using the DNA extracted from samples of saliva, using a nested PCR to amplify the hypervariable regions VR1/ VR2 of HHV-8. Estimation of the substitution rate of HHV-8 nucleotides was performed by using the method of distance and the Bayesian technique. Estimates of the time of the most recent common ancestor (TMRCA) for all samples studied were done by using the BEAST program. HLA typing of positive and negative subjects for HHV-8 infection was performed by using the PCR-SSO technique. Results: The overall HHV-8 seroprevalence was 75.3% (399/530). There was a positive correlation between soropositivity of children and maternal seropositivity. The only viral subtype found was subtype E. The substitution rate of HHV-8 using the VR1 region was estimated around 6x10-4 substitutions per site per year (s / s / y). By using this rate of substitution, the TMRCA of the Mapuera viruses sequences was estimated to be around 138 years. There was no correlation between susceptibility to HHV-8-infection and HLA class I or II alleles. Conclusions: The population studied is endemic for HHV-8 infection. The infection occurs mainly in childhood, by horizontal, nonsexual transmission, probably by saliva. As in endemic populations of Africa, the soropositvity of children is positively correlated with the seropositivity of the mothers. In agreement with previous reports, the subtype E was the only HHV-8 subtype found in Mapuera Amerindians. Our data suggest that the VR1 gene region of HHV-8 evolves with a rate of 6x10-4 substitutions per site per year (s / s / y), which results in a time of the most recent common ancestor for Mapuera HHV-8 sequences of 138 years. There was no correlation between susceptibility to HHV-8-infection and HLA class I or II alleles.

ASSUNTO(S)

epidemiologia molecular herpesvirus humano 8 evolução molecular epidemiology indigenous population tipagem de hla estudos soroepidemiológicos human herpesvirus 8 (hhv-8) hla typing evolution seroprevalence

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