Epidemiology and Genetic Variability of HHV-8/KSHV among Rural Populations and Kaposi's Sarcoma Patients in Gabon, Central Africa. Review of the Geographical Distribution of HHV-8 K1 Genotypes in Africa

Abstract

Human herpesvirus 8 (HHV-8) is the etiological agent of all forms of Kaposi's sarcoma (KS). K1 gene studies have identified five major molecular genotypes with geographical clustering. This study described the epidemiology of HHV-8 and its molecular diversity in Gabon among Bantu and Pygmy adult rural populations and KS patients. Plasma antibodies against latency-associated nuclear antigens (LANA) were searched by indirect immunofluorescence. Buffy coat DNA samples were subjected to polymerase chain reaction (PCR) to obtain a K1 gene fragment. We studied 1020 persons; 91% were Bantus and 9% Pygmies. HHV-8 seroprevalence was 48.3% and 36.5% at the 1:40 and 1:160 dilution thresholds, respectively, although the seroprevalence of HHV-8 is probably higher in Gabon. These seroprevalences did not differ by sex, age, ethnicity or province. The detection rate of HHV-8 K1 sequence was 2.6% by PCR. Most of the 31 HHV-8 strains belonged to the B genotype (24), while the remaining clustered within the A5 subgroup (6) and one belonged to the F genotype. Additionally, we reviewed the K1 molecular diversity of published HHV-8 strains in Africa. This study demonstrated a high seroprevalence of HHV-8 in rural adult populations in Gabon and the presence of genetically diverse strains with B, A and also F genotypes.

Keywords: HHV-8; KSHV; epidemiology; genetic variability; rural populations Gabon; serology.

Figure 1

HHV-8 serological and molecular results in five studied provinces in Gabon.

Figure 2

Phylogenetic analysis of the 31 new Kaposi’s sarcoma-associated herpesvirus (KSHV)/HHV-8 sequences. Phylogenetic comparisons were performed with the 689 nucleotide long K1 gene fragment obtained from 153 KSHV/HHV-8 isolates, including the 31 sequences generated in this study (in red) and 122 previously published sequences. The phylogeny was derived by the maximum likelihood (ML) method with the GTR model. Horizontal branch lengths are drawn to scale, with the bar indicating 0.02 nucleotide replacements per site. The maximum posterior probabilities were calculated and reported on the branches with threshold value ≥0.75. * Two strains characterized from South Africa (KS55 and KS137) are not yet molecularly classified [34].

Figure 3

Map of Africa indicating the distribution of HHV-8 genotypes.