Genetic diversity of the Kaposi's sarcoma herpesvirus K1 protein in AIDS-KS in Zimbabwe.

BACKGROUND

Kaposi's sarcoma-associated herpesvirus (KSHV) encodes genetically diverse K1 alleles which have unique geographic distributions. Little is known about K1 genetic diversity in Zimbabwe where acquired immunodeficiency syndrome-associated KS (AIDS-KS) is epidemic.

OBJECTIVE

Evaluate K1 diversity in Zimbabwe and compare Zimbabwean K1 diversity to other areas in Africa.

STUDY DESIGN

K1 nucleotide sequence was determined for AIDS-KS cases in Zimbabwe. K1 references sequences were obtained from Genbank.

RESULTS

Among 65 Zimbabwean AIDS-KS cases, 26 (40%) were K1 subtype A and 39 (60%) were subtype B. Zimbabwean subtype A sequences grouped only with African intratype A5 variants. Zimbabwean subtype B sequences grouped with multiple intratype African variants: 26 B1 (26%), four B3 (6%) and nine highly divergent B4 (14%). Zimbabwean subtype B had a lower synonymous to nonsynonymous mutation ratio (median 0.59 versus 0.66; P=0.008) and greater distance to the most recent common ancestor (median 0.03 versus 0.009; P<0.001) compared to subtype A. Within the B subgroup, the distribution of intratype B variants differed in Zimbabwe and Uganda (P=0.004).

CONCLUSIONS

Greater positive selection and genetic diversity in K1 subtype B compared to subtype A5 exist in Zimbabwe. However, there were no significant associations between K1 subtype and the clinical or demographic characteristics of AIDS-KS cases.