Distinct distribution of rare us kshv genotypes in south texas. Implications for kshv epidemiology and evolution

PURPOSE: Kaposi's sarcoma-associated herpesvirus (KSHV, or human herpesvirus 8) is etiologically associated with Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL). Although previous studies have assessed the geographic distribution of KSHV genotypes, the molecular epidemiology of KSHV remains largely unknown. The purpose of the present study was to examine the genotypes of KSHV isolates from KS patients in South Texas.METHODS: Eighteen KSHV isolates from 16 KS and 1 PEL patients in South Texas were collected between 1996 and 1998 and analyzed for KSHV subtypes by PCR sequencing of ORFK1 gene and KS330 fragment, and by PCR of ORFK15 gene. DNA sequences were aligned with known sequences and KSHV subtypes were assigned based on sequence variations.RESULTS: Of 18 KSHV isolates, 13 exhibited C subtype, and 5 exhibited A subtype in ORF K1 gene. ORF K15 genotyping showed that 10 of the isolates exhibited M form, of which 9 had C3 subtype. A unique C subtype isolate was found and classified as C6 clade. All of the M form KSHV isolates were found among KS patients over 50 years of age. Conversely, all KS patients under 40 years of age had only the P form KSHV isolates.CONCLUSIONS: In South Texas there is a distinct distribution of C3/M KSHV isolates, which are rarely found in other US regions (1 of 29). The C3/M KSHV genotype is more prevalent in HIV-negative elderly KS patients while the P-form of KSHV is more common among many young AIDS-KS patients.