816a Multiple human herpesvirus 8 infection C G Teo*1, M Al-Bayari2, R D Cook2, T A Hodgson2, S R Porter2, E Borgstein3, E M Molyneux3 1Virus Reference Division, PHLS Central Public Helath Laboratory, London, UK; 2Eastman Institute for Oral Hlth Care Scis, University College London, UK; and 3College of Medicine, University of Malawi, Blantyre, Malawi
Humans are not thought to be able to support multiple infection by the virus, as evidenced by studies reporting failure to detect >1 HHV-8 strain in a given host. Such studies have, however, been performed among Western male homosexuals, who would have acquired infection sexually and after childhood. In HHV-8-endemic regions in which the general population is exposed to HHV-8 at early age, the situation with multiple infection might well be different. Having previously studied the extent of HHV-8 carriage in Malawian KS patients and their first-degree relatives, we examined for intra-person variation in nucleotide sequences among HHV-8 subgenomic DNA amplified from these individuals. Twenty-two KS patients and 67 of their relatives were enrolled (55% male; 79% HHV-8-seropositive; 40% HIV-1-seropositive; age range 2- 43 y) from whom mouth rinses, throat gargles, palatal scrapes and blood were taken. Variation was first sought by examining length and restriction fragment-length polymorphisms in an~ 1800-bp segment amplified from the internal repeat domain of ORF 73; of 12 people in whom >1 sample yielded positiive amplification; only the samples of one person displayed polymorphisms. Direct nucleotide sequencing of a 211-bp segment from the relatively conserved ORF 26 was then conducted: in 14 people from whom >1 sample yielded positive amplification, intra-person sequences in 7 were non-identical; sequences from one person belonged to different genotypes. Studies of a 246-bp segment in ORF K1, encompassing the hypervariable locus (variable region 1) were then conducted, which revealed more dramatic results: in 24 people from whom >1 sample yielded positive amplification, direct sequencing of the amplicons showed that intra-person sequences in 19 were non-identical; intra-person sequences from 10 people segregated to 2 different genotypes and those from one person to 3 different genotypes. The ORF K1 amplicons were then cloned, and whether these varied in sequence on an intra-person basis was evaluated by denaturing gel gradient electrophoresis and nucleotide sequencing. Such analyses confirmed that ORF K1 sequences could indeed vary widely between blood and oral samples, and even between different oral samples taken from the same person. It is concluded that people living in HHV-8-endemic regions can be multiply infected by the virus. Such a finding has important implications for future epidemiological studies of, and design of vaccines against the virus.