Detection of avian oncogenic Marek's disease herpesvirus DNA in human sera

The avian herpesvirus Marek's disease virus (MDV) has a worldwide distribut ion and is responsible for T-lymphoma in chickens. The question as to wheth er MDV poses a public health hazard to humans was first raised when the vir us was isolated in 1967. However, no irrefutable results have been obtained in immunological and virological studies. We used a nested-PCR to detect M DV DNA in human serum samples. A total of 202 serum samples from individual s exposed and not exposed to poultry was tested by nested-PCR for a target sequence located in the MDV gD gene. The assay system was specific and sens itive, making it possible to detect a single copy of the target sequence. F orty-one (20%) of the 202 serum samples tested positive for MDV DNA. The pr evalence of MDV DNA was not significantly different in the group exposed to poultry and the group not exposed to poultry. There was also no difference due to age or sex. Alignment of the 41 gD sequences amplified from human s era with eight gD sequences amplified from MDV-infected chicken sera showed a maximum nucleotide divergence of 1.65%. However, four 'hot-spot' mutatio n sites were identified, defining four groups. Interestingly, two groups co ntained only human MDV-gD sequences. The status of the MDV genome detected in human blood is discussed.