Virology of Malignant Brain Tumours

Glioblastoma multiforme is the most common and most aggressive type of primary malignant brain tumour, accounting for 52 % of all primary brain tumour cases and 20 % of all intracranial tumours. Evidence for a viral cause of glioblastoma has been postulated, possibly SV40 or more likely cytomegalovirus (CMV). A viral cause is difficult to substantiate, since CMV infection is so common and malignant brain tumours are so rare. One possible basis for a CMVglioblastoma association may be the hit-andrun hypothesis. CMV might be capable, under certain conditions, of acting as a cell mutagen. Age at infection may be one of these conditions, since the incidence of both glioblastoma multiforme and CMV infection are related to socioeconomic status. CMV infection in early childhood, more common in lower socioeconomic groups, may be protective against glioblastoma multiforme, whereas CMV infection in later childhood or adulthood may be a risk factor for glioblastoma. If so, glioblastoma occurrence would resemble paralytic polio, where low socioeconomic status, poor hygiene, and early infection are protective.