Analysis of enterovirus sequences recovered from the cerebrospinal fluid of patients with epidemic neuropathy

An outbreak of a previously unknown disease, termed epidemic neuropathy (EN), occurred in Cuba between 1991 and 1993. Although nutritional and oxidative stress in the population were rapidly associated with the disease, several findings were not compatible with such stress being the only cause. In the search for biological factors, samples of the cerebrospinal fluid (CSF) from patients with EN were studied and found to have a slowly progressing cytopathic effect (CPE) on VERO cells. Although the results of several studies indicate the presence of enteroviruses, the CPE and other physico-chemical characteristics are not typical of these viruses. Viral sequences have now been amplified from patients' CSF, using oligonucleotide primers homologous to the enterovirus 5' non-coding region. The sequences of the amplified region showed a high degree of variability (7%-69%) when compared with the coxsackievirus (Cox)A9 Griggs used as the reference strain. Furthermore, sequences differing by > 55% (58%-70%) were isolated from a single individual. These results indicate the generation in stressed individuals of enterovirus quasispecies with altered biological properties, and these could have played a major role in the neurological injury of EN.