Growth characteristics of coxsackivirus A9 grown in B vitamin deficient cells

In the early 1990’s, widespread nutritional deficiencies occurred in Cuba, resulting in epidemic optic and peripheral neuropathy. Coxsackievirus A9 and CA9‐like viruses were isolated from cerebrospinal fluid of 86% of neuropathy patients cultured. B vitamins were prominent among the nutritional deficiencies linked to the outbreak, as well as in supplements effective in treatment and prevention of the illness. Previous work in our laboratory suggests a high rate of viral mutation in CA9 strains that replicated in B vitamin deficient individuals. In order to model in culture what may have occurred in a human population, we inoculated B vitamin sufficient and deficient cells with a CA9 strain isolated during the Cuban epidemic. DBS‐FRhL‐2 cells were grown for 13 days in media without thiamine hydrochloride, riboflavin, niacinamide, pyridoxal hydrochloride, or folate. Parallel control cells were grown in normal non‐deficient media. Cell cultures were infected at day 13 with virus at a multiplicity of infection of 0.1. Virus was harvested after 40 hours of infection and titered. Subsequent passages continued in the same manner. After 5 passages, virus passed in B vitamin deficient cells exhibited altered cytopathic effect and almost 100‐fold reduction in titer compared to virus passed in B vitamin sufficient cells. The appearance of differences following 5 serial passages suggests that the virus was adapting to growth in B vitamin deficient cells, which may mimic what occurred in human populations. Thus, host cell B vitamin deficiency may profoundly affect the growth characteristics of CA9. Supported by NIH grant R01EY12310