Replication and persistence of coxsackieviruses B3 in human fibroblasts

Although in some cases a carrier state of Coxsackieviruses in human fibroblasts was described, the persistence mechanism has remained unknown. Our results demonstrate a replication of Coxsackievirus B3 (CVB3) in diploid human fibroblasts that is dependent on the virus strain as well as on the cell line involved. Two CVB3 Nancy strains could be multiplied over more than 10 passages in cell line H, whereas CVB3 strains SH"C" and SH"W" did not longer form infectious virus following several passages in these fibroblasts. None of the CVB3 strains replicated in cell lines J and K after a few passages. These results were not influenced by variations of culture conditions such as duration of incubation (3 or 7 days), temperature (33 or 37 degrees C) or application of trypsin. In line H, only 3-5 per cent of human fibroblasts were virus-infected. This was demonstrated by 1. antigen evidence by immunofluorescence, 2. determination of infectious centres, and 3. virus reproduction in dependence on MOI of the virus. We observed a carrier state of CVB3 Nancy strains over 16 cell passages in line H fibroblasts infected once. As shown in virus passage experiments, only few cells were productively infected. An addition of specific anti-CVB3 antiserum terminated this persistent infection. Generally, no cytopathic effect was observed. However, in one case a cell destruction by CVB3 Nancy "P" at the end of the life-time of the carrier cells could be found. This virus caused a complete cytopathic effect during more than 10 passages in line H and could still be neutralized by CVB3-specific antiserum.