Cell-fusion assay for the detection of rubella virus in Vero cells.

BACKGROUND AND

OBJECTIVES

Rubella virus (RV) produces a subtle and slow-developing cytopathic effect in Vero cells that is difficult to recognize, especially at low multiplicities of infection. In order to facilitate the detection of RV in cell culture, we standardized a low-pH virus-mediated cell-fusion assay.

STUDY

DESIGN

The incubation periods, temperatures, pH and multiplicity of infection were established. The specificity of the method was tested by immunofluorescence assay and cell-fusion inhibition by specific sera.

RESULTS

Six days post infection, Vero cells were treated for 5 min with fusion medium. After that, monolayers were incubated with medium at neutral pH for 16 h and then stained. Gigantic cells with multiple nuclei were observed.

CONCLUSIONS

The method allowed the observation of unequivocal images that are easier to recognize than the cytopathic effect caused by RV in the same cell line. At the same time, the method is simple, accessible and shown to be specific to demonstrate the replication of several strains and isolates of RV in Vero cells.