Establishment and application of a noval CVS-11 pseudovirus-based assay for detection of neutralizing antibody against rabies virus

Objective To establish a CVS-11 pseudovirus particles (pp)-based assay for detection of neutralizing antibody against rabies virus. Methods An improved rapid fluorescence focus inhibition test (RFFIT) for detection of neutralizing antibody against rabies virus (RVNA) was established based on the CVS-11 pseudovirus expressing a luciferase reporter gene. Forty-six human serum samples were analyzed with the improved RFFIT and the results were compared with those by using standard RFFIT. Moreover, the improved RFFIT was used to detect the titers of RVNA in 91 serum samples collected from pet dogs and pet-breeders in Beijing. Results The coincidence rate of the improved RFFIT and the standard RFFIT was 100% regarding to the analysis of 46 human serum samples and 5 negative reference serum samples. Moreover, the RVNA titers of all serum samples obtained with CVS-11 pseudovirus-based assay showed a significant high correlation with those obtained with standard RFFIT (n=46, r=0.94, P<0.000 1). All of the 91 serum samples collected from pet dogs and pet-breeders in Beijing were positive for RVNA as indicated by the improved RFFIT with a mean titer of 33.01 IU/ml. Conclusion We established an improved RFFIT based on the CVS-11 pp expressing luciferase reporter gene, which might be used as a reliable alternative RFFIT for measuring RVNA titer. Analysis of the 91 serum samples collected in Beijing with the improved RFFIT showed that all samples were positive for RVNA. Key words: Rabies virus neutralizing antibody (RVNA); RFFIT; CVS-11 strain; Pseudovirus particle (pp)