Rabies vaccine response in companion animals: Comparative evaluation of VSV-based pseudovirion neutralization test (PVNT) and rapid fluorescent focus inhibition test (RFFIT).

Abstract

Rabies is a fatal but vaccine-preventable zoonotic disease. Global elimination of rabies necessitates multisectoral coordination and transboundary action involving mass animal vaccinations in endemic areas. The current assays for analysing seroconversion against rabies vaccines have limitations for large-scale use due to need for higher bio-containments, low-throughput and a high cost. Here, we report the feasibility of an alternative assay for detecting rabies neutralizing antibodies in vaccinated animals. This pseudovirus neutralization test (PVNT) based on vesicular stomatitis virus (VSV) platform employs secreted alkaline phosphatase (SEAP) as a reporter. The assay replaces the use of live rabies virus with single-round infectious pseudovirions as well as fluorescent microscopy in conventional neutralizing assays such as fluorescent antibody virus neutralization assay (FAVN)/ rapid fluorescent focus inhibition test (RFFIT) with an ELISA reader. We subjected a total of 60 serum samples from vaccinated dogs and cats to both RFFIT and PVNT. The results showed excellent concordance, with the PVNT showing a sensitivity of 93.8 % and specificity of 100 %. Receiver Operator Characteristics (ROC) analysis indicated a high accuracy (area under the curve >0.9) and a kappa value of 0.848 indicating comparable performances of PVNT and RFFIT. Our results show that PVNT can serve as a suitable alternative to traditional live-virus-based neutralization assays for efficacy analysis of animal rabies vaccination.