A robust lentiviral pseudotype neutralisation assay for in-field serosurveillance of rabies and lyssaviruses in Africa

Edward Wright,Suzanne Mcnabb,Trudy Goddard,Daniel L Horton,Tiziana Lembo,Louis H Nel,Robin A Weiss,Sarah Cleaveland,Anthony R Fooks

doi:10.1016/j.vaccine.2009.09.024

Abstract

The inflexibility of existing serological techniques for detection of rabies in surveillance constrains the benefit to be gained from many current control strategies. We analysed 304 serum samples from Tanzanian dogs for the detection of rabies antibodies in a pseudotype assay using lentiviral vectors bearing the CVS-11 envelope glycoprotein. Compared with the widely used gold standard fluorescent antibody virus neutralisation assay, a specificity of 100% and sensitivity of 94.4% with a strong correlation of antibody titres (r=0.915) were observed with the pseudotype assay. To increase the assay's surveillance specificity in Africa we incorporated the envelope glycoprotein of local viruses, Lagos bat virus, Duvenhage virus or Mokola virus and also cloned the lacZ gene to provide a reporter element. Neutralisation assays using pseudotypes bearing these glycoproteins reveal that they provide a greater sensitivity compared to similar live virus assays and will therefore allow a more accurate determination of the distribution of these highly pathogenic infections and the threat they pose to human health. Importantly, the CVS-11 pseudotypes were highly stable during freeze–thaw cycles and storage at room temperature. These results suggest the proposed pseudotype assay is a suitable option for undertaking lyssavirus serosurveillance in areas most affected by these infections.

Highlights

Rabies is spreading at an alarming rate in some regions of the developing world [1,2,3]
Surveillance programs and greater access to serosurveillance techniques have resulted in the discovery of a high seroprevalence against LBV in East and West African megachiroptera [12,13] and a common presence of LBV in South African bats collected for routine surveillance [11]
We recently described the use of surrogate viruses known as lentiviral pseudotypes as replacements for live or inactivated whole virus to accurately determine anti-rabies VNAb responses in vaccine recipients

Summary

Introduction

Rabies is spreading at an alarming rate in some regions of the developing world [1,2,3]. The combination of rabies awareness campaigns, improved vaccine coverage and disease surveillance has already resulted in the successful elimi-. Infection by lyssaviruses of the other genotypes (2–7) can result in a clinical manifestation that is indistinguishable from rabies. The other genotypes are distributed geographically predominantly within African, European and Australian bat populations [5]. Isolates representing genotypes 1, 2 and 4–7 have been identified in insectivorous, fruit or vampire bats [5]. Only a few clinical isolates representing these genotypes have been identified to date [11]. Surveillance programs and greater access to serosurveillance techniques have resulted in the discovery of a high seroprevalence against LBV in East and West African megachiroptera [12,13] and a common presence of LBV in South African bats collected for routine surveillance [11]

Methods

Results

Conclusion