Enhanced immunosurveillance for animal morbilliviruses using vesicular stomatitis virus (VSV) pseudotypes

Abstract

The measurement of virus-specific neutralising antibodies represents the “gold-standard” for diagnostic serology. For animal morbilliviruses, such as peste des petits ruminants (PPRV) or rinderpest virus (RPV), live virus-based neutralisation tests require high-level biocontainment to prevent the accidental escape of the infectious agents. In this study, we describe the adaptation of a replication-defective vesicular stomatitis virus (VSVΔG) based pseudotyping system for the measurement of neutralising antibodies against animal morbilliviruses. By expressing the haemagglutinin (H) and fusion (F) proteins of PPRV on VSVΔG pseudotypes bearing a luciferase marker gene, neutralising antibody titres could be measured rapidly and with high sensitivity. Serological responses against the four distinct lineages of PPRV could be measured simultaneously and cross-neutralising responses against other morbilliviruses compared. Using this approach, we observed that titres of neutralising antibodies induced by vaccination with live attenuated PPRV were lower than those induced by wild type virus infection and the level of cross-lineage neutralisation varied between vaccinates. By comparing neutralising responses from animals infected with either PPRV or RPV, we found that responses were highest against the homologous virus, indicating that retrospective analyses of serum samples could be used to confirm the nature of the original pathogen to which an animal had been exposed. Accordingly, when screening sera from domestic livestock and wild ruminants in Tanzania, we detected evidence of cross-species infection with PPRV, canine distemper virus (CDV) and a RPV-related bovine morbillivirus, suggesting that exposure to animal morbilliviruses may be more widespread than indicated previously using existing diagnostic techniques.

Identifying Age Cohorts Responsible for Peste Des Petits Ruminants Virus Transmission among Sheep, Goats, and Cattle in Northern Tanzania

“…Our study made several assumptions including the following: PPRV endemicity in Tanzania; a positive cELISA result indicates past PPRV exposure and current protection; a negative cELISA result indicates no past exposure and current susceptibility; that the BDSL cELISA kit was suitable for testing cattle samples; and that cross-reactivity with rinderpest or rinderpest-like viruses [47] was not expected in our samples given the sampling date and methods used to develop the cELISA kit. These assumptions are the same as those for the catalytic model with the assumption of constant age and have been discussed as reasonable first approximations for understanding PPRV transmission dynamics in previous work [19].…”

Identifying age cohorts responsible forPeste des petits ruminantsvirus transmission among sheep, goats, and cattle in northern Tanzania

“…Our study made several assumptions including: PPRV endemicity in Tanzania; age-stratified mixing of animals; a positive cELISA result indicates past PPRV exposure and current protection; a negative cELISA result indicates no past exposure and current susceptibility; that the BDSL cELISA kit was suitable for testing cattle samples; and that cross-reactivity with rinderpest or rinderpest-like viruses [40] was not expected in our samples given the sampling date and methods used to develop the cELISA kit. These assumptions (except mixing) are the same as those for the catalytic model with the assumption of constant age and have been discussed as reasonable first approximations to understanding PPRV transmission dynamics in previous work [19].…”

Future research to underpin successful peste des petits ruminants virus (PPRV) eradication

“…The development of the pseudotype-based assay for neutralizing antibodies highlights a hitherto unexplored aspect of 'gold-standard' live virus-based VNTs. Morbillivirus infections may induce cross-neutralizing antibodies, and hence the detection of a neutralizing antibody titre in cattle against PPRV by live virus-based VNT is not conclusive evidence of PPRV infection; the animal may have been exposed to PPRV, RPV or CDV, all of which may induce anti-PPRV neutralizing or cross-neutralizing antibodies [70,71]. The recent development of a helper cell-dependent recombinant PPRV has also yielded a promising, yet biosafe, source of viral antigen for future diagnostics, since this system produces replication-incompetent virus [72].…”

“…CDV can rapidly adapt to use the human form of the morbillivirus receptor (SLAMF1) in vitro [86], raising concerns about the ease with which these viruses can effectively jump hosts. Indeed, serological responses to CDV were described recently in Tanzanian cattle [71]. In addition, a new spectrum of previously uncharacterized morbilliviruses has been identified in global bat and rodent populations [87], as well as a specific new morbillivirus in domestic cats [88].…”