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.
Highlights
Once the scourge of European, African and Asian livestock and wild ruminants, rinderpest virus (RPV) is only the second virus in history after smallpox to be eradicated by vaccination
Neutralising antibody titres were measured in sera from cattle infected previously [23] with either PPRV/Ivory Coast/89 (IC89, wild type lineage 1), PPRV/Nigeria/75/1 (N75, vaccine lineage 2), PPRV/Sungri/96 (S96, vaccine lineage 4) or the Plowright vaccine strain of RPV (RBOK)
Sera were screened for ability to neutralize pseudotypes bearing the glycoproteins of the widely used PPRV vaccine strain N75, four field strains representative of lineages 1– 4 (Senegal 1969, Benin 2010, Kenya 2011 and Ethiopia 2010), and RPV Kabete O
Summary
Once the scourge of European, African and Asian livestock and wild ruminants, rinderpest virus (RPV) is only the second virus in history after smallpox to be eradicated by vaccination. Morbillivirus, a close relative of measles virus (MeV) and peste des petits ruminants (PPRV). PPR is being considered for global eradication by vaccination [1]. PPRV causes a devastating disease in small ruminants, threatening both food security and the livelihoods of smallholders [2,3]. PPR has been selected as a top priority disease to be addressed by the World Organization for Animal Health (OIE), with a global plan for eradication by 2030 [4]
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