Atypical bovine morbillivirus infections in the Serengeti ecosystem

Lead Research Organisation: University of Glasgow
Department Name: College of Medical, Veterinary &Life Sci

Abstract

Once the scourge of European, African and Asian livestock and wild ruminants, rinderpest virus is only the second virus in history after smallpox to be eradicated globally by vaccination. Rinderpest virus (RPV) is a morbillivirus, a close relative of measles virus (MV). Rinderpest was a devastating disease, threatening both food security and the health and wellbeing of many of the poorest livestock-dependent communities in the world. The eradication of rinderpest was arguably one of the most significant global successes in veterinary medicine.

In recent years, we have developed highly sensitive and specific diagnostic tests with which we can measure morbillivirus-specific neutralising antibodies. Using these tests, we have identified sera from cattle in Northern Tanzania that display specific neutralising activity against novel cattle morbilliviruses, including canine distemper virus (CDV), peste des petits ruminants virus (PPRV) and a rinderpest-related bovine morbillivirus.

The aim of this project is to characterise novel and atypical bovine morbilliviruses circulating in Northern Tanzania. We will build upon our preliminary screening of cattle sera, focussing on a set of ~5000 cattle sera from neighbouring areas of Serengeti and Ngorongoro districts. Collected between 2010 and 2016, these sera will provide a snapshot of the prevalence of morbillivirus-specific antibodies across the region and will enable us to locate target sites for future field studies. Informed by our findings, we will collect fresh sample material from herds in villages known to harbour antibody-positive animals, generating material for virus characterisation as well as allowing assessment of their clinical significance. The samples will be screened to identify the animals with morbillivirus-specific antibodies and the corresponding blood samples and swabs screened for viral gene sequences. These analyses will reveal the origin of the antibody reactivity, the nature of the infective agent and will permit the design of a more effective diagnostic test for the virus(es).

This project will provide epidemiological and biological data to evaluate the potential threat posed by morbilliviruses in cattle. It will generate assay systems with which the viruses may be detected and inform strategies for subsequent monitoring and control. The knowledge generated by this project will counter the risk of a novel morbillivirus emerging in cattle, ensure that immunosurveillance for morbilliviruses is not undermined by misdiagnosis, while facilitating the design of future campaigns for control and eradication by vaccination.

Technical Summary

In 2015, we initiated a project to develop improved serological assays for animal morbilliviruses, assays that would be rapid and sensitive, and which would permit the distinction of diverse lineages and species of virus. The pseudotyped virus neutralisation assay (PVNA) that we developed revealed that canine distemper virus (CDV) and peste des petits ruminants virus (PPRV) were co-circulating in African livestock, wild ruminants and carnivores. During these studies, we identified samples from cattle that contained rinderpest virus (RPV)-specific antibodies. Given that the samples were collected ~12 years after the cessation of rinderpest vaccination, these findings suggest that an RPV-related bovine morbillivirus persists in the region and that multiple morbilliviruses are co-circulating in cattle.

The rinderpest eradication program was cognisant of the need for vigilance post-eradication and proposed that continued immunosurveillance would be required to prevent viral re-emergence. In this project, we will investigate the nature of the morbillivirus seropositivity in cattle. We will conduct a comprehensive serological survey of cattle across Northern Tanzania, screening for the presence of morbillivirus neutralising antibodies. Informed by these analyses, we will revisit the sites of seropositivity, collecting fresh biological specimens for additional serology and nucleic acid preparation, assessing the clinical significance of infection. Samples from confirmed seropositive animals will be used for molecular analyses, including paramyxovirus-specific quantitative PCR and deep sequencing and screening for novel viral genomes. The data generated from these analyses will enable an in-depth characterisation of the molecular, biological and clinical properties of the bovine morbilliviruses. We will ascertain the nature of the RPV-related morbilliviruses and develop bespoke PVNA-based diagnostics that will underpin enhanced immunosurveillance and vaccine development.

Planned Impact

Eradicating morbilliviruses of livestock: The FAO/OIE program to eradicate PPRV is a substantial global undertaking and millions of doses of vaccine have already been administered in Tanzania alone. Determining whether to target small ruminants only for vaccination, or whether cattle herds in neighbouring areas require to be vaccinated is a major unresolved issue. In rural Africa, cattle generally live longer than sheep and goats. Hence if cattle or other atypical host species act as viral reservoirs, sheep and goats will require repeated programs of vaccination to ensure that "herd immunity" is maintained at a sufficient level to prevent re-emergence of the virus in an immunologically naïve host population. With the co-circulation of PPRV with RPV-related morbilliviruses and canine distemper virus (CDV) in livestock and wildlife species, the potential for mis-diagnosis and ineffective vaccination is enormous. For example, an animal with prior exposure to an RPV-related morbillivirus may resist effective vaccination with an attenuated PPRV vaccination and hence be susceptible to infection when exposed to a virulent, wild-type strain of virus.
To combat such eventualities, vaccines may need to be administered to a broader range of species, or at an increased frequency of vaccination. Such extensions of existing programmes will have significant implications for the logistics of vaccine manufacture and administration. Informed decision making based on accurate diagnosis will save time, reduce costs and enhance the likelihood of success.

Animal morbillivirus vaccine development and efficacy studies: The continued circulation of morbilliviral species that are more resistant to neutralisation or which are missed by existing diagnostic tests may interfere significantly with the effectiveness of a vaccination campaign. This project will define the species of virus currently in circulation, give an accurate estimate of prevalence and provide sequence data for vaccine reinement should it prove necessary. The high sensitivity and specificity of our serological testing will greatly enhance pre- and post-vaccination sero-surveillance, demonstrating the disease-free status of livestock and the absence of infection in wildlife reservoirs.

Livestock-keeping families in affected areas: Morbilliviruses have a significant impact on herd health and productivity in developing countries. For example, there are ~37.4 million PPR-associated sheep and goat deaths each year with an annual loss of between $1.4 billion and $2.7 billion. The accurate identification of the nature of the morbilliviruses circulating in livestock will enable livestock-keepers to protect their herds more effectively and to make informed decisions about when to vaccinate, when to boost and how to avoid re-infection. Hence, livelihoods will improve and local food sources will be protected. A better understanding of virus transmission and maintenance will have additional far-reaching benefits. It will enable veterinarians and veterinary officers to communicate with livestock keepers more effectively, to explain the rationale behind vaccination as a means of eradicating disease, how this will increase productivity and benefit the community. In doing so, this will encourage better engagement with eradication programs.

Morbilliviruses as a threat to global wildlife: Our existing direct contacts with wildlife veterinarians, conservation societies and biologists have revealed that morbilliviruses present significant threats to global wildlife populations. CDV and PPRV epizootics have affected diverse species, for example gazelle, antelope, camels and buffalo have succumbed to PPRV, while CDV continues to target endangered carnivores. The co-circulation of RPV-related viruses, PPRV and CDV in wildlife may provide a reservoir of morbilliviruses capable of invading a vacated niche in livestock post-RPV eradication, or in future years post-PPRV eradication.

Publications

10 25 50
 
Description We have conducted a wide-ranging serological survey of livestock in Northern Tanzania for atypical morbillivirus infections. Our findings have demonstrated that there are at least three morbilliviruses circulating in livestock. Peste des petits ruminants virus (PPRV), a pathogen of sheep and goats is also present in a significant proportion of cattle. There is evidence of widespread exposure of cattle, sheep and goats to canine distemper virus (CDV), a pathogen normally associated with dogs. There is evidence of infection of sheep and goats with a rinderpest-related morbillivirus, a virus we identified previously in cattle. These finding suggest that multiple morbilliviruses are moving between livestock species and that their presence may influence diagnostics and vaccine efficacy.
Exploitation Route These findings constitute the first AIm of the research project and are informing our approach to Aims 2 and 3 of the project. The findings will be prepared for publication in due course.
Sectors Agriculture, Food and Drink,Healthcare,Pharmaceuticals and Medical Biotechnology

 
Description We are in the process of organising our first workshop for technicians in Tanzania, aimed at improving technical capacity building. Technicians will be trained int he techniques required for the safe handling and processing of biological samples, preparing nucleic acid for subsequent use in real time PCR -based diagnostic tests.
First Year Of Impact 2019
Sector Agriculture, Food and Drink,Healthcare,Pharmaceuticals and Medical Biotechnology
Impact Types Societal,Economic

 
Description European Medicines Agency Ad Hoc Advisory Group
Geographic Reach Europe 
Policy Influence Type Participation in a advisory committee
Impact The advisory committee was tasked with assessing the risks associated with the presence of contaminating retroviruses in feline and canine vaccines. The risks were assessed and guidelines for the Animal Healthcare Industry, the European Medicines Agency, veterinary practitioners and the public were drafted and published. The committee engaged in productive dialogue with representatives of the Animal Healthcare Industry, ensuring that vaccine products designed for use in cats and dogs met the highest possible standards of safety.
URL https://www.ema.europa.eu/documents/regulatory-procedural-guideline/cvmp-risk-management-strategy-ma...
 
Description Updating OIE Chapter 2.2.1. Biotechnology in the diagnosis of infectious diseases
Geographic Reach Multiple continents/international 
Policy Influence Type Influenced training of practitioners or researchers
 
Description Responsive mode
Amount £485,660 (GBP)
Funding ID BB/R004250/1 
Organisation Biotechnology and Biological Sciences Research Council (BBSRC) 
Sector Public
Country United Kingdom
Start 10/2017 
End 09/2020
 
Title Development of viral pseudotypes bearing morbilliviral glycoproteins 
Description We are developing and optimising assay systems with which morbilliviral glycoproteins H (hemagglutinin) and F (fusion) can be expressed on the surface of vesicular stomatitis virus (VSV) particles. The particles carry a luciferase marker gene and hence may be used to measure virus neutralising antibodies with high sensitivity and under reduced (CL2) containment. 
Type Of Material Technology assay or reagent 
Year Produced 2016 
Provided To Others? Yes  
Impact The techniques have been used to investigate the seroprevalence of morbilliviruses in livestock in Tanzania, revealing widespread infection of cattle, sheep and goats with diverse morbilliviruses. The techniques have also been used to detect low levels of neutralising antibodies in peste des petits ruminants virus (PPRV)-vaccinated cattle prior to challenge with rinderpest virus (RPV), and to measure cross-neutralisation of measles virus (MeV) by sera from goats exposed to PPRV. We have exported the technique to other laboratories in London and Thailand. 
 
Description Conducting field studies in Tanzania 
Organisation Scotland's Rural College
Country United Kingdom 
Sector Academic/University 
PI Contribution Dr Harriet Auty, EPIC, SRUC Inverness, is our collaborating partner for field studies in Tanzania. In collaboration with Dr Auty in Inverness, and Dr Tiziana Limbo at the University of Glasgow, we are conducting longitudinal studies on morbillivirus infections of livestock, including, planning, logistics, engagement with livestock keepers and veterinary officers, livestock sampling, sample processing in Tanzania and shipping to the UK for subsequent analyses.
Collaborator Contribution Working as a collaborative team, we are involved in all aspects of planning, logistics, sampling, sample processing in Tanzania and shipping to the UK for subsequent analyses.
Impact This is an ongoing collaboration, we are currently collecting and processing samples from initial field studies.
Start Year 2016
 
Description Exchange of novel hemagglutinin and fusion protein expression constructs with Pirbright 
Organisation The Pirbright Institute
Country United Kingdom 
Sector Academic/University 
PI Contribution We have prepared expression vectors bearing clones of the hemagglutinin and fusion protein genes from the four major lineages of peste des petits ruminants (PPRV) circulating globally. Similarly, we prepared H and F expression constructs from diverse global lineages of canine distemper virus (CDV), and from the virulent RBOK strain of rinderpest virus (RPV). These constructs were shared with Dr. Dalan Bailey, our collaborator at the Pirbright Institute.
Collaborator Contribution Dr. Dalan Bailey, our collaborator at the Pirbright Institute, will use the PPRV, CDV and RPV clones to investigate the virus-receptor interaction, the determinants that govern the emergence of potential zoonotic threats and the rol of escape from neutralising antibodies in driving the emergence of novel viral variants.
Impact Initial findings underpinned by this collaboration were published in Journal of Virology - https://jvi.asm.org/content/92/23/e01248-18
Start Year 2017
 
Description Screening of ruminant sera from Tanzania for morbillivirus-specific neutralising antibodies 
Organisation University of Glasgow
Department Institute of Biodiversity, Animal Health and Comparative Medicine
Country United Kingdom 
Sector Multiple 
PI Contribution We have screened sera from diverse wildlife species and domesticated livestock for morbillivirus-specific antibodies.
Collaborator Contribution Our colleagues in IBAHCM (led by Prof. Sarah Cleaveland) provide access to sera from historical and ongoing studies on a range of pathogens for morbillivirus antibody screening. They have advised on economic and cultural factors influencing the likelihood of exposure to pathogens in pastoralist communities in Tanzania. The collaboration has extended to include Dr Harriet Auty (Scotland's Rural College); Dr. Furaha Mramba, Tanzania Veterinary Laboratory; Prof. Rudovick Kazwala, Sokoine University of Agriculture; Dr. Julius Keyyu and Dr. Robert Fyumagwa, Tanzania Wildlife Research Institute. Dr. Harriet Auty is a veterinary epidemiologist investigating the dynamics, impacts and control of vector-borne diseases and zoonotic diseases of livestock. She is a research fellow with EPIC - the Scottish Government's Centre of Expertise on Animal Disease Outbreaks. Dr. Auty will lead field studies in the coming years. Prof. Sarah Cleaveland is an internationally renowned expert on rabies and zoonotic diseases. Elected a fellow of the Royal Society in 2016, she has worked extensively on the control of neglected tropical diseases in Africa, building and sustaining partnerships with African institutions that will create positive changes in the lives of disadvantaged people. Dr. Furaha Mramba, head of the Tanzania Veterinary Laboratory Agency, liaises with the Ministry of Agriculture, Livestock and Fisheries in applying results to the development of control strategies in Tanzania, and supports coordination of field work in Tanzania.
Impact This collaboration provided some of the original data that informed the development of the the pseudotype based neutralisation assay. Shared master's students have been supervised and a PhD student has been appointed under a separate funding programme. Data generated through this collaboration underpinned the successful application for follow-on funding from the BBSRC and a new sample set collected in 2016 is integral to the first year of the new study.
Start Year 2013
 
Description Laboratory techniques training session 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Visit to the Nelson Mandela African Institute of Science and Technology in Tanzania to host laboratory workshop during which local scientists learned ELISA techniques used to measure Rift Valley Fever Virus antibodies in sera.
Year(s) Of Engagement Activity 2013
 
Description Postgraduate lectures 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Delivery of postgraduate teaching on taught component of masters degree and laboratory projects on morbilliviruses.
Year(s) Of Engagement Activity 2015,2016
 
Description Social media acitvities 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Whenever significant progress is made in the research project, our findings are publicised through CVR and Pirbright social media outlets, and through our laboratory twitter account @Animal_Viruses. We direct followers to the source publication, to News articles covering the publication, and to comment articles. For example, our recent publication in Journal of Virology was discussed on the TWIV podcast (This Week In Virology).
Year(s) Of Engagement Activity 2018,2019
 
Description Undergraduate lectures 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Undergraduate students
Results and Impact The provision of research-led undergraduate lectures on morbilliviruses.
Year(s) Of Engagement Activity 2015,2016