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Characterisation of African isolates of rinderpest virus
H M Wamwayi1, M Fleming, T Barrett
1National Veterinary Research Centre, Muguga, Kikuyu, Kenya.
Abstract:
Isolates of rinderpest virus (RPV) recovered from outbreaks of the disease in Kenya and Southern Sudan between 1986 and 1993 were compared to each other and to earlier isolates from East and West Africa. The recent isolates were mildly pathogenic for susceptible cattle and thus resembled other mild strains of RPV recovered from cattle and wildlife in East Africa more than 30 years ago. Monoclonal antibody analysis using a panel of 12 anti-RPV haemagglutinin protein-specific antibodies (mAbs) revealed that individual isolates were distinguishable. However, the panel of mAbs could not be used to relate the isolates on the basis of their pathogenicity or geographic origin. Immunoprecipitation of the virus-induced proteins from infected Vero cells, followed by SDS-polyacrylamide gel electrophoresis, showed that the recent mild RPV isolates from eastern Africa were closely related to each other and to their contemporary isolates from Nigeria and Egypt, but they were distinct from another mild isolate recovered from the region three decades ago. Two distinct lineages of African RPV isolates were identified by sequencing a region of the genome around the proteolytic enzyme cleavage site of the fusion protein from the old and new isolates. One lineage, which included virus isolates recovered from East and West Africa during the 1960s, showed a closer phylogenetic relationship to Asian and Middle Eastern RPV isolates. The other lineage consisted mainly of isolates recovered from East, West and North Africa between 1983 and 1993. The results showed that there was co-circulation of two different lineages of RPV in Nigeria during the epizootics of the 1980s.
Insights
Recent rinderpest virus (RPV) isolates from East Africa showed mild pathogenicity, resembling older strains. Genetic analysis revealed two distinct RPV lineages circulating in Africa, with evidence of co-circulation in Nigeria.
Area of Science:
- Veterinary Virology
- Molecular Epidemiology
- Animal Health
Background:
- Rinderpest virus (RPV) causes a devastating disease in cattle and wildlife.
- Understanding RPV genetic diversity is crucial for disease control and eradication efforts.
- Previous studies have characterized RPV strains from various African regions.
Purpose of the Study:
- To compare recent RPV isolates from Kenya and Southern Sudan with earlier African isolates.
- To investigate the genetic relationships and evolutionary lineages of African RPV strains.
- To assess the utility of monoclonal antibodies and molecular techniques for RPV strain differentiation.
Main Methods:
- Monoclonal antibody (mAb) analysis targeting RPV haemagglutinin protein.
- Immunoprecipitation and SDS-PAGE to analyze virus-induced proteins.
- Genome sequencing of a specific region around the fusion protein cleavage site.
Main Results:
- Recent RPV isolates were mildly pathogenic and resembled older mild strains from East Africa.
- mAb analysis distinguished individual isolates but did not correlate with pathogenicity or origin.
- Genetic sequencing identified two distinct African RPV lineages, with evidence of co-circulation in Nigeria during the 1980s.
- One lineage showed closer phylogenetic ties to Asian and Middle Eastern RPV, while the other comprised more recent African isolates.
Conclusions:
- Two distinct lineages of RPV have been circulating in Africa, with evidence of contemporary co-circulation.
- Molecular techniques, particularly genome sequencing, are valuable tools for tracing RPV evolution and epidemiology.
- Further research is needed to understand the implications of these distinct lineages for RPV control strategies.