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Characterisation of morbilliviruses isolated from Lake Baikal seals (Phoca sibirica)
L V Mamaev1, N N Denikina, S I Belikov
1Limnological Institute, Irkutsk, Russian Federation.
Abstract:
Sequence analysis of the haemagglutinin protein (H) gene of the morbillivirus (PDV-2) isolated from a Siberian seal (Phoca sibirica) during the 1987/1988 epizootic in Lake Baikal revealed that it was most closely related to two recent isolates of canine distemper virus (CDV) from Germany and different from CDV vaccines currently in use in that region. The virus continued to circulate in seals in Lake Baikal after the 1987/1988 epizootic since sera collected from culled seals in the spring of 1992 were positive in morbillivirus ELISA tests, reacting most strongly with the CDV antigen.
Insights
A novel phocine distemper virus (PDV-2) in Siberian seals was genetically similar to canine distemper virus (CDV) strains, not current vaccines. This morbillivirus continued circulating in Lake Baikal seals post-epizootic.
Area of Science:
- Veterinary Virology
- Marine Mammal Health
- Molecular Epidemiology
Background:
- Phocine distemper virus (PDV) causes significant mortality in pinnipeds.
- The 1987/1988 Lake Baikal epizootic involved a morbillivirus affecting Siberian seals (Phoca sibirica).
- Understanding the genetic relationship of circulating viruses is crucial for disease management and vaccine development.
Purpose of the Study:
- To genetically characterize the haemagglutinin (H) gene of the morbillivirus isolated from Siberian seals during the 1987/1988 epizootic.
- To compare the genetic makeup of the seal morbillivirus with known canine distemper virus (CDV) strains and vaccines.
Main Methods:
- Sequence analysis of the haemagglutinin (H) gene of the morbillivirus (PDV-2).
- Phylogenetic analysis to determine the relationship with other morbilliviruses.
- Enzyme-linked immunosorbent assay (ELISA) on sera from 1992 culled seals using CDV antigen.
Main Results:
- The PDV-2 isolate from Siberian seals was most closely related to recent German CDV isolates.
- The PDV-2 H gene sequence differed from currently used CDV vaccines.
- Morbillivirus antibodies, reacting strongly with CDV antigen, were detected in sera from seals sampled in 1992, indicating continued circulation.
Conclusions:
- The Lake Baikal seal morbillivirus (PDV-2) represents a distinct lineage closely related to CDV.
- The circulating virus in Lake Baikal seals was antigenically similar to CDV but distinct from available vaccines.
- Continuous surveillance and genetic monitoring of morbilliviruses in wildlife populations are essential.