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Abstracts
Workgroup: Frontiers in Disease Research
Epizootiology and pathogenicity of Perkinsus species.
Principal Investigator(s):
Gerardo R. Vasta, Center of Marine Biotechnology, Baltimore, MD, vasta@umbi.umd.edu
Co-Investigator(s):
J.A.F. Robledo
Funding Period: 2001-03
- Sampling throughout summer and fall months of 2002.
- Eleven sites, four areas with both C. virginica and M. mercenaria sampled.
- Over 1800 individuals sampled: C. virginica, M. mercenaria, M. arenaria, G. demissa.
- To date, over 1200 PCR analyses conducted: Generic (Perkinsus), P. marinus, and P. andrewsi specific. Strain-specific analysis of P. marinus also conducted on selected amplicons.
- Preliminary data shows high prevalence of P. marinus in oyster at several sites, with moderate prevalence in others. In M. mercenaria, P. marinus prevalence lower.
- Dual infections (oyster) with both P. marinus and P. andrewsi in more than one site sampled.
- An indication that both type I and type II strains of P. marinus may infect a single individual oyster
- At least two individuals testing positive with the generic primer set did not generate products with either P. marinus or P. andrewsi primers , suggesting that an additional Perkinsus sp. was present. Generic amplicons from these individuals are being sequenced.
IMPACTS and/or BENEFITS:
Having developed the highly specific and sensitive molecular tools to discern which species of Perkinsus is present in an individual, we are now applying them to field situations.
These results improve significantly on the FTM method of assessing Perkinsus sp prevalence. They confirm suspicions that:
- not all Perkinsus infections are due to P. marinus
- more than one than one species or strain can infect an individual.
Additional information such as that provided in this study will help managers of oyster stocks along the east coast. For example, Perkinsus infections shown to be due to a non-P. marinus species may pose less of a threat to oysters, and thus be managed differently, from those P. marinus infections of known pathogenicity.
There may be additional, as yet undescribed, species of Perkinsus along the Atlantic coast.
PROJECT PUBLICATIONS:
Coss, C.A., Robledo, J.A.F., RuÌz, G.M., Vasta, G.R. 2001. Description of Perkinsus andrewsi n. sp. isolated from the Baltic clam (Macoma balthica) by characterization of the ribosomal RNA locus, and development of species-specific PCR-based diagnostic assay. Journal of Eukaryotic Microbiology. 48: 52-61.
Robledo, J.A.F., Nunez, P.A., Cancela, M.L., Vasta, G.R. 2002. Development of an in vitro clonal culture and characterization of the rDNA locus of Perkinsus atlanticus, a protistan parasite of the clam Tapes decussatus. Journal of Eukaryotic Microbiology. 49: 414-422.
Pecher, W.T., Robledo, J.A.F., Vasta, G.R. Identification of an additional rRNA fragment encoded by Perkinsus andrewsi genome. In Preparation.
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