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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR & BIOCHEMICAL DETECTION & INTERVENTION METHODS FOR BACTERIAL AND VIRAL PATHOGENS IN AQUACULTURE PRODUCTS

Location: Food Safety and Intervention Technologies

Title: Retention of Enteric Viruses by the Hemocytes of the Eastern Oyster (Crassostrea virginica)

Authors
item Ozbay, Gulnihal -
item Kingsley, David
item Provost, Keleigh -
item Anderson, Robert -

Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: July 17, 2010
Publication Date: July 17, 2010
Citation: Ozbay,G.,Kingsley,D.,Provost,K.,Anderson,R.2010.Retention of Enteric Viruses by the Hemocytes of the Eastern Oyster (Crassostrea virginica)[abstract].Institute of Food Technologists Meeting. Chicago,IL.p.1.

Technical Abstract: Shellfish are an important vector for transmission of enteric pathogens. Interventions, such as depuration, do not adequately clear enteric viruses, while fecal bacteria levels are significantly reduced. Why viruses are retained in the bivalve flesh is not well understood. We hypothesize that phagocytic blood cells (hemocytes) of the oyster play an important role for the retention of virus particles within bivalves. When hemocytes from HAV-exposed oysters were harvested and separated from the hemolymph, HAV was found to be hemocyte cell-associated. Further studies demonstrated that temporal persistence of HAV, murine norovirus (MNV) and poliovirus (PV) within hemocytes correlates with the presence of HAV in oyster meat. Transfer of hemocytes from HAV-contaminated oysters to naïve virus-free oysters results in the meat of the naive oyster testing positive for up to two weeks. Since the phagocytized virus would likely result in sequestration of viruses within the acidic phagolysome of the hemocyte, acidic pH tolerance of several viruses (HAV, MNV, PV, and feline calicvirus; FCV) was evaluated to see if acid tolerance correlates with the virus’ ability to persist within oysters. The order of persistence within oysters and the ability to survive low pH were similar; HAV persisted the longest and is most acid resistant, while FCV did not persist within oysters and is not acid tolerant. Antiviral activity of hemocytes was evaluated. No significant antiviral activity was seen after incubation of MNV with whole hemolymph, hemocytes or plasma from untreated oysters; however, these components all have strong antibacterial activity. Studies are under way to see if treatment with a beta-glucan immunostimulant commonly used in aquaculture will affect viral retention in oysters. Overall these studies suggest that hemocytes play an important role in the retention of human viruses in oyster tissues.

Last Modified: 4/16/2014
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