Title: Mechanisms of viral persistence within bivalves Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: December 17, 2010
Publication Date: N/A
Technical Abstract: Fecal bacteria and waterborne enteric viruses bioconcentrate within bivalve shellfish. However while bacteria are readily purged, viruses tend to be retained within shellfish when bivalves are depurated. The US. Department of Agriculture Seafood Safety Laboratory has recently demonstrated that phagocytic blood cells (hemocytes) of the oysters play an important role in retention of virus particles within bivalves. Research suggests that bioconcentrated viruses are phagocytized and sequestered within the intracellular phagolysosomes. Evidence for this is multifold. First, hepatitis A virus (HAV) was found to be associated with hemocytes harvested and separated from the hemolymph of HAV-exposed oysters. Second, transfer of hemocytes from HAV-contaminated oysters to naïve virus-free oysters results in the meat of the naïve oyster testing HAV-positive for up to three weeks. Evaluation of the temporal persistence of HAV, murine norovirus (MNV) and poliovirus (PV) within hemocytes correlates with the presence of these viruses in oyster meat. Since phagocytosis probably results in sequestration of virions within the acidic phagolysosome of the hemocyte, acidic pH tolerance of several viruses (HAV, MNV, PV, and feline calicvirus; [FCV]) was evaluated to determine if acid tolerance correlates with the virus’ ability to persist within oysters. The degree of viral persistence within oysters and their ability to survive low pH were similar: HAV persisted the longest and was most acid resistant, MNV and PV were less tolerant of acidic pH and persisted to a lesser degree than HAV, while FCV did not persist within oysters and is not acid tolerant.