Studies on penaeid shrimp viruses and cell cultures

The present study dealt with three aspects of shrimp virology: (a) development of penaeid cell culture; (b) characterization of two shrimp viruses, the yellow-head virus (YHV) and the Chinese baculovirus (CBV); and (c) evaluation of an enzyme-immunoassay protocol for the detection of a shrimp virus in Hawaiian shrimp farms.; Primary shrimp lymphoid cell cultures were successfully prepared by tissue explant method using Leibovitz Medium-15 supplemented with fetal bovine serum, shrimp head extract, epidermal growth factor, and interleukin-2. The primary cell cultures could be maintained for 3 weeks or longer and were susceptible to YHV and CBV, but not to Rhabdovirus of penaeid shrimp (RPS). This led to the development of quantal assay (50% tissue culture infectious dose, TCID{dollar}sb{lcub}50{rcub}){dollar} protocols for YHV and CBV.; Transfection of primary lymphoid cells using simian virus-40 tumor (T)-antigen oncogene resulted in two transformants: OKTr-1 and OKTr-23. These transformed cell lines exhibited characteristics typical of transformed phenotype such as altered morphology, less anchorage dependence, reduced serum requirement, heteroploidy, etc. They have also been successfully passaged beyond the primary stage. Unlike the normal lymphoid cells, the transformed cells were not susceptible to any of the shrimp, fish (infectious hematopoietic necrosis virus), and mammalian (vesicular stomatitis virus) viruses tested. In fact, they had antiviral activity the mechanism of which remains to be defined.; Characterization of two of the most virulent viruses (YHV and CBV) that affected the shrimp aquaculture industry was done based on their physical, chemical, biological and serological properties. YHV was provisionally identified as a rhabdovirus and CBV was identified as a non-occluded baculovirus. Rabbit polyclonal antisera against these viruses were generated and used to develop solid-phase enzyme immunoassay protocols for the detection of YHV and CBV in shrimp populations.; The nitrocellulose-enzyme immunoassay/streptavidin-biotin amplification (NC-EIA/SAB) protocol and the immunofluorescence antibody technique (IFA) were evaluated for the detection of RPS in Hawaiian shrimp farms over a period of two years. The RPS was detected in 47% of apparently healthy samples tested regardless of the metamorphic stage of the shrimp.; The development of a convenient in vitro system to grow shrimp viruses, isolation and characterization protocols for shrimp viruses, and immunoassay detection protocols will facilitate studies on shrimp viruses and consequently develop prophylactic strategies for disease prevention.