The crystal structure of San Miguel sea lion virus type 5 and the possible association of caliciviruses to spontaneous abortions in terrestrial animals

Crystallizing a virus can be difficult and not always successful. Forty-eight salts, buffers, and precipitating agents were used in the hanging drop preparations in attempts to crystallize the San Miguel sea lion virus type 5 (SMSV-5). The first attempt resulted in 22 of the 48 solutions forming a precipitate. The second attempt was rerun at 25°C rather than 5°C but crystals were not detected and the project was ended. A second project was an attempt to associate caliciviruses with spontaneous abortions in terrestrial animals. The first of four steps, the fluorescent antibody technique was performed. The fluorescent antibody technique can be used to indicate caliciviral presence in tissue samples. Monoclonal antibodies are prepared by injecting mice with a known calicivirus. The immune system of the mice makes specific antibodies in response to the virus. These antibodies are then extracted and purified. The tissue samples are smeared on a microscope slide and the cells adhere through charge-charge interactions. Fluorescein isothiocyanate is a fluorescent tag that uses a carbon on a carboxyl group to bind to a nitrogen on an amino group of an antibody. Antibodies with tags then attach to viruses in the tissue samples. Fluorescent tags illuminate the monoclonal antibody bound to a specific epitope when viewed under a fluorescent microscope. Particular wavelengths excite the fluorescent tags so they can be seen; a fluorescent green indicates a positive test. Thirty-three batches of tissue samples were prepared and tested for caliciviruses. Sixteen gave a positive fluorescence indicating the presence of the virus.