UC Davis School of Veterinary Medicine

School of Veterinary Medicine

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Research Accomplishments


RinderpestRinderpest is a viral disease of ruminants with greater than 95% morbidity and mortality. We have cloned the cDNA of the nucleocapsid (N) gene of the virulent Kabete O strain of rinderpest virus, and compared the nucleotide and deduced amino acid sequences with those of the N genes of the lapinized strain of rinderpest virus, measles virus, and canine distemper virus. We have also developed a recombinant baculovirus that expresses the N protein in insect cells and larvae (Spodoptera frugiperda). This protein has been used as a coating antigen for an ELISA that distinguishes vaccinated from rinderpest-infected animals, and has also been used successfully in diagnosing two other morbilliviruses: measles and peste des petits ruminants. The crude lysate of a single infected larva(0.2-0.3g) is sufficient to coat 150 ELISA plates for serological diagnosis of 7200 serum samples in duplicate. Virology 198, 138-147 (1994)

Peste des petits ruminants

Peste des petits ruminants is a viral disease of goats and sheep characterized by erosive stomatitis, enteritis, and pneumonia, with high morbidity and mortality rates that make it a substantial economic burden on developing countries. The causative virus is a member of the family Paramyxoviridae, genus Morbillivirus. We have cloned and sequenced the cDNA of the nucleocapsid (N) gene of the Nigeria 75/1 strain, and compared its nucleotide and deduced amino acid sequence with those of the N gene of a tissue culture-attenuated strain. We have also generated a recombinant baculovirus that expresses the N protein in insect cells and larvae (Spodoptera frugiperda), and characterized the recombinant protein by Western blot analysis. Its authenticity has been shown by its molecular weight of 58 kDa and its recognition by specific antibodies. This recombinant protein has been used successfully as a coating antigen in an ELISA for serological diagnosis of PPRV. Virology 208, 776-778 (1995)

Vesicular Stomatitis

Vesicular stomatitis is a viral disease of cattle, pigs, and horses characterized by vesicular lesions on the teats, feet, and mouth that are virtually indistinguishable from those of foot-and-mouth disease. We have developed a recombinant baculovirus that expresses the nucleocapsid (N) protein of the New Jersey serotype of vesicular stomatitis virus in insect cells (Sf9) and larvae (Spodoptera exigua)to very high levels. This recombinant N protein, expressed in insect cells as a fusion or non-fusion product under the polyhedron promoter, cannot be distinguished by immunological or biochemical analyses from N protein produced by the virus in CHO cells. Lysate of a single infected larva (0.2-0.3g) is adequate for preparing ELISA plates that can perform 10,000 serum assays in duplicate, and the test can also distinguish animals vaccinated with a recombinant glycoprotein from those infected by whole virus or classical vaccines. Virology 192, 207-216 (1993)

Human Immunodeficiency Virus

Human Immunodeficiency Virus In an effort to improve safety of potential AIDS vaccines, we have attenuated vaccinia virus recombinants by co-expressing lymphokines with the immunogen. We have constructed chimeric genes that code for interferons along with structural proteins of the human immunodeficiency virus, type 1; these fusion proteins retain the antigenic characteristics of both interferon and virus as shown by immunoblot analysis. Antiviral activity of interferon could be demonstrated for certain fusion proteins. All recombinants demonstrated attenuating activity of interferon in nude mice, although at varying rates. This activity was not species specific. Implications for the development of attenuated live recombinant vaccines for AIDS are clear. Proc.. Natl. Acad. Sci. USA, Vol 89, pp. 3409-3413, April 1992.

As a safer alternative to inactivated and live-attenuated whole-virus SIV vaccines, we have evaluated the potential for using a surface glycoprotein of a simian immunodeficiency virus(expressed by recombinant vaccinia virus and baculovirus) to immunize and protect rhesus macaques against intravenous infection with pathogenic virus isolates. Although reactive antibodies were induced in all animals following immunization, tests 1 week prior to virus challenge showed they were not neutralizing. All animals became infected after inoculation with 1-10 AID50 of challenge virus. However, immunized macaques challenged with pathogenic simian immunodeficiency virus showed a significantly lower cell-free infectious virus load at 2 weeks postchallenge than unimmunized controls. Virus virulence, immunization regimen, and challenge with homologous or heterologous virus were shown to be critical factors in these results. It is clear that immunization with surface glyprotein may not necessarily provide protective immunity against infection but can reduce virus load. The significance of this effect in delaying onset of disease remains to be determined. AIDS Research and Human Retroviruses, Vol 10, Number 2, 1994