Paul A. Luciw

Antigenicity and immunogenicity of domains of the human immunodeficiency virus (HIV) envelope polypeptide expressed in the yeast Saccharomyces cerevisiae.

Expression vectors were constructed for the production of various domains of the envelope gene product of the SF-2 isolate of human immunodeficiency virus (HIV) in the yeast Saccharomyces cerevisiae. Serum specimens from HIV seropositive blood donors reacted in immunoblot assays with recombinant polypeptides from both the gp120 and gp41 coding regions of env. Polypeptides from both domains were purified and injected into experimental animals. Antibodies raised in rabbits to env-2, a recombinant polypeptide representing the majority of the protein moiety of gp120, reacted with fully glycosylated native gp120 of HIV-SF2 virions. In addition, these env-2 antisera showed reactivity with viral gp120 of divergent HIV isolates. A 121 amino acid polypeptide (env-5), representing the region of gp41 stretching between the two hydrophobic domains of the protein, elicited antibodies in rabbits that reacted with glycosylated, native gp41. Thus, selected domains of the HIV env gene expressed in genetically engineered yeast, are recognized by sera from HIV infected humans, elicit antibodies that react with native HIV glycoproteins and provide a source of envelope antigens for evaluation as potential subunit vaccines for HIV.

Recombinant DNA approaches to feline leukemia virus immunization.

We have utilized 2 recombinant DNA strategies for immunization against FeLV in cats: (a) modified live virus was attenuated by mutation and recombination, and (b) an immunogen, consisting of subunit envelope protein, was prepared in genetically engineered yeast. Results indicated that the genetically manipulated live virus preparations were not protective against FeLV challenge because they were either not attenuated in virulence or were not sufficiently antigenic. Immunization with yeast-synthesized FeLV envelope protein followed by the modified live virus gave protective immunity in cats under experimental conditions. Future immunization attempts will concentrate on enhancing the immunogenic potency of the yeast- synthesized FeLV envelope protein.