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1 Inactivated Retroviruses That Retain Functional and Structural Envelope Proteins: Use as Vaccines and in Vitro Reagents
L. O. Arthur*1, R. Benveniste2, R. Desrosiers3, J. Hoxie4, E. N. Chertova1, J. W. Bess1, L. E. Henderson1, and J. D. Lifson1
1AVP, SAIC Frederick, NCI-FCRDC, Frederick, MD, USA; 2NCI, LGD, Frederick, MD, USA; 3Harvard Med. Sch., NERPRC, Southborough, MA, USA; 4Univ. of Pennsylvania, Philadelphia, USA
The availability of viral envelope protein in its native structure is important in studying virus-cell interactions, in assessing immunological responses in lentivirus infection and vaccination, and as an immunogen in vaccine development. We have developed an inactivation procedure: utilizing mild oxidizing reagents (i.e., Aldrithiol-2) to inactivate virions yet retain the conformational and functional integrity of the proteins on the virion surface. Viral infectivity inactivation has been demonstrated by tissue culture analysis and in vivo by inoculation of macaques. Six macaques each were inoculated with 10 mg of purified SIVMne (equivalent to 3.3 ( 108 infectious virus) or SIVMac 239 and with no detection of infectious virus. Macaques immunized with inactivated SIVMne E11S were protected from challenge with the homologous, pathogenic SIVMne propagated in M. nemestrina cells but were not protected from a heterologous challenge, SIV E660. Since inactivated viruses can be used as a platform for testing molecularly altered gp120 in vaccine studies, we have a number of experiments in progress to assess molecularly modified gp120 in induction of neutralizing antibodies, in stimulation of T-cell responses, and in protection of primates from challenge. These include the assessment of partially deglycosylated gp120 and modifications that enrich gp120 on virus by approximately 10-fold. Additional viruses with modified gp120 have been produced and inactivated and will be tested. These include viruses with deleted V1 and V2 loops, gp120 modifications to yield CD4-independent infection, and primary HIV-1 isolates. In addition, these inactivated viruses with structurally and functionally intact gp120 have proven to be valuable in vitro reagents for assessing immune responses. These particles have been used as antigens in lymphocyte proliferation assays and cellular cytokine secretion assays (ELISPOT).
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