Pseudotyped Single-Cycle Simian Immunodeficiency Viruses Expressing Gamma Interferon Augment T-Cell Priming Responses In Vitro

Abstract

To increase the safety and efficacy of human immunodeficiency virus vaccines, several groups have conducted studies using the macaque model with single-cycle replicating simian immunodeficiency viruses (SIVs). However, these constructs had poor or diminished efficacy compared to live attenuated vaccines. We previously showed that immunization of macaques with live attenuated SIV with a deletion in the nef gene and expressing gamma interferon (

Incorporation of CD40 Ligand into the Envelope of Pseudotyped Single-Cycle Simian Immunodeficiency Viruses Enhances Immunogenicity

“…In the SIV/macaque model and in HIV-infected humans, a Th1 response correlates with control of virus replication (74). Thus, we developed single-cycle, VSV-G-pseudotyped SIV viral particles expressing IFN-␥ and showed that transduction with these constructs increased DC maturation and their ability to activate CD4 ϩ and CD8 ϩ lymphocytes (55). In the present study, we incorporated CD40L, one of the most potent stimuli for DCs, into the membrane of Transduction with CD40L-dSIVs resulted in activated DCs and significantly increased levels of CD54, CD80, CD86, and HLA-DR expression compared to results for the PBS and dSIV-transduced groups.…”

“…Previously we demonstrated that expression of IFN-␥, a Th1 cytokine, in vaccinia virus and SIV vectors increases attenuation as well as enhancing host immune responses (24,25,39,55). The adaptive immune response is initiated when naive T cells interact with DCs, dictating the development of a Th1 or Th2 immune response (34).…”

“…dSIVs were prepared as follows: 293T cells (90% confluent in 150-cm 2 flasks) were cotransfected with pSIV⌬E⌬Ngfp (36 g) and pVSV-G (18 g; Clontech, California). pSIV⌬E⌬Ngfp contains the SIVmac239 genome with a partial deletion of the env gene and with the nef gene replaced with the green fluorescent protein (GFP) gene (55) (Fig. 1A).…”

“…Several groups have constructed replication-defective SIVs whose infection is limited to a single round of replication to reduce the risk of reversion to virulence while simultaneously maintaining efficacy similar to that of live attenuated vaccines (17,36). Our laboratory and others have constructed vesicular stomatitis virus glycoprotein (VSV-G)-pseudotyped SIVs (dSIV) (55,64). Pseudotyping with VSV-G expands tissue tropism, potentially enhances immune responses, and stabilizes the viral structure, allowing ultracentrifugation and ultrafiltration without losing infectivity (10).…”

Lower Levels of Gamma Interferon Expressed by a Pseudotyped Single-Cycle Simian Immunodeficiency Virus Enhance Immunogenicity in Rats

“…We previously constructed vesicular stomatitis virus glycoprotein (VSV-G)-pseudotyped single-cycle simian immunodeficiency viruses (SIVs) expressing two different levels of gamma interferon (IFN-␥), and we showed that IFN-␥ acts as an adjuvant to augment T-cell priming by antigen-presenting cells in an in vitro model (35). We have now proceeded to an in vivo model to further assess the levels of immunogenicity and efficacy of these constructs.…”