Construction and Testing of orfA +/- FIV Reporter Viruses

Hind J Fadel,Dyana T Saenz,Eric M Poeschla

doi:10.3390/v4010184

Abstract

Single cycle reporter viruses that preserve the majority of the HIV-1 genome, long terminal repeat-promoted transcription and Rev-dependent structural protein expression are useful for investigating the viral life cycle. Reporter viruses that encode the viral proteins in cis in this way have been lacking for feline immunodeficiency virus (FIV), where the field has used genetically minimized transfer vectors with viral proteins supplied in trans. Here we report construction and use of a panel of single cycle FIV reporter viruses that express fluorescent protein markers. The viruses can be produced to high titer using human cell transfection and can transduce diverse target cells. To illustrate utility, we tested versions that are (+) and (-) for OrfA, an FIV accessory protein required for replication in primary lymphocytes and previously implicated in down-regulation of the primary FIV entry receptor CD134. We observed CD134 down-regulation after infection with or without OrfA, and equivalent virion production as well. These results suggest a role for FIV proteins besides Env or OrfA in CD134 down-regulation.

Highlights

Initial analyses of a retrovirus typically involve monitoring productive replication of clinical isolates or passaged viral strains
We describe a set of four feline immunodeficiency virus (FIV) reporter viruses in which fluorescent proteins are expressed as
Alternative marker gene arrangements may be feasible for FIV but the present insertion into env preserved viral production and infectivity. These reporter viruses add to the experimental armamentarium by allowing the FIV life cycle to be assessed in the same manner as HIV-1 has been assessed for years [2,3,25]

Summary

Introduction

Initial analyses of a retrovirus typically involve monitoring productive replication of clinical isolates or passaged viral strains. For basic virology in which the goal is to analyze the life cycle with fidelity to the natural situation, it is often more desirable to use an HIV-1 reporter virus that has been rendered minimally replication-defective with a frame-shift or deletion in env. This is advantageous if the complex transcription, genomic RNA splicing and protein expression cascade that eventuates in Rev-dependent protein accumulation is under study. Non-primate lentiviruses such as FIV, EIAV and Visna provide informative comparative models, and in the case of FIV, AIDS can be studied For these lentiviruses, minimal vector systems have been engineered [5]. We describe the construction and initial use of FIV reporter viruses

Results

Background

Experimental Section

Discussion and Conclusions