Murine pneumotropic virus VP1 virus-like particles (VLPs) bind to several cell types independent of sialic acid residues and do not serologically cross react with murine polyomavirus VP1 VLPs

Abstract

The ability of murine pneumotropic virus (MPtV) major capsid protein VP1 to form virus-like particles (VLPs) was examined. MPtV-VLPs obtained were used to estimate the potential of MPtV to attach to different cells and to assess some characteristics of the MPtV cell receptor. Furthermore, to evaluate if MPtV-VLPs could potentially complement murine polyomavirus (MPyV) VP1 VLPs (MPyV-VLPs) as vectors for prime-boost gene therapy, the capability of MPtV-VLPs to serologically cross react with MPyV-VLPs and to transduce DNA into cells was examined. MPtV VP1 obtained in a recombinant baculovirus system formed MPtV-VLPs readily. MPtV-VLPs were shown by FACS analysis to bind to different cells, independent of MHC class I antigen expression. In addition, MPtV-VLPs did not cause haemagglutination of red blood cells and MPtV-VLP binding to cells was neuraminidase resistant but mostly trypsin and papain sensitive, indicating that the MPtV receptor lacks sialic acid components. When tested by ELISA and in vivo neutralization assays, MPtV-VLPs did not serologically cross react with MPyV-VLPs, suggesting that MPtV-VLPs and MPyV-VLPs could potentially be interchanged as carriers of DNA in repeated gene therapy. Finally, MPtV-VLPs were shown to transduce foreign DNA in vitro and in vivo.In conclusion, the data suggest that MPtV-VLPs, and possibly also MPtV, bind to several different cell types, that binding is neuraminidase resistant and that MPtV-VLPs should potentially be able to complement MPyV-VLPs for prime-boost gene transfer in vivo.

Intranasal Immunization with Inactivated Influenza Virus Enhances Immune Responses to Coadministered Simian-Human Immunodeficiency Virus-Like Particle Antigens

“…Neither preimmune nor immune sera specific to influenza virus or SHIV VLPs blocked the HI activity of SHIV VLPs (data not shown). We also observed that this HI activity was not diminished by treatment of VLPs with neuraminidase, indicating that the inhibition is not mediated via interaction of neuraminic acid on VLPs with the HA of influenza virus, consistent with a recent study showing that cell binding properties of murine pneumotropic virus VLPs obtained in an rBV system were neuraminidase resistant (45). However, it was found by electron microscopy that inactive influenza virus is able to form aggregates with SHIV VLPs.…”

Minor Capsid Proteins of Simian Virus 40 Are Dispensable for Nucleocapsid Assembly and Cell Entry but Are Required for Nuclear Entry of the Viral Genome

“…The biochemical and cell biological behavior of the Vp3-less Vp1 mutant particles and the Vp1-only particle gives us strong reason to believe that they have structural features similar to those of the SV40 virion. Although we have not characterized these particles structurally by electron microscopy, all previously tested Vp1s from the polyomavirus family, expressed in either bacteria or insect cells (16,22,28,36,45,47,59), have been found to spontaneously form pseudocapsids with sizes (45 to 50 nm in diameter) and shapes similar to those of wild-type virions.…”

A Single Vaccination with Polyomavirus VP1/VP2Her2 Virus-Like Particles Prevents Outgrowth of HER-2/neu–Expressing Tumors

“…VP2PyVLPs and Her2 PyVLPs were produced in Sf9 cells infected with recombinant baculoviruses and purified by a CsCl gradient (12). MPyV-VP1 VLPs were produced as described (12).…”