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Soluble recombinant human metapneumovirus G protein is immunogenic but not protective.

ABSTRACT: Human metapneumovirus (HMPV) expresses the major surface glycoproteins F and G. We evaluated the protective efficacy of immunization with G. We generated a recombinant form of G ectodomain (GDeltaTM) that was secreted from mammalian cells and purified by affinity chromatography. We tested the immunogenicity of GDeltaTM in cotton rats. Animals were immunized with PBS, GDeltaTM alone or adjuvanted, or were infected once with HMPV, and challenged with live HMPV at 28 days. Animals vaccinated with adjuvanted and non-adjuvanted GDeltaTM developed high levels of serum antibodies to both recombinant and native G protein; however, vaccinated animals did not develop neutralizing antibodies and were not protected against virus challenge. Unlike the analogous non-fusion glycoproteins of other human paramyxoviruses, HMPV G does not appear to be a protective antigen. This represents an unusual feature of HMPV.

SUBMITTER: Ryder AB

PROVIDER: S-EPMC2894472 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

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Soluble recombinant human metapneumovirus G protein is immunogenic but not protective.

Ryder Alex B AB Tollefson Sharon J SJ Podsiad Amy B AB Johnson Joyce E JE Williams John V JV

Vaccine 20100422 25

Human metapneumovirus (HMPV) expresses the major surface glycoproteins F and G. We evaluated the protective efficacy of immunization with G. We generated a recombinant form of G ectodomain (GDeltaTM) that was secreted from mammalian cells and purified by affinity chromatography. We tested the immunogenicity of GDeltaTM in cotton rats. Animals were immunized with PBS, GDeltaTM alone or adjuvanted, or were infected once with HMPV, and challenged with live HMPV at 28 days. Animals vaccinated with a ...[more]

PMID: 20417260

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Project description:A chimeric yellow fever (YF)-dengue type 2 (dengue-2) virus (ChimeriVax-D2) was constructed using a recombinant cDNA infectious clone of a YF vaccine strain (YF 17D) as a backbone into which we inserted the premembrane (prM) and envelope (E) genes of dengue-2 virus (strain PUO-218 from a case of dengue fever in Bangkok, Thailand). The chimeric virus was recovered from the supernatant of Vero cells transfected with RNA transcripts and amplified once in these cells to yield a titer of 6.3 log(10) PFU/ml. The ChimeriVax-D2 was not neurovirulent for 4-week-old outbred mice inoculated intracerebrally. This virus was evaluated in rhesus monkeys for its safety (induction of viremia) and protective efficacy (induction of anti-dengue-2 neutralizing antibodies and protection against challenge). In one experiment, groups of non-YF-immune monkeys received graded doses of ChimeriVax-D2; a control group received only the vaccine diluents. All monkeys (except the control group) developed a brief viremia and showed no signs of illness. Sixty-two days postimmunization, animals were challenged with 5.0 log(10) focus forming units (FFU) of a wild-type dengue-2 virus. No viremia (<1.7 log(10) FFU/ml) was detected in any vaccinated group, whereas all animals in the placebo control group developed viremia. All vaccinated monkeys developed neutralizing antibodies in a dose-dependent response. In another experiment, viremia and production of neutralizing antibodies were determined in YF-immune monkeys that received either ChimeriVax-D2 or a wild-type dengue-2 virus. Low viremia was detected in ChimeriVax-D2-inoculated monkeys, whereas all dengue-2-immunized animals became viremic. All of these animals were protected against challenge with a wild-type dengue-2 virus, whereas all YF-immune monkeys and nonimmune controls became viremic upon challenge. Genetic stability of ChimeriVax-D2 was assessed by continuous in vitro passage in VeroPM cells. The titer of ChimeriVax-D2, the attenuated phenotype for 4-week-old mice, and the sequence of the inserted prME genes were unchanged after 18 passages in Vero cells. The high replication efficiency, attenuation phenotype in mice and monkeys, immunogenicity and protective efficacy, and genomic stability of ChimeriVax-D2 justify it as a novel vaccine candidate to be evaluated in humans.

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Soluble recombinant human metapneumovirus G protein is immunogenic but not protective.

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Soluble recombinant human metapneumovirus G protein is immunogenic but not protective.

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