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Cross-clade protective immune responses to influenza viruses with H5N1 HA and NA elicited by an influenza virus-like particle.

Bright RA, Carter DM, Crevar CJ, Toapanta FR, Steckbeck JD, Cole KS, Kumar NM, Pushko P, Smith G, Tumpey TM, Ross TM - PLoS ONE (2008)

Bottom Line: However, an apparent association rate of antibody binding to HA correlated with protection and was enhanced using VLPs, particularly when delivered intranasally, compared to rHA vaccines.This is the first report describing the use of an H5N1 VLP vaccine created from a clade 2 isolate.The results show that a non-replicating virus-like particle is effective at eliciting a broadened, cross-clade protective immune response to proteins from emerging H5N1 influenza isolates giving rise to a potential pandemic influenza vaccine candidate for humans that can be stockpiled for use in the event of an outbreak of H5N1 influenza.

View Article: PubMed Central - PubMed

Affiliation: Novavax, Inc., Rockville, Maryland, USA. rbright@novavax.com

ABSTRACT

Background: Vaccination is a cost-effective counter-measure to the threat of seasonal or pandemic outbreaks of influenza. To address the need for improved influenza vaccines and alternatives to egg-based manufacturing, we have engineered an influenza virus-like particle (VLP) as a new generation of non-egg or non-mammalian cell culture-based candidate vaccine.

Methodology/principal findings: We generated from a baculovirus expression system using insect cells, a non-infectious recombinant VLP vaccine from both influenza A H5N1 clade 1 and clade 2 isolates with pandemic potential. VLPs were administered to mice in either a one-dose or two-dose regimen and the immune responses were compared to those induced by recombinant hemagglutinin (rHA). Both humoral and cellular responses were analyzed. Mice vaccinated with VLPs were protected against challenge with lethal reassortant viruses expressing the H5N1 HA and NA, regardless if the H5N1 clade was homologous or heterologous to the vaccine. However, rHA-vaccinated mice showed considerable weight loss and death following challenge with the heterovariant clade virus. Protection against death induced by VLPs was independent of the pre-challenge HAI titer or cell-mediated responses to HA or M1 since vaccinated mice, with low to undetectable cross-clade HAI antibodies or cellular responses to influenza antigens, were still protected from a lethal viral challenge. However, an apparent association rate of antibody binding to HA correlated with protection and was enhanced using VLPs, particularly when delivered intranasally, compared to rHA vaccines.

Conclusion/significance: This is the first report describing the use of an H5N1 VLP vaccine created from a clade 2 isolate. The results show that a non-replicating virus-like particle is effective at eliciting a broadened, cross-clade protective immune response to proteins from emerging H5N1 influenza isolates giving rise to a potential pandemic influenza vaccine candidate for humans that can be stockpiled for use in the event of an outbreak of H5N1 influenza.

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Related in: MedlinePlus

Elicitation of M1 interferon-γ producing splenocytes.ELISPOTs were performed as described in the legend to Fig. 3. Four pools (15mers, overlapping by 11) representing four regions of M1 were used to stimulate cells. HIV-1 Env peptides were used as a non-specific negative control. Splenocytes stimulated with PMA/ionomycin were used as a positive control. Number of IFN-γ ELISPOTs detected using each of the four M1 peptide pools from intramuscularly vaccinated mice with (A) VLP or (B) rHA vaccines.
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pone-0001501-g004: Elicitation of M1 interferon-γ producing splenocytes.ELISPOTs were performed as described in the legend to Fig. 3. Four pools (15mers, overlapping by 11) representing four regions of M1 were used to stimulate cells. HIV-1 Env peptides were used as a non-specific negative control. Splenocytes stimulated with PMA/ionomycin were used as a positive control. Number of IFN-γ ELISPOTs detected using each of the four M1 peptide pools from intramuscularly vaccinated mice with (A) VLP or (B) rHA vaccines.

Mentions: Mice (BALB/c; n = 8) were vaccinated (week 0 and 3) via intramuscular injection or intranasal inoculation with purified influenza VLPs or purified rHA proteins representing the H5N1 isolate A/Viet Nam/1203/2004 (clade 1) or the A/Indonesia/05/2005 (clade 2) isolate. Collected splenocytes and lung cells were stimulated in vitro with pools of peptides specific for influenza H5N1 isolates (Fig. 2). Mice vaccinated with the influenza VLPs had a robust cell-mediated immune response against peptide pools from either the HA (Fig. 3) or M1 (Fig. 4). Cell-mediated immune responses were directed against epitopes in both the HA1 and HA2 subunits in mice vaccinated with VLPs, however, only peptides in pool 2 were recognized from rHA-vaccinated mice (Fig. 3A and B). Splenocytes stimulated with an immunodominant H-2d peptide (HA518) contained in pool 6 had as strong a response as cells stimulated with the entire peptide pool 6. Only VLP-vaccinated mice had cellular responses to M1 (Fig. 4).


Cross-clade protective immune responses to influenza viruses with H5N1 HA and NA elicited by an influenza virus-like particle.

Bright RA, Carter DM, Crevar CJ, Toapanta FR, Steckbeck JD, Cole KS, Kumar NM, Pushko P, Smith G, Tumpey TM, Ross TM - PLoS ONE (2008)

Elicitation of M1 interferon-γ producing splenocytes.ELISPOTs were performed as described in the legend to Fig. 3. Four pools (15mers, overlapping by 11) representing four regions of M1 were used to stimulate cells. HIV-1 Env peptides were used as a non-specific negative control. Splenocytes stimulated with PMA/ionomycin were used as a positive control. Number of IFN-γ ELISPOTs detected using each of the four M1 peptide pools from intramuscularly vaccinated mice with (A) VLP or (B) rHA vaccines.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2200794&req=5

pone-0001501-g004: Elicitation of M1 interferon-γ producing splenocytes.ELISPOTs were performed as described in the legend to Fig. 3. Four pools (15mers, overlapping by 11) representing four regions of M1 were used to stimulate cells. HIV-1 Env peptides were used as a non-specific negative control. Splenocytes stimulated with PMA/ionomycin were used as a positive control. Number of IFN-γ ELISPOTs detected using each of the four M1 peptide pools from intramuscularly vaccinated mice with (A) VLP or (B) rHA vaccines.
Mentions: Mice (BALB/c; n = 8) were vaccinated (week 0 and 3) via intramuscular injection or intranasal inoculation with purified influenza VLPs or purified rHA proteins representing the H5N1 isolate A/Viet Nam/1203/2004 (clade 1) or the A/Indonesia/05/2005 (clade 2) isolate. Collected splenocytes and lung cells were stimulated in vitro with pools of peptides specific for influenza H5N1 isolates (Fig. 2). Mice vaccinated with the influenza VLPs had a robust cell-mediated immune response against peptide pools from either the HA (Fig. 3) or M1 (Fig. 4). Cell-mediated immune responses were directed against epitopes in both the HA1 and HA2 subunits in mice vaccinated with VLPs, however, only peptides in pool 2 were recognized from rHA-vaccinated mice (Fig. 3A and B). Splenocytes stimulated with an immunodominant H-2d peptide (HA518) contained in pool 6 had as strong a response as cells stimulated with the entire peptide pool 6. Only VLP-vaccinated mice had cellular responses to M1 (Fig. 4).

Bottom Line: However, an apparent association rate of antibody binding to HA correlated with protection and was enhanced using VLPs, particularly when delivered intranasally, compared to rHA vaccines.This is the first report describing the use of an H5N1 VLP vaccine created from a clade 2 isolate.The results show that a non-replicating virus-like particle is effective at eliciting a broadened, cross-clade protective immune response to proteins from emerging H5N1 influenza isolates giving rise to a potential pandemic influenza vaccine candidate for humans that can be stockpiled for use in the event of an outbreak of H5N1 influenza.

View Article: PubMed Central - PubMed

Affiliation: Novavax, Inc., Rockville, Maryland, USA. rbright@novavax.com

ABSTRACT

Background: Vaccination is a cost-effective counter-measure to the threat of seasonal or pandemic outbreaks of influenza. To address the need for improved influenza vaccines and alternatives to egg-based manufacturing, we have engineered an influenza virus-like particle (VLP) as a new generation of non-egg or non-mammalian cell culture-based candidate vaccine.

Methodology/principal findings: We generated from a baculovirus expression system using insect cells, a non-infectious recombinant VLP vaccine from both influenza A H5N1 clade 1 and clade 2 isolates with pandemic potential. VLPs were administered to mice in either a one-dose or two-dose regimen and the immune responses were compared to those induced by recombinant hemagglutinin (rHA). Both humoral and cellular responses were analyzed. Mice vaccinated with VLPs were protected against challenge with lethal reassortant viruses expressing the H5N1 HA and NA, regardless if the H5N1 clade was homologous or heterologous to the vaccine. However, rHA-vaccinated mice showed considerable weight loss and death following challenge with the heterovariant clade virus. Protection against death induced by VLPs was independent of the pre-challenge HAI titer or cell-mediated responses to HA or M1 since vaccinated mice, with low to undetectable cross-clade HAI antibodies or cellular responses to influenza antigens, were still protected from a lethal viral challenge. However, an apparent association rate of antibody binding to HA correlated with protection and was enhanced using VLPs, particularly when delivered intranasally, compared to rHA vaccines.

Conclusion/significance: This is the first report describing the use of an H5N1 VLP vaccine created from a clade 2 isolate. The results show that a non-replicating virus-like particle is effective at eliciting a broadened, cross-clade protective immune response to proteins from emerging H5N1 influenza isolates giving rise to a potential pandemic influenza vaccine candidate for humans that can be stockpiled for use in the event of an outbreak of H5N1 influenza.

Show MeSH
Related in: MedlinePlus