Enhanced protective efficacy of H5 subtype avian influenza DNA vaccine with codon optimized HA gene in a pCAGGS plasmid vector.
ABSTRACT H5N1 influenza viruses have caused significant disease and deaths in various parts of the world in several species, including humans. Vaccination combined with culling can provide an attractive method for outbreak containment. Using synthesized oligos and overlapping extension PCR techniques, we constructed an H5 HA gene, optiHA, containing chicken biased codons based on the HA amino acid sequence of the highly pathogenic H5N1 virus A/goose/Guangdong/1/96 (GS/GD/96). The optiHA and wild-type HA genes were inserted into plasmids pCI or pCAGGS, and designated as pCIoptiHA, pCAGGoptiHA, pCIHA and pCAGGHA, respectively. To evaluate vaccine efficacy, groups of 3-week-old specific pathogen free (SPF) chickens were intramuscularly injected with the four plasmids. Sera were collected on a weekly basis post-vaccination (p.v.) for hemagglutination inhibition (HI) assays and neutralization (NT) antibody detection. All chickens receiving pCAGGoptiHA and pCAGGHA developed high levels of HI and NT antibodies at 3 weeks p.v., and were completely protected from lethal H5 virus challenge, while only partial protection was induced by inoculation with the other two plasmids. A second experiment was conducted to evaluate if a lower dose of the pCAGGoptiHA vaccine could be effective, results indicated that two doses of 10 microg of pCAGGoptiHA could induce complete protection in chickens against H5 lethal virus challenge. Based on our results, we conclude that construction optimization could dramatically increase the H5 HA gene DNA vaccine efficacy in chickens, and therefore, greatly decrease the dose necessary for inducing complete protection in chickens.
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ABSTRACT: Highly pathogenic H5N1 avian influenza virus was first detected in the People's Republic of China (China) in 1996 and has caused over 100 outbreaks of disease in poultry since 2004. The Chinese Government has pursued a vaccination strategy to control avian influenza infection in poultry. A series of vaccines including whole-virus inactivated vaccine, recombinant fowlpox vaccine and recombinant Newcastle disease virus vaccine have been developed and billions of doses of the vaccines are produced every year. The Government has also developed strategies to fund vaccine production and to offer financial compensation for the slaughter of infected poultry. The vaccination strategy has been effective and has played an important role in reducing the incidence of H5N1 infection in poultry and in markedly reducing the number of cases of human infection. Despite the successes obtained with the vaccination strategy, China still faces challenges in its efforts to eliminate H5N1 virus circulation in poultry.Revue scientifique et technique (International Office of Epizootics) 05/2009; 28(1):267-74. · 0.69 Impact Factor
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ABSTRACT: Following the first detection of the highly pathogenic H5N1 avian influenza virus in sick geese in Guangdong Province in China in 1996, scientists began to develop vaccines in preparation for an avian influenza pandemic. An inactivated H5N2 vaccine was produced from a low pathogenic virus, A/turkey/England/N-28/73, and was used for buffer zone vaccination during H5N1 outbreaks in 2004 in China. We also generated a low pathogenic H5N1 reassortant virus (Re-1) that derives its HA and NA genes from the GS/GD/96 virus and six internal genes from the high-growth A/Puerto Rico/8/34 (PR8) virus using plasmid-based reverse genetics. The inactivated vaccine derived from the Re-1 strain could induce more than ten months of protective immunity in chickens after one-dose inoculation; most importantly, this vaccine is immunogenic for geese and ducks. We recently developed a Newcastle virus-vectored live vaccine that exhibits great promise for use in the field to prevent highly pathogenic avian influenza and Newcastle disease in chickens. Over 30 billion doses of these vaccines have been used in China and other countries, including Vietnam, Mongolia, and Egypt, and have played an important role in H5N1 avian influenza control in these countries.Current topics in microbiology and immunology 01/2009; 333:153-62. · 4.86 Impact Factor
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ABSTRACT: H5 low pathogenic avian influenza virus (LPAIV) infection in domestic ducks is a major problem in duck producing countries. Their silent circulation is an ongoing source of potential highly pathogenic or zoonotic emerging strains. To prevent such events, vaccination of domestic ducks might be attempted but remains challenging. Currently licensed vector vaccines derived from H5N1 HPAIV possess clade 0, clade 2.2 or clade 2.3.4 HA sequences: selection of the best HA candidate inducing the largest cross protection is a key issue. For this purpose, DNA immunization of specific pathogen free Muscovy ducks was performed using different synthetic codon optimized (opt) or native HA genes from H5N2 LPAIV and several H5N1 HPAIV clade 2.1, 2.2.1 and 2.3.4. Humoral cross-immunity was assessed 3 weeks after boost by hemagglutination inhibition (HI) and virus neutralization (VN) against three French H5 LPAIV antigens. Vaccination with LP H5N2 HA induced the highest VN antibody titre against the homologous antigen; however, the corresponding HI titre was lower and comparable to HI titres obtained after immunization with opt HA derived from clades 2.3.4 or 2.1. Compared to the other HPAIV-derived constructs, vaccination with clade 2.3.4 opt HA consistently induced the highest antibody titres in HI and VN, when tested against all three H5 LPAIV antigens and H5N2 LPAIV, respectively: differences in titres against this last strain were statistically significant. The present study provides a standardized method to assess cross-immunity based on HA immunogenicity alone, and suggests that clade 2.3.4-derived recombinant vaccines might be the optimal candidates for further challenge testing to vaccinate domestic Muscovy ducks against H5 LPAIV.Virology Journal 04/2014; 11(1):74. · 2.09 Impact Factor