Reverse genetics based rgH5N2 vaccine provides protection against high dose challenge of H5N1 avian influenza virus in chicken

• Published in: Microbial pathogenesis Vol. 97; pp. 172 - 177
• Main Authors: Bhatia, S., Khandia, R., Sood, R., Bhat, S., Siddiqui, A., Jahagirdhar, G., Mishra, S., Mishra, A., Pateriya, A.K., Kulkarni, D.D.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.08.2016
• Subjects: Animals; Avian influenza; Chickens; Cloaca - virology; H5N1; Influenza A Virus, H1N1 Subtype - genetics; Influenza A Virus, H1N1 Subtype - immunology; Influenza A Virus, H5N1 Subtype - immunology; Influenza A Virus, H5N2 Subtype - genetics; Influenza A Virus, H5N2 Subtype - immunology; Influenza A Virus, H9N2 Subtype - genetics; Influenza A Virus, H9N2 Subtype - immunology; Influenza in Birds - prevention & control; Influenza in Birds - virology; Influenza Vaccines - administration & dosage; Influenza Vaccines - genetics; Influenza Vaccines - immunology; Oropharynx - virology; Orthomyxoviridae; Real-Time Polymerase Chain Reaction; Reverse Genetics; Treatment Outcome; Vaccine; Vaccines, Inactivated - administration & dosage; Vaccines, Inactivated - genetics; Vaccines, Inactivated - immunology; Vaccines, Synthetic - administration & dosage; Vaccines, Synthetic - genetics; Vaccines, Synthetic - immunology; Virus Shedding; Avian influenza; H5N1; Vaccine; Reverse genetics
• ISSN: 0882-4010; 1096-1208
• DOI: 10.1016/j.micpath.2016.06.011

An inactivated vaccine was developed using the rgH5N2 virus (6 + 2 reassortant) generated by plasmid based reverse genetics system (RGS) with WSN/33/H1N1 as backbone virus. Following mutation of the basic amino acid cleavage site RRRKKR*GLF to IETR*GLF, the H5-HA (haemagglutinin) gene of the selected donor H5N1 virus (A/chicken/West Bengal/80995/2008) of antigenic clade 2.2 was used along with the N2-NA gene from H9N2 field isolate (A/chicken/Uttar Pradesh/2543/2004) for generation of the rgH5N2 virus. A single dose (0.5 ml/bird) of the inactivated rgH5N2 vaccine protected 100% of the vaccinated chickens (n = 10) on 28th dpv (early challenge) and 90% of the vaccinated chickens (n = 10) on 200th dpv (late challenge) against high dose challenge with HPAI virus (109 EID50/bird). Challenge virus shedding via oropharynx and cloaca of the vaccinated chickens was detectable by realtime RT-PCR during 1–5 dpc and 1–9 days dpc in the early and the late challenge, respectively. The protective level of antibodies (mean HI titre > 128) was maintained without booster vaccination for 200 days. The present study provides the experimental evidence about the extent of protection provided by a reverse genetics based vaccine for clade 2.2 H5N1 viruses against challenge with high dose of field virus at two different time points (28 dpv and 200 dpv). The challenge study is uniquely different from the previous similar experiments on account of 1000 times higher dose of challenge and protection at 200 dpv. The protection and virus shedding data of the study may be useful for countries planning to use H5 vaccine in poultry especially against the clade 2.2 H5N1 viruses. •An inactivated rgH5N2 (clade 2.2) vaccine was developed by reverse genetics.•The vaccinated chickens were protected against high dose challenge of H5N1 virus.•Virus shedding in the vaccinated birds was detected during 1–5 days post challenge.•A mean HI titre of >128 was maintained without booster vaccination for 200 days.•90% of vaccinated chickens were protected from challenge at 6 month post vaccination.