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Protective Immunity Against Influenza H5N1 Virus Challenge in Chickens by Recombinant Lactococcus

27 April 2015

Researchers from Nanchang in China have found a novel oral vaccine to be effective against the H5N1 highly pathogenic avian influenza virus in chickens.

Highly pathogenic H5N1 avian influenza viruses pose a debilitating pandemic threat in poultry, according to Han Lei and colleagues at Nanchang University in China.

In their paper, published in BMC Veterinary Research, they explain that current influenza vaccines predominantly focus on haemagglutinin (HA) which anti-HA antibodies are often neutralising, and are used routinely to assess vaccine immunogenicity.

However, they continue, neuraminidase (NA), the other major glycoprotein on the surface of the influenza virus, has historically served as the target for antiviral drug therapy and is much less studied in the context of humoral immunity.

The aim of their study was to evaluate the protective immunity of NA based on Lactococcus lactis (L.lactis) expression system against homologous H5N1 virus challenge in a chicken model.

L.lactis/pNZ2103-NA which NA is derived from A/Vietnam/1203/2004 (H5N1) (VN/1203/04) was constructed based on L.lactis constitutive expression system in this study.

Chickens vaccinated orally with 1012 colony-forming unit (CFU) of L.lactis/pNZ2103-NA could elicit significant NA-specific serum IgG and mucosa IgA antibodies, as well as neuraminidase inhibition (NI) titre compared with chickens administered orally with saline or L.lactis/pNZ2103 control.

Most importantly, the results revealed that chickens administered orally with L.lactis/pNZ2103-NA were completely protected from a lethal H5N1 virus challenge.

The data obtained in the present study indicate that recombinant L.lactis/pNZ2103-NA in the absence of adjuvant can be considered an effective mucosal vaccine against H5N1 infection in chickens via oral administration, concluded Lei and colleagues.

They added that their findings support the use of recombinant L.lactis/pNZ2103-NA to perform mass vaccination in poultry during A/H5N1 pandemic.


Lei H., X. Peng, J. Ouyang, D. Zhao, H. Jiao, H. Shu and X. Ge. 2015. Protective immunity against influenza H5N1 virus challenge in chickens by oral administration of recombinant Lactococcus lactis expressing neuraminidase. BMC Veterinary Research 2015, 11:85 doi:10.1186/s12917-015-0399-4

Further Reading

You can view the full report by clicking here.
You can visit the Avian Flu page by clicking here.

April 2015

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