Source: Office of Scientific Research and Development
Written by: Office of Scientific Research and Development
Edited by: Wang Dongmei

The research group of Prof. Cao Yongchang from the State Key Laboratory of Biocontrol of Sun Yat-sen University, in collaboration with Firstline Biopharmaceuticals Corporation (US), has made a breakthrough in the research of universal influenza vaccines.

Influenza is a zoonosis. In the present, the infection of influenza viruses is still one of the most important causes of human illness and death; for instance, the emergence of influenza H7N9 virus in February of 2013 caused grave losses in the domestic poultry industry and economy of China. Immunization is the major means for influenza prevention. However, influenza viruses infect various hosts and are prone to high mutations; thus the currently used vaccines are only effective against virus strains that are closely related to the vaccine strains. Once a new subtype or a new strain that is a mismatch with the vaccine strains emerges will the current vaccines lose their protective efficacy. Based on the surveillance data of influenza epidemics, WHO annually predicts the epidemic influenza virus strains that might circulate in the next influenza epidemic season, and the predicted strains will be used as the vaccine reference strains. Even though the annual surveillance data are helpful to the selection of the vaccine strains, the prediction cannot be always accurate. When the vaccine strains do not match the epidemic strains, the morbidity and mortality will increase, and when the mismatch is serious, even a pandemic could occur. Therefore, the development of a universal influenza vaccine is urgently needed.

In recent years, the research group of Prof. Cao Yongchang from the State Key Laboratory of Biocontrol of Sun Yat-sen University has collaborated with Firstline Biopharmaceuticals Corporation (US) on the development of universal influenza vaccines. Their studies discovered that, in comparison with the HA proteins from other 17 subtypes of influenza A viruses, the HA protein of H3 subtype (H3 HA) contains a transmembrane domain (TM) with a unique structure that enables H3 HA proteins to form the inter-monomer disulfide bonds so that H3 HA proteins have high stability and heterosubtypic immunity. Furthermore, they replaced H1, H5 and H9 HA TMs with H3 HA TM so that the stability of H1, H5 and H9 HA proteins was increased. Then mice were immunized with modified HAs and subsequently challenged with different subtype viruses. The results demonstrated that the modified H1, H5 and H9 HA proteins with replaced H3 HA TM exhibited enhanced hetero-protection. Encouragingly, 100% protection was achieved with vaccination of modified H5 HA proteins. The results of this study can be seamlessly translated into the current human influenza vaccines, and it can be expected to have a universal influenza vaccine with broad cross-reactive immunity soon.

The results of this research were published online in the journal Vaccine on April 2nd, 2014. Professor Cao is the correspondence author. This research is partially supported by the National Natural Science Foundation and United Fund (U1131005).