Pathogenicity, Transmission and Antigenic Variation of H5N1 Highly Pathogenic Avian Influenza Viruses

Peirong Jiao; Hui Song; Xiaoke Liu; Yafen Song; Jin Cui; Siyu Wu; Jiaqi Ye; Nanan Qu; Tiemin Zhang; Ming Liao

doi:10.3389/fmicb.2016.00635

Pathogenicity, Transmission and Antigenic Variation of H5N1 Highly Pathogenic Avian Influenza Viruses

Front Microbiol. 2016 May 6:7:635. doi: 10.3389/fmicb.2016.00635. eCollection 2016.

Authors

Peirong Jiao¹, Hui Song¹, Xiaoke Liu², Yafen Song¹, Jin Cui³, Siyu Wu¹, Jiaqi Ye¹, Nanan Qu¹, Tiemin Zhang⁴, Ming Liao¹

Affiliations

¹ National and Regional Joint Engineering Laboratory for Medicament of Zoonosis Prevention and ControlGuangzhou, China; Key Laboratory of Animal Vaccine Development, Ministry of AgricultureGuangzhou, China; Key Laboratory of Zoonosis Prevention and Control of GuangdongGuangzhou, China; College of Veterinary Medicine, South China Agricultural UniversityGuangzhou, China.
² National and Regional Joint Engineering Laboratory for Medicament of Zoonosis Prevention and ControlGuangzhou, China; Pulike Biological Engineering Inc.Luoyang, China.
³ Key Laboratory of Animal Vaccine Development, Ministry of AgricultureGuangzhou, China; Key Laboratory of Zoonosis Prevention and Control of GuangdongGuangzhou, China; College of Veterinary Medicine, South China Agricultural UniversityGuangzhou, China.
⁴ College of Engineering, South China Agricultural University Guangzhou, China.

Abstract

H5N1 highly pathogenic avian influenza (HPAI) was one of the most important avian diseases in poultry production of China, especially in Guangdong province. In recent years, new H5N1 highly pathogenic avian influenza viruses (HPAIV) still emerged constantly, although all poultry in China were immunized with H5N1 vaccinations compulsorily. To better understand the pathogenicity and transmission of dominant clades of the H5N1 HPAIVs in chicken from Guangdong in 2012, we chose a clade 7.2 avian influenza virus named A/Chicken/China/G2/2012(H5N1) (G2) and a clade 2.3.2.1 avian influenza virus named A/Duck/China/G3/2012(H5N1) (G3) in our study. Our results showed that the chickens inoculated with 10(3) EID50 of G2 or G3 viruses all died, and the titers of virus replication detected in several visceral organs were high but different. In the naive contact groups, virus shedding was not detected in G2 group and all chickens survived, but virus shedding was detected in G3 group and all chickens died. These results showed that the two clades of H5N1 HPAIVs had high pathogenicity in chickens and the contact transmission of them was different in chickens. The results of cross reactive HI assay showed that antigens of G2 and G3 were very different from those of current commercial vaccines isolates (Re-4, Re-6, and D7). And to evaluate the protective efficacy of three vaccines against most isolates form Guangdong belonging to clade 2.3.2.1 in 2012, G3 was chosen to challenge the three vaccines such as Re-4, Re-6, and D7. First, chickens were immunized with 0.3 ml Re-4, Re-6, and D7 inactivated vaccines by intramuscular injection, respectively, and then challenged with 10(6) EID50 of G3 on day 28 post-vaccination. The D7 vaccine had 100% protection against G3 for chickens, the Re-6 vaccine had 88.9%, and the Re-4 vaccine only had 66.7%. Our results suggested that the D7 vaccine could prevent and control H5N1 virus outbreaks more effectively in Guangdong. From the above, it was necessary to conduct continuously epidemiological survey and study the pathogenicity and antigenic variation of avian influenza in Southern China.

Keywords: H5N1; antigenic variation; pathogenicity; transmissibility; vaccine.