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Volume 19, Number 12—December 2013

Dispatch

Novel Variants of Clade 2.3.4 Highly Pathogenic Avian Influenza A(H5N1) Viruses, China

Min Gu, Guo Zhao, Kunkun Zhao, Lei Zhong, Junqing Huang, Hongquan Wan, Xiaoquan Wang, Wenbo Liu, Huimou Liu, Daxin Peng, and Xiufan LiuComments to Author 
Author affiliations: College of Veterinary Medicine, Yangzhou University, Yangzhou, China (M. Gu, G. Zhao, K. Zhao, L. Zhong, J. Huang, H. Wan, X. Wang, W. Liu, H. Liu, D. Peng, X. Liu); Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou (M. Gu, X. Wang, W. Liu, H. Liu, D. Peng, X. Liu)

Main Article

Table 2

Efficacy of vaccines against highly pathogenic avian influenza virus A(H5N1) clade 2.3.4 variants in chickens, China*

Virus and vaccine type HI titer ±SD, log2
Challenge test results, by swab type, no. positive birds/no. tested (mean titer ±SD)†
No. surviving birds/total no.
3 dpc
5 dpc
Re-4 Re-5 k0602 Tracheal Cloacal Tracheal Cloacal
k0602
Re-4/Re-5 8.10 ±0.97 6.20 ±0.31 2.25 ±0.45 6/6 (3.79 ±1.46) 4/6 (2.25 ±2.39) 2/3 (2.17 ±2.40) 2/3 (2.92 ±2.55) 1/7
rk0602 2.10 ±0.37 3.27 ±0.33 9.35 ±0.75 0/10 0/10 0/10 0/10 10/10
Control‡
ND
ND
ND

ND
ND

ND
ND
0/5
k0603
Re-4/Re-5 7.70 ±0.26 5.70 ±0.29 1.93 ±1.21 8/8 (3.15 ±1.30) 8/8 (3.50 ±0.25) 3/3 (3.50 ±0.43) 3/3 (2.33 ±0.58) 1/10
rk0602 2.05 ±0.85 2.75 ±0.57 9.25 ±0.71 0/10 0/10 0/10 0/10 10/10
Control‡ ND ND ND ND ND ND ND 0/5

*Chickens were immunized with the Re4/Re5 or the inactivated rk0602 vaccine (the HA and NA genes of rk0602 were derived from subtype H5N1 k0602 virus; the internal genes were from PR8), and HI antibody titers were determined on day 28 postvaccination. HI, hemagglutination inhibition assay; dpc, days postchallenge; ND, not done.
†Birds were challenged with 106.0 50% egg infectious dose (EID50) of k0602 or k0603 virus; virus titers are expressed as log10 EID50/0.1 mL.
‡Two groups of 5 mock-vaccinated chickens served as controls; all died within 3 dpc.

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