Zhao Bingbing, Wang Wenqing, Song Yating, Wen Xiangyang, Feng Siyu, Li Weiqiang, Ding Yangbao, Chen Zuxian, He Zhuoliang, Wang Shao, Jiao Peirong
Guangdong Laboratory for Lingnan Modern Agriculture, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China.
Guangdong Provincial Key Laboratory of Zoonosis Prevention and Control, Guangzhou, China.
Front Microbiol. 2023 Mar 7;14:1105529. doi: 10.3389/fmicb.2023.1105529. eCollection 2023.
Since 2017, the new H7N9 highly pathogenic avian influenza viruses (HPAIVs) have been responsible for more than 200,000 cases of chicken infection and more than 120,000 chicken deaths in China. Our previous study found that the Q26 was chicken-origin H7N9 HPAIV. In this study, we analyzed the genetic characterization of Q24, Q65, Q66, Q85, and Q102 H7N9 avian influenza viruses isolated from Guangdong, China in 2017. Our results showed that these viruses were highly pathogenic and belonged to two different genotypes, which suggested they occurred genetic reassortant. To investigate the pathogenicity, transmission, and host immune responses of H7N9 virus in chickens, we selected Q24 and Q26 viruses to inoculate chickens. The Q24 and Q26 viruses killed all inoculated chickens within 3 days and replicated effectively in all tested tissues. They were efficiently transmitted to contact chickens and killed them within 4 days through direct contact. Furthermore, we found that the expressions of several immune-related genes (e.g., TLR3, TLR7, MDA5, MAVS, IFN-β, IL-6, IL-8, OAS, Mx1, MHC I, and MHC II) were upregulated obviously in the lungs and spleen of chickens inoculated with the two H7N9 viruses at 24 h post-inoculation (HPI). Among these, IL-6 and IFN-β in lungs were the most upregulated (by 341.02-381.48-fold and 472.50-500.56-fold, respectively). These results suggest that the new H7N9 viruses isolated in 2017, can replicate and transmit effectively and trigger strong immune responses in chickens, which helps us understand the genetic and pathogenic variations of H7N9 HPAIVs in China.
自2017年以来，新型H7N9高致病性禽流感病毒（HPAIVs）已在中国导致超过20万例鸡感染病例和超过12万只鸡死亡。我们之前的研究发现Q26是鸡源H7N9 HPAIV。在本研究中，我们分析了2017年从中国广东分离的Q24、Q65、Q66、Q85和Q102 H7N9禽流感病毒的基因特征。我们的结果表明，这些病毒具有高致病性，属于两种不同的基因型，这表明它们发生了基因重配。为了研究H7N9病毒在鸡中的致病性、传播及宿主免疫反应，我们选择Q24和Q26病毒接种鸡。Q24和Q26病毒在3天内杀死了所有接种的鸡，并在所有测试组织中有效复制。它们通过直接接触有效地传播给接触鸡，并在4天内将其杀死。此外，我们发现接种两种H7N9病毒的鸡在接种后24小时（HPI）时，肺和脾中几个免疫相关基因（如TLR3、TLR7、MDA5、MAVS、IFN-β、IL-6、IL-8、OAS、Mx1、MHC I和MHC II）的表达明显上调。其中，肺中的IL-6和IFN-β上调最为明显（分别上调341.02 - 381.48倍和472.50 - 500.56倍）。这些结果表明，2017年分离的新型H7N9病毒能够在鸡中有效复制和传播，并引发强烈的免疫反应，这有助于我们了解中国H7N9 HPAIVs的基因和致病性变异。
