新型H3N3亚型禽流感病毒对鸡致病性与传播性研究

新型禽流感病毒对家禽养殖业可造成严重经济损失，及时发现和阻断其传播具有重要意义。2022—2023年，本实验室在我国发病鸡群中监测到新型H3N3亚型禽流感病毒的出现和传播。本研究对发病鸡群开展了临床发病情况调查，对分离病毒进行了全基因组演化分析，并对分离的代表性病毒进行了鸡致病性以及空气传播性试验。结果表明：1)H3N3最早于2022年12月在华东地区发生产蛋下降的蛋鸡群出现，随后陆续在华东、华北、东北等多个地区的鸡群中监测到，发病群体主要为产蛋鸡，鸡群发病率高，死亡率低(1%～5%),主要引起产蛋率急性下降(10%～40%)。2)病毒全基因组序列分析显示，H3N3病毒为新型重排病毒，由鸡群中流行的H3N8病毒与H10N3病毒重排产生，6个内部基因来源于H9N2病毒。3)与H3N8病毒类似，新型H3N3病毒对鸡群高度易感，可在鸡鼻甲、气管、肺等呼吸器官中高效复制并排毒，引起呼吸系统严重病理损伤。4)空气传播性结果表明，新型H3N3病毒可在鸡群之间空气传播，而H3N8病毒不能在鸡群间空气传播。综上，新型H3N3禽流感病毒对鸡具有较强的致病性和传播性，有可能成为新的优势流行病毒，对我国家禽...

Pathogenicity and airborne transmissibility of novel reassortant H3N3 avian influenza A virus in chickens

The novel avian influenza viruses(AIVs)can cause serious economic losses to the poultry industry. Systematic surveillance of novel AIVs in poultry is essential for control of avian influenza. In the present research, we isolated H3N3 subtypes AIVs from chicken farms reporting illness in China during 2022-2023. All of these chickens showed respiratory disease signs and a 10%-40% reduction in egg production. Epidemiological surveys, virus isolation and identification, sequence analysis, pathogenicity and airborne transmissibility in chickens of representative viruses isolated were conducted. The results showed that: 1)In December 2022, H3N3 AIVs was first found in a layer chicken flock in Eastern China, and the virus was transmitted to multiple provinces with high density chicken populations in a short time. The disease group was mainly in laying hens, with high morbidity, and low mortality(1%-5%), which mainly caused an acute decline in the egg production rate(10%-40%). 2)Sequence analysis showed that the novel H3N3 AIVs were evolving as a triple reassortment event, which bearing H3N8-derived HA gene, H10N3-derived NA gene and H9N2-derived internal genes. 3)Similar to the H3N8 virus, the novel H3N3 AIVs were highly susceptible to SPF chickens. The virus replicated efficiently in the turbinate, trachea and lung and infected chickens showed pathological damage. 4)H3N3 viruses were airborne transmission among chickens, whereas H3N8 viruses were not. In conclusion, the novel reassortant H3N3 viruses show serious pathogenicity and airborne transmissibility in chickens. Therefore, comprehensive surveillance of H3N3 AIVs in domestic poultry is imperative and control of the virus endemic is needed.