科研动态

为了解鸡传染性支气管炎病毒（IBV）在我国的流行规律，通过RT-PCR方法，对2019—2021年从我国29个省级行政区送检的38 442份疑似IBV感染样品进行病原检测和鉴定，对检出的阳性样品进行S1基因测序分型，然后对检测结果进行时间、空间和群间统计分析。结果显示：共检出6 436份IBV阳性样本，阳性检出率为16.7%。2019—2021年的IBV阳性检出率分别为12.5%、16.4%、21.0%，呈逐年增长趋势：阳性检出率呈现一定的季节性变化特点，7—9月检出率（11.3%~15.4%）较低，而3—6月（17.3%~19.3%）和10—12月（17.5%~19.0%）较高。全国29个省级行政区中有27个检出阳性样品，其中东部和中部家禽养殖密集区阳性检出率较高，而西部和北部地区较低。白羽肉鸡阳性检出率最高（28.9%），肉种鸡阳性检出率最低（5.0%），0~6周龄阶段IBV感染较为严重。共检出5种基因型，其中QX型（66.5%）、GVI型（27.7%）占比较高，为当前流行的优势基因型；不同品种鸡群中流行的基因型存在一定差异，白羽肉鸡群中以QX和GVI型为主，而其他鸡群中流行的基因型较为复杂；QX型0~3周龄（33.2%）、GVI型3~6周龄（66.4%）阳性检出数量占比较高，6周龄以后占比均较低（＜14.0%）。结果表明：我国鸡群中IBV感染普遍，尤其是家禽养殖密集区，且流行呈逐年加重趋势；冬春或秋冬季节多发，小日龄鸡群感染严重；流行基因型复杂，以QX型和GVI型多见。结果提示，我国的IB防控面临较大压力与挑战，需要加强优势基因型疫苗的研发，重点做好小日龄鸡群的IB防控。

Epidemiological Investigation on Avian Infectious Bronchitis in 29 Provincial Administrative Regions of China from 2019 to 2021

In order to identify the prevalence rule of avian infectious bronchitis virus（IBV）in China，38 442 samples with suspected IBV infection submitted by 29 regions at provincial levels from 2019 to 2021 were detected and identified by RT-PCR. The S1 genes of positive samples were sequenced and typed，and then the results were statistically analyzed from the aspects of time，space and intergroup. The results showed that 6 436 IBV positive samples were detected，with the positive detection rate of 16.7%.The positive detection rates of IBV for the three years were 12.5%，16.4% and 21.0% respectively，tending to increase year by year：the positive detection rate changed with seasons to certain extent，which was lower from July to September（11.3% to 15.4%），and higher from March to June（17.3% to 19.3%）and October to December（17.5% to 19.0%）. Positive samples were detected from 27 out of 29 regions，the detection rates were higher in intensive poultry areas in the eastern and central regions，and lower in the western and northern regions. The detection rate of white feather broilers was highest（28.9%），and that of broiler breeders was lowest（5.0%）. The infection with IBV was more serious in chickens at the age of 0~6 weeks. Five genotypes were detected，especially QX（66.5%）and GVI（27.7%）that were dominant genotypes；the prevalent genotypes were different in different breeds，QX and GVI were the main genotypes in white feather broiler flocks，while the prevalent genotypes were complex in other flocks；the positive rates of QX and GVI were higher in the flocks at 0 to 3 weeks old（33.2%）and 3 to 6 weeks old（66.4%），and lower in those at more than 6 weeks old（＜14.0%）. In conclusion，IBV was widely distributed in chicken flocks in China，especially in intensive areas where the prevalence tended to increase year by year；it occurred frequently in winter，spring or autumn，and was serious in the flocks at young day old；the prevalent genotypes were complex，especially QX and GVI were common. In conclusion，there was a huge pressure and challenge to prevent and control IB in China，thus it was necessary to strengthen the development of vaccines of dominant virus genotypes，and a priority should be given to IB control of chicken flocks at young day old.

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