| Infectious bronchitis(IB)is a viral disease caused by Infectious bronchitis virus(IBV)in chickens,which is an acute and highly contagious disease that causes huge economic losses to the farming industry.Gyrovirus 3(Gy V3)is one of the pathogens causing Transmissible viral proventriculitis(TVP)in chickens.Chicken parvovirus(Ch PV)is one of the pathogens that cause stunting and dwarfism syndrome(RSS)in chickens.In recent years,Ch PV and Gy V3 have been widely prevalent in chickens in China,and IBV occurs from time to time,however,molecular epidemiological studies on Gy V3 and Ch PV have not been reported in Fujian Province.Based on this,in this study,a total of 535 diseased materials were collected from 55 randomly selected chicken farms in Nanping,Fuzhou and Longyan cities of Fujian Province from September 2020 to December 2021 and tested for these three pathogens by PCR or RT-PCR.And from them,typical positive samples were selected for cloning,sequencing and analysis of S1 gene of IBV,Gy V3 VP2 gene and Ch PV NS1 gene,respectively,as well as the isolation and identification of the above three viruses.The test results showed that there were 2 IBV positive fields,with a field positivity rate of 3.64%(2/55),3 positive samples detected,and a sample positivity rate of 0.56%(3/535);22 Gy V3 positive farms,with a farm positivity rate of 40%(22/55),116 positive samples detected,and a sample positivity rate of 21.68%(116/535);Ch PV positive farms were19,the farm positivity rate was 34.55%(19/55),154 positive samples were detected,and the sample positivity rate was 28.78%(154/535).The results of epidemiological investigation showed that the detection rate of IBV was low in random samples;The high detection rates of Ch PV and Gy V3 indicated that Ch PV infection and Gy V3 infection were widespread in chicken farms in Fujian province.The S1 gene of three IBV isolates(two from Fuzhou and one from Nanping),the VP2 gene of 11 Gy V3 strains(nine from Longyan and two from Nanping)and the NS1 gene of nine Ch PV strains(two from Nanping,two from Fuzhou and five from Longyan)were obtained in this study.The results of the genetic evolutionary tree analysis of the IBV S1 gene showed that the isolates IBV-FZ-01 and IBV-FZ-02 were of LX4/QX type.01 and IBV-FZ-02 were LX4/QX type;the IBV strain IBV-NP-01 isolated from Nanning,Guangxi,and Lianyungang,Jiangsu,was more closely related to the reference strain,however,it did not belong to any of the known genotypes.The results of this study showed that new variant strains of IBV types have emerged in the province,in addition to the QX type;the results of the genetic evolutionary tree analysis of the Gy V3 VP2 gene showed that all isolates were in the same branch as the Gy V3 reference strain;the nucleotide homology of the VP2 gene of the 11 isolates and the 8 reference strains ranged from84.8% to 99.8%.The experimental results showed that the Gy V3 VP2 gene was relatively conservative and the differences between the VP2 genes of strains from different regions were not obvious;the genetic evolutionary tree analysis of Ch PV NS1 gene showed that all isolates from three regions were closely related to the Guangxi reference strain;Longyan isolate LY-05 was in the same branch with three Korean reference strains;isolate LY-03 was related to the reference strain from Hungary The nucleotide homology between the nine isolates and the reference strain ranged from 90.8% to 99.9%.The results of this study indicate that the nucleotide homology between Ch PV NS1 genes and the proximity of the relatives are not affected by geographical differences.In summary,the presence of IBV(QX/LX4 type)and variant strains of IBV in some areas of Fujian Province was found by testing535 clinical samples,and it was also confirmed that Gy V3 and Ch PV were widely present in chicken farms in some areas of Fujian Province.In this study,we also found that the VP2 gene of Gy V3 was highly conserved and geographical differences did not lead to changes in the VP2 gene.In addition,genetic analysis of the NS1 gene of Ch PV in some areas of Fujian Province showed that it has a high degree of similarity to other Ch PV strains prevalent around the world.This study provides a reference for the prevention and control of IBV,Gy V3 and Ch PV infection in Fujian Province and subsequent studies. |
