Surveilance Of Infection Of H9-AIV,NDV,IBV,ILTV And FAV In Laying Hens Of Shandong Province

With the rapid development of China's economy,animal husbandry in Shandong Province has entered a new period of development.In order to meet the requirements of the development of the new era,ensure food hygiene and safety,and clarify the epidemic dynamics of hens and chickens in our province,as well as virus variability,Therefore,a systematic epidemiological survey of H9-AIV,NDV,IBV,ILTV,and FAV infections in laying hens in Shandong Province was conducted.According to the survey results,we should grasp the latest trend of laying hens disease in our province,so as to develop scientific and reliable prevention and control measures to ensure the safe and healthy development of laying hens in our province.According to the HA gene of H9-AIV,the F gene of NDV,the S1 gene of IBV,the TK gene of ILTV,and the whole or part of the hexon gene of FAV,5 pairs of specific primers were designed and synthesized to verify the PCR and RT-PCR detection methods.671 samples of laying hens collected from Tai'an,Jining and Heze in Shandong were detected by using the method.The results showed that the positive rate of five pathogens in the samples was 294,and the positive rate was 43.8%.The positive rates of H9-AIV,NDV,IBV,ILTV and FAV were 36.4%,0.0%,10.0%,7.2% and 3.0%,respectively.The above results showed that the infection rate of H9-AIV was the highest,the infection rate of IBV and ILTV was high,FAV infection rate was low,and no NDV infection was found.Further analysis of the detected results showed that the mixed infection in the samples appeared in three ways of infection: H9-AIV+IBV,H9-AIV+ILTV and H9 AIV+FAV.Among the 83 mixed infection samples,the number of H9-AIV+ILTV infection was the highest,accounting for 63% of the positive samples;the number of H9-AIV+IBV infection was 33,accounting for 40% of the positive samples,and the number of H9-AIV+FAV infection was 2,accounting for 2% of the positive samples.By analyzing the age distribution of pathogenic infection,it was found that 109 H9-AIV positive infections,46 positive H9-AIV samples and 96 H9-AIV positive samples at the laying period were found in the brood stage,and H9-AIV could infect every day old laying hens with the highest infection rate at the brooding period and the laying period.There were 49 IBV positive samples at the brood stage,18 IBV positive samples at the growth stage,and no IBV positive samples in the laying period.IBV infection occurred mainly in the brood stage and the growth stage.ILTV detected only 48 positive samples in the egg producing period,indicating that ILTV mainly harms the adult laying hens,and the infection rate of the brooding and breeding period was very low.There were 10 FAV positive samples at the brood stage and the growth stage,and no FAV positive samples were detected in the laying period.FAV infection was frequently seen in laying hens at the brood stage and at the growth stage.By analyzing the pathogen infection in different seasons,the infection of H9-AIV,IBV and ILTV occurred in spring,summer,autumn and winter,and the number of positive infections in different seasons of H9-AIV were 87,33,71,and 53,respectively.IBV,the number of positive infections in different seasons was 28,4,10 and 25,respectively.The number of ILTV positive infections in different seasons was 10,4,12 and 22 respectively.FAV infection mainly occurred in the two seasons of summer and autumn.The number of positive infections was 16 and 4,respectively.There was no positive infection in two seasons in spring and winter.No NDV positive infection.The epidemic trends of H9-AI,IB and ILT are approximately the same,with obvious seasonal characteristics.The incidence of the three seasons in spring,autumn and winter is relatively high,especially in the early winter and early summer and early summer and early autumn.The incidence of FAV infection is contrary to that of H9-AI,IB and ILT.The incidence is the highest in summer,while the lowest in winter and spring.The gene homology and genetic evolution of 5 strains of H9-AIV,4 IBV,4 ILTV,2 FAV and domestic and foreign reference strains were analyzed by using the LASERGENE software.The results showed that the H9-AIV isolates in our province were highly homologous,and were highly homologous with Y280 strains and located in the same branch,far from G1 and Y439 branches.The IBV isolates and the reference strains were significantly different.The homology of the vaccine strain H120,491 and H52 was low,and the homology of the QX and LX4 reference strains was higher.All the isolates were located in the QX genotype branch and belong to the QX genotype.The virulence gene of ILTV isolate TK is highly homologous with BeiJing E2,Throne,632,216 and other reference strains,indicating that the ILTV TK virulence gene is highly conserved and more stable.It is located in the same branch with the United States 632 strong strains,and is close to other avian herpes viruses such as MDV and HVT,and is far closer to mammalian herpes virus HHV.The relationship is far away.The hexon gene of FAV isolates is highly homologous and has the highest homology with FAV-4,which is located in FAV-4 branch.It is the main serotype of our province.In summary,H9-AIV,NDV,IBV,ILTV,and FAV infection are still the major diseases that threaten the development of laying hens in our province.They are infected or co-infected,resulting in morbidity,mortality,or reduced performance of chickens,causing significant economic losses to layer chicken breeding.