Comparison Between Class ? NDV And Class ? NDV In Aerosol Transmission

Objective:Aerosol transmission is the main mode of transmission of Newcastle disease virus(NDV),but past research has been directed at Class II NDV.The main purpose of this topic is to investigate whether Class I NDV can transmit through aerosol and compare the airborne sexual transmission of Class I NDV and Class II NDV.Methods:In this study,a new model of NDV aerosol spread under experimental conditions was established.Two positive and negative pressure isolators A and B were connected through a single pipe,and SPF chickens were housed in the isolators.They were randomly divided into artificial infection groups.Contact infection group,aerosol infection group.The artificial infection group and the contact infection group were reared in the isolator A,and the aerosol infection group was reared in the isolator B.Chickens in the artificially infected group were inoculated with Class I NDV NX1069 strain at 20 days of age.At the same time,the same test was performed at the isolator C and the isolator D,but the inoculation virus was Class II NDV Lasota strain.Air samples from the isolators and cotton swabs were collected on the 1,2,3,5,7,9,12,15,18,21,24,27,30,35,40 dpi.blood samples of the experimental chickens were collected by wing vein blood sampling at 7,14,21,28,35and 40 dpi.Air samples were analyzed for virus aerosol concentrations by plaque counting;cotton swab samples were analyzed by qRT-PCR for detoxification of test chickens;and HI samples were used for blood samples to detect NDV antibody titers in serum.According to the progress of the experiment,the chickens were subjected to necropsy and tracheal samples were collected.The Elisa method was used to analyze the SIgA levels in the tracheal mucosa and 16S rRNA high-throughput sequencing was used to analyze the bacterial composition in the tracheal mucosa.Results:The NDV aerosol propagation test results showed that Class I NDV virus aerosol was first detected in isolator A at 5 dpi.Class I NDV virus aerosols in isolator A peaked at 18.dx 103 PFU/m3 at 18 dpi.Class ? NDV aerosols were detected for the first time at 7 dpi,but peaked at 18 dpi and peaked at 13.01 × 103 PFU/m3.Class I NDV Isolator B first detected viral aerosol at 7dpi,but Class ? NDV Isolator D first detected viral aerosol at 9dpi.The swab test results showed that Class ? NDV aerosol infected chickens were detoxified at 9 dpi while Class II NDV aerosol infection groups were detoxified at 15 dpi.The results of the HI test showed that the antibody titres produced by the two Newcastle disease viruses were very high,with a maximum of 27 or more.The results of SIgA analysis showed that both Class I NDV contact and aerosol transmission can increase the level of tracheal mucosal SIgA significantly.There was no significant difference between contact and aerosol transmission.The results of high-throughput sequencing showed that the changes in contact of Class I NDV contact with aerosols caused changes in the tracheal mucosal flora.Both the contact group and the aerosol group decreased the diversity of the respiratory flora,but there were only 21 species of the same respiratory tract in the aerosol group and the blank group,and 49 species in the contact group and the blank group.The difference in respiratory mucosal flora between the aerosol-infected group and the blank group was greater.The level of bacteria abundance test results show that the bacteria in the tracheal mucosa increased after contact infection are mostly conditional bacteria:such as Escherichia-Shigella,etc.,while the aerosol infection group has the greatest increase in the abundance of bacteria Lactobacillus.Conclusion:Class I NDV can form viral aerosols,and the virus aerosols can diffuse into adjacent isolators.In this experiment,the Class I NDV formed earlier than the Class II NDV virus aerosol,and the Class I NDV aerosol infected group also had earlier detoxification.Infection of Class I NDV by different routes of transmission can significantly increase the level of tracheal mucosal SIgA.The aerosol infection group will have a greater change in the tracheal mucosal flora,but direct contact infections are more likely to be secondary to the presence of pathogenic bacteria on the tracheal mucosa.