Comparative Analysis Of Host Acquired And Innate Immune Responses Induced By Two Different Newcastle Disease Viruses

In this study,based on the identification and biological characteristics resear,ch of a Newcastle disease virus(NDV)strain preserved in our laboratory(named Lasota.P2M1),the difference of host acquired immunity and innate immunity between Lasota.P2M1 and standard NDV strain was explored.The results were as follows.1 Analysis of the Biological Characteristics of Lasota.P2M1In order to identify the the purity and partial biological characteristics of Lasota.P2M1,whose hemagglutination titers were significantly higher than that of the standard Lasota strain,RT-PCR was used to eliminate the presence of other common avian viruses and electron microscopy was utilized to observe the structure of the virus particles.Moreover,the viral RNA was extracted for whole genome sequencing and the sequences were compared with the published standard strain.The results showed that,the virus solution of Lasota.P2M1 didn't contain avian influenza virus(AIV),infectious bursal disease virus(IBDV),egg drop syndrom virus(EDSV).The virus particles of Lasota.P2M1 were spherical,and approximately 200-300 nm and had spikes on its capsule,which was morphologically consistent with NDV.Compared with the standard Lasota virus,5 genome mutations and 3 structural protein mutations were found in Lasota.P2M1,which may result in the increasement of hemagglutination titers.2 Different Host Acquired Immune Responses Induced by two Different NDVIn order to study the different acquired immune response induced by standard Lasota strain and Lasota.P2M1,two groups of 1-week-old chickens immunized with either Lasota or Lasota.P2M1 were challenged with velogenic NDV 2 weeks post-immunization(wpi).The survival rate of Lasota.P2M1 group(60%)was significantly higher than that of standard Lasota group(40%).Lasota.P2M1 group had less virus replication and less virus shedding.In addition,chickens immunized with Lasota.P2M1 produced higher titers of IgG,SIgA,NDV-specific HI and NDV-neutralizing antibody.In conclusion,the Lasota.P2M1 had a better protective effect on chickens compared with the standard Lasota strain via inducing stronger humoral immunity,mucosal immunity,and NDV-specific HI and neutralizing antibodies,which was probably related to the mutations of the genome.The immunological characteristics changes of Lasota.P2M1 may be applied in vaccine development.3 Different Host Innate Immune Responses Induced by two Different NDVIn order to compare the different host innate immune responses induced by two NDVs(standard Lasota strain or mutation Lasota.P2M1 strain),embryo fibroblasts cell line(DF-1)cells were challenged with the two viruses,respectively.Then,the pattern recognition receptor(TLR3,7 and MDA5),transcription factor(IRF3)and cytokines were detected by Real-time PCR,Western blot and protein chip,etc.The results showed that the mRNA and protein expression of TLR3,7 and MDA5 induced by Lasota were significantly higher than that of Lasota.P2Ml(P<0.05),so was the expression of IRF3,the phosphorylated IRF3 and most of the cytokines(31/40)in the supernatant of DF-1 cells after 12 h infection.These indicated that there were different host innate immune responses between these two viruses,which may explain why Lasota.P2M1 had high titer in chick embryo.