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Interaction between avian influenza subtype H9N2 and Newcastle disease virus vaccine strain (LaSota) in chickens.

ABSTRACT: BACKGROUND:H9N2 avian influenza virus is endemic in Egyptian poultry flocks. The role of the live viral vaccines such as LaSota in exaggeration of the clinical picture of H9N2 infection under field conditions is significantly important leading to severe economic losses due to higher mortality and lower growth performance. This experiment was designed to identify the possible interaction between experimental infection with H9N2 virus and NDV live vaccine (LaSota strain) in broiler chickens. Six groups each of 20 broiler chicks were used. Three groups (G1-3) were infected with H9N2 and vaccinated with LaSota, 3?days before, at the same day or 3?days post vaccination (dpv), while the remaining groups (G4-6) were non-vaccinated infected, vaccinated non-infected and non-vaccinated non-infected. RESULTS:The highest mortality rate (37.5%) was noticed in chickens of G1 (H9N2 infected 3?days prior LaSota vaccination). Also, this bird group had the most severe clinical signs, histopathological lesions and the longest viral shedding for 9?days post infection (dpi). In the 2nd and 3rd groups, the mortality rate was the similar (31.2%) with less pronounced clinical signs, histopathological lesions and H9N2 shedding was for only 6 dpi with the least shedding quantity in chickens of G3. The control non-vaccinated infected chickens (G4) had 18.7% mortality with the least degree of clinical signs, lesions and the highest viral shedding quantity but only for 6 dpi. At 35?days of age, there was a statistical significant decrease (P?

SUBMITTER: Ellakany HF

PROVIDER: S-EPMC6245631 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Interaction between avian influenza subtype H9N2 and Newcastle disease virus vaccine strain (LaSota) in chickens.

Ellakany Hany F HF Gado Ahmed R AR Elbestawy Ahmed R AR Abd El-Hamid Hatem S HS Hafez Hafez M HM Abd El-Hack Mohamed E ME Swelum Ayman A AA Al-Owaimer Abdullah A Saadeldin Islam M IM

BMC veterinary research 20181120 1

<h4>Background</h4>H9N2 avian influenza virus is endemic in Egyptian poultry flocks. The role of the live viral vaccines such as LaSota in exaggeration of the clinical picture of H9N2 infection under field conditions is significantly important leading to severe economic losses due to higher mortality and lower growth performance. This experiment was designed to identify the possible interaction between experimental infection with H9N2 virus and NDV live vaccine (LaSota strain) in broiler chicken ...[more]

PMID: 30458777

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Project description:H9N2 avian influenza virus has spread worldwide, and vaccination with an inactivated virus is currently the major prevention method in China. To further understand the effect of the selection pressure from antibodies on the evolution of H9N2 avian influenza virus, F/98 (A/Chicken/Shanghai/F/98), which is the vaccine representative of H9N2 avian influenza virus in East China, was used for serial passaging for 20 generations in chickens with and without vaccination. After plaque purification from trachea and lung tissues, 390 quasispecies were obtained. The second-generation quasispecies under the selection pressure of vaccine antibodies had undergone 100% antigen variation, while after passaging to the fifth generation, only 30-40% of the quasispecies displayed antigen variation when there was no selection pressure of vaccine antibodies, implying that the selection pressure of vaccine antibodies promotes the antigen variation of F/98. We found for the first time that there were three mutation hotspots in the HA genes of the quasispecies under the selection pressure of vaccine antibodies, which were K131R, A168T, and N201D. Moreover, under the selection pressure of vaccine antibodies, 10 amino acids (67-76) of the NA protein of all quasispecies were deleted, and PB2 of the quasispecies had undergone a high-frequency R355K mutation. However, without selection pressure of vaccine antibodies, NP had undergone two high-frequency mutations, namely, V186I and L466I, and a high-frequency mutation of L77I appeared in the NS gene. This result shows that the vaccine antibody selection pressure could control and regulate gene variation of the F/98 virus. Compared to that of the parental virus F/98, the EID50 of the twentieth passaged virus under the selection pressure of vaccine antibodies did not change, while the EID50 of the twentieth passaged virus without selection pressure of vaccine antibodies was significantly enhanced by 794 times. Furthermore, the twentieth passaged virus with selection pressure from vaccine antibodies lost its lethal ability in embryonated chicken eggs, whereas the EID50 of the twentieth passaged virus without selection pressure of vaccine antibodies increased to 6.3 times that of the F/98 strain. All the above results show that the selection pressure of vaccine antibodies promotes the antigen variation of H9N2 avian influenza virus and plays a role in regulating and controlling gene mutation of H9N2 avian influenza virus.

Dataset Information

Interaction between avian influenza subtype H9N2 and Newcastle disease virus vaccine strain (LaSota) in chickens.

Publications

Interaction between avian influenza subtype H9N2 and Newcastle disease virus vaccine strain (LaSota) in chickens.

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