Generation and Evaluation of Recombinant Thermostable Newcastle Disease Virus Expressing the HA of H9N2 Avian Influenza Virus.

Xiaorong Zhang,Yongzhong Cao,Yantao Wu,Yin Chen,Chenchen Meng,Zongyi Bo,Chengcheng Zhang

doi:10.3390/v13081606

Abstract

H9N2 avian influenza virus (AIV) has become endemic in many countries, causing great economic losses when co-infected with other pathogens. So far, several live vaccines based on Newcastle disease virus (NDV) vectors expressing influenza hemagglutinin (HA) have been developed. However, the thermostable recombinant NDV is rarely reported. In this study, using a thermostable NDV rAHR09 strain as the vector, three recombinant NDVs expressing native HA, chimeric HA ectodomain with transmembrane domain/C-terminal cytoplasmic tail domain from fusion protein of NDV, and HA ectodomain were generated, designated rAHR09-HA, rAHR09-HAF, and rAHR09-HAE. The MDT value of three recombinant NDVs was above 120 h, their ICPI value was about 0.03, and the recombinant NDVs were still infectious when treated for 100 min under 56 °C, which demonstrated that the recombinant NDVs kept the lentogenic and thermostable nature of rAHR09. The immunization data showed that rAHR09-HA and rAHR09-HAF induced a higher HI antibody titer against H9N2 AIV and NDV. After being challenged with H9N2 AIV, the rAHR09-HA and rAHR09-HAF could significantly reduce the virus shedding in cloacal and tracheal swab samples. Our results suggest that rAHR09-HA and rAHR09-HAF might be vaccine candidates against H9N2 AIV.

Highlights

H9N2 avian influenza virus (AIV) has low pathogenicity to chickens, only causing mild clinical symptoms
Passages 5, 10, 15, and 20 were chosen and propagated in CEF cells to check the expression of the HA gene using the WB method, and the results showed that all the passages of the three recombinant rAHR09-HA (Figure 3D), rAHR09-HAF (Figure 3E), and rAHR09-HAE (Figure 3F) could express the HA protein, which indicated that the three recombinant Newcastle disease virus (NDV) could stably express the HA gene
The results showed that all chickens remained healthy without any clinical signs after they were challenged with H9N2 AIV

Summary

Introduction

H9N2 avian influenza virus (AIV) has low pathogenicity to chickens, only causing mild clinical symptoms. When co-infected with other pathogens, it can cause a synergistic pathogenic effect and lead to severe clinical symptoms and higher mortality [1,2]. Despite biosecurity measures, vaccination is still the main method used in the control of H9N2 AIV [3,4,5]. There are several kinds of virus vectors that have been used for the development of an AIV vaccine, such as fowlpox virus and Marek’s disease virus [6,7,8]. The virus vector-based vaccine can facilitate the immune procedure to reach the goal of “one immunization, multiple protection”. There have been several reports that have showed that the NDV can be used to express the HA protein of AIV [9,10,11,12], and the replacement of the transmembrane (TM)/C-terminal cytoplasmic tail domain (CTD) of AIV HA protein with that of NDV F protein could improve the incorporation of the AIV

Methods

Results

Discussion

Conclusion