Avian metapneumoviruses expressing Infectious Bronchitis virus genes are stable and induce protection

Abstract

The study investigates the ability of subtype A Avian metapneumovirus (AMPV) to accept foreign genes and be used as a vector for delivery of Infectious bronchitis virus (IBV) QX genes to chickens. Initially the GFP gene was added to AMPV at all gene junctions in conjunction with the development of cassetted full length DNA AMPV copies. After recombinant virus had been recovered by reverse genetics, GFP positions supporting gene expression while maintaining virus viability in vitro, were determined. Subsequently, either S1 or nucleocapsid (N) genes of IBV were positioned between AMPV M and F genes, while later a bivalent recombinant was prepared by inserting S1 and N at AMPV MF and GL junctions respectively. Immunofluorescent antibody staining showed that all recombinants expressed the inserted IBV genes in vitro and furthermore, all recombinant viruses were found to be highly stable during serial passage. Eyedrop inoculation of chickens with some AMPV-IBV recombinants at one-day-old induced protection against virulent IBV QX challenge 3 weeks later, as assessed by greater motility of tracheal cilia from chickens receiving the recombinants. Nonetheless evidence of AMPV/IBV seroconversion, or major recombinant tracheal replication, were largely absent.

Development and application of reporter-expressing mononegaviruses: Current challenges and perspectives

“…Tokusumi et al have shown in a study where they inserted the sequence encoding for secreted alkaline phosphatase into all possible genome positions that this seems to be the case for Sendai virus (Tokusumi et al, 2002). Also, this idea is further supported by other studies in paramyxoviruses comparing different insertion positions (Falchieri et al, 2013; von Messling et al, 2004; Zhao and Peeters, 2003). However, in a study with recombinant VSV, where the authors inserted a 661 nucleotide long non-coding ATU at each of the gene-junctions, the authors only observed a strong attenuation when the ATU was inserted between the N and P gene (first gene junction), and no attenuation in vitro when any of the other gene junctions were used (Wertz et al, 2002).…”

Genetic Heterogeneity among Chicken Infectious Anemia Viruses Detected in Italian Fowl

“…Vaccine persistence, circulation and reversion to virulence have also been frequently reported for other empirically attenuated avian vaccines developed to control immunosuppressive or respiratory diseases [ 52 , 53 , 54 ]. Next-generation vaccines, with improved stability and safety, are currently under study and development for most avian pathogens and, in the future, they will likely replace traditional vaccines [ 55 , 56 , 57 , 58 ].…”

A Recombinant La Sota Vaccine Strain Expressing Multiple Epitopes of Infectious Bronchitis Virus (IBV) Protects Specific Pathogen-Free (SPF) Chickens against IBV and NDV Challenges

“…Thus, it is necessary to develop a novel bivalent vaccine protect against NDV and IBV. In recent decades, attempts have been made to develop recombinant vaccines using NDV [48][49][50], adenovirus [51], duck enteritis virus [52], and avian metapneumovirus [53] viral backbones expressing the S1 or S2 portion of the IBV spike gene with differing levels of protection from IBV challenge. Among them, the NDV vector shows great promise due to its excellent characteristics, such as rapid and long-lasting immune response, low production costs, convenience of administration, and genetic stability [45].…”