Oral Inoculation of Chickens with a Candidate Fowl Adenovirus 9 Vector

Abstract

Fowl adenoviruses (FAdVs) are a potential alternative to human adenovirus-based vaccine vectors. Our previous studies demonstrated that a 2.4-kb region at the left end of the FAdV-9 genome is nonessential for virus replication and is suitable for the insertion or replacement of transgenes. Our in vivo study showed that the virus FAdV-9⌬4, lacking six open reading frames (ORFs) at the left end of its genome, replicates less efficiently than wild-type FAdV-9 (wtFAdV-9) in chickens that were infected intramuscularly. However, the fecal-oral route is the natural route of FAdV infection, and the oral administration of a vaccine confers some advantages compared to administration through other routes, especially when developing an adenovirus as a vaccine vector. Therefore, we sought to investigate the effects of FAdV-9 in orally inoculated chickens. In the present study, we orally inoculated specific-pathogen-free (SPF) chickens with FAdV-9 and FAdV-9⌬4 and assessed virus shedding, antibody response, and viral genome copy number and cytokine gene expression in tissues. Our data showed that FAdV-9⌬4 replicated less efficiently than did wtFAdV-9, as evidenced by reduced virus shedding in feces, lower viral genome copy number in tissues, and lower antibody response, which are consistent with the results of the intramuscular route of immunization. Furthermore, we found that both wtFAdV-9 and FAdV-9⌬4 upregulated the mRNA expression of alpha interferon (IFN-␣), IFN-␥, and interleukin-12 (IL-12). In addition, there was a trend toward downregulation of IL-10 gene expression caused by both viruses. These findings indicate that one or more of the six deleted ORFs contribute to modulating the host response against virus infection as well as virus replication in vivo.

Pathogenicity and Cytokine Gene Expression Pattern of a Serotype 4 Fowl Adenovirus Isolate

“…The lack of pathological changes was not due to lack of virus replication, since virus was found in tissues and cloacal swabs of the FAdV-4 infected birds; although in numerically lower quantities than previously reported for FAdV-8 and FAdV-9 [16,11]. In both the orally and im inoculated groups, the highest numbers of viral genome copies were detected in the cecal tonsil, in agreement with our work on FAdV-8 [16].…”

Impacts of poultry vaccination on viruses of wild bird

“…Herpesvirus of turkey (HVT) and FPV are used commercially as vaccine vectors to express genes from other poultry pathogens, including AIV, IBDV, NDV and infectious laryngotracheitis virus (ILTV) ( Table 1). Fowl adenovirus (FAdV) and a number of avian herpesviruses (ILTV, MDV-1 and duck enteritis virus) have also been used experimentally as vaccine vectors [32][33][34][35][36]. The risk of vectored poultry vaccines being transmitted to wild birds may appear to be low because of the limited shedding of most vectored vaccines, but this risk could rise as a result of recombination.…”

Self-assembled star-shaped chiroplasmonic gold nanoparticles for an ultrasensitive chiro-immunosensor for viruses

“…An early detection system with high sensitivity and specicity is urgently needed to prevent the spread of diseases in the poultry sector. 27 Infectious bronchitis (IB), a coronavirus, is another important disease in chickens caused by IB virus (IBV), which is one of the primary agents of respiratory disease in chickens worldwide. Chickens infected with IBV exhibit the symptoms of gasping, coughing, rales, and nasal discharge, huddling together, and appearing depressed as well as wet droppings and increased water consumption.…”