Abstract
Vaccination of hens against influenza leads to the transfer of protective maternally-derived antibodies (MDA) to hatchlings. However, little is known about the transfer of H7N3 vaccine-induced MDA. Here, we evaluated transfer, duration, and protective effect of MDA in chickens against H7N3 HPAIV. To generate chickens with MDA (MDA (+)), 15-week-old White Leghorn hens were vaccinated and boosted twice with an inactivated H7N3 low pathogenic avian influenza virus vaccine, adjuvanted with Montanide ISA 71 VG. One week after the final boost, eggs were hatched. Eggs from non-vaccinated hens were hatched for chickens without MDA (MDA (−)). Both MDA (+) and MDA (−) hatchlings were monitored weekly for antibody levels. Anti-HA MDA were detected by hemagglutination inhibition assay mostly until day 7 post-hatch. However, anti-nucleoprotein MDA were still detected three weeks post-hatch. Three weeks post-hatch, chickens were challenged with 106 EID50/bird of Mexican-origin H7N3 HPAIV. Interestingly, while 0% of the MDA (−) chickens survived the challenge, 95% of the MDA (+) chickens survived. Furthermore, virus shedding was significantly reduced by day 5 post-challenge in the MDA (+) group. In conclusion, MDA confers partial protection against mortality upon challenge with H7N3 HPAIV, as far as three weeks post-hatch, even in the absence of detectable anti-HA antibodies, and reduce virus shedding after challenge.
Highlights
IntroductionInfluenza A virus (IAV) infections of poultry have severe repercussions to the poultry industry
Influenza A virus (IAV) infections of poultry have severe repercussions to the poultry industry.Infections with low pathogenic avian influenza virus (LPAIV) are commonly associated with reduced feed conversion rates, weight loss, decreased egg production, and secondary infections
Eight-week-old, commercial avian influenza-free White Leghorn poults were purchased from VALO BioMedia North America (Adel, IA, USA), and used in this study for the generation of maternally-derived antibodies (MDA) positive (MDA (+)) and MDA
Summary
Influenza A virus (IAV) infections of poultry have severe repercussions to the poultry industry. Infections with low pathogenic avian influenza virus (LPAIV) are commonly associated with reduced feed conversion rates, weight loss, decreased egg production, and secondary infections. Flocks infected with highly pathogenic avian influenza virus (HPAIV) usually show high mortality rates that can decimate an entire flock. Outbreaks of LPAI and HPAI cause important economic losses to the poultry industry due to expenses associated with culling and quarantine, emergency vaccination programs, and loss of consumer confidence, among other issues. Vaccines 2019, 7, 163 are of the H5 and H7 subtypes because of their potential to mutate into HPAIVs. Outbreaks in poultry caused by H5 and H7 subtype LPAIV and HPAIV strains are reportable to the World Animal
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