Abstract
The H5 subtype highly pathogenic avian influenza virus (HPAIV) has been introduced to South Korea every 2 or 3 years via wild migratory waterfowls, causing devastating damages to the poultry industry. Although most damages and economic losses by HPAIV are focused on chicken layers, domestic ducks are known to play a major role in the farm-to-farm transmission. However, most HPAIV vaccine studies on poultry have been performed with oil-emulsion inactivated vaccines. In this study, we developed a live recombinant Newcastle disease virus (NDV)-vectored vaccine against H5 HPAIV (rK148/ES2-HA) using a previously established NDV vaccine strain (K148/08) isolated from a wild mallard duck. The efficacy of the vaccine when administered via the oculonasal route or as a spray was evaluated against lethal H5 HPAIV infection in domestic ducks and chickens. Oculonasal inoculation of the rK148/ES2-HA in chickens and ducks elicited antibody titers against HPAIV as early as 1 or 2 week after the single dose of vaccination, whereas spray vaccination in ducks elicited antibodies against HPAIV after the booster vaccination. The chickens and ducks vaccinated with rK148/ES2-HA showed high survival rates and low viral shedding after H5N6 HPAIV challenge. Collectively, vaccination with rK148/ES2-HA prevented lethal infection and decreased viral shedding in both chickens and ducks. The vaccine developed in this study could be useful in suppressing the viral shedding in H5 HPAIV outbreaks, with the ease of vaccine application and fast onset of immunity.
Highlights
Influenza virus type A is an RNA virus belonging to the family Orthomyxoviridae and can infect a variety of host species, including humans, pigs, and birds
The ES2-HA gene was inserted between the P and M junctions and ligated into the pK148 plasmid to construct pK148/ES2HA (Figure 1)
The rescue of rK148 and rK148/ES2-HA viruses was verified by using the hemagglutination assay, and the HA gene was verified by using PCR after three consecutive passages in 9–11-day-old embryonated SPF chicken eggs (Figure 2)
Summary
Influenza virus type A is an RNA virus belonging to the family Orthomyxoviridae and can infect a variety of host species, including humans, pigs, and birds. Wild birds and poultry are the major factors in the transmission of avian influenza [1, 2]. NDV-Vectored H5 HPAIV Vaccine can be classified depending on the antigenic diversity of the two surface glycoproteins, namely, hemagglutinin (HA) and neuraminidase (NA); there are 16 subtypes from H1 to H16, and 9 subtypes from N1 to N9 [2]. The combination of these two proteins theoretically allows 144 subtypes to exist [3]. The majority of HPAIVs originate from the H5 or H7 subtypes [1]
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