Optimized clade 2.3.2.1c H5N1 recombinant-vaccine strains against highly pathogenic avian influenza

A/Puerto Rico/8/34 (PR8)-derived recombinant viruses have been used for seasonal flu vaccines; however, they are insufficient for vaccines against some human-fatal H5N1 highly pathogenic avian influenza (HPAI) viruses (HPAIV) due to low productivity. Additionally, the polymerase basic 2 (PB2) protein, an important mammalian-pathogenicity determinant, of PR8 possesses several mammalian-pathogenic mutations. We previously reported two avian PB2 genes (01310 and 0028) related to efficient replication in embryonated chicken eggs (ECEs) and nonpathogenicity in BALB/c mice. In this study, we generated PR8-derived H5N1 recombinant viruses harboring hemagglutinin (attenuated) and neuraminidase genes of a clade 2.3.2.1c H5N1 HPAIV (K10-483), as well as the 01310 or 0028 PB2 genes, and investigated their replication and immunogenicity. Compared with a control virus harboring six internal PR8 genes (rK10-483), the recombinant viruses possessing the 01310 and 0028 PB2 genes showed significantly higher replication efficiency in ECEs and higher antibody titers in chickens. In contrast to rK10-483, none of the viruses replicated in BALB/c mice, and all showed low titers in Madin-Darby canine kidney cells. Additionally, the recombinant viruses did not induce a neutralization antibody but elicited decreased protective immune responses against K10-483 in mice. Thus, the highly replicative and mammalian nonpathogenic recombinant H5N1 strains might be promising vaccine candidates against HPAI in poultry.

Experimental infection of dogs with highly pathogenic avian influenza virus (H5N8)

During the highly pathogenic avian influenza (HPAI) H5N8 virus outbreak in Korea, a dog in layer farm contaminated by H5N8 was reported seropositive for HPAI H5N8. To investigate the possibility of adaptation and transmission of HPAI H5N8 to dogs, we experimentally inoculated dogs with H5N8. Viral genes were weakly detected in nasal swabs and seroconversions in inoculated and contact dogs. Although the H5N8 virus did not induced severe clinical signs to dogs, the results suggest that surveillance of farm dogs should continue as a species in which the avian influenza virus may acquire infectivity to mammals through frequent contact with the virus.

Application of Diagnostic Microarray Technique in Subtyping and Pathotyping of Avian Influenza Viruses Isolated in Mongolia

Asian-lineage H5 highly pathogenic avian influenza (HPAI) viruses have caused continuous outbreaks in poultry and wild birds. Development of rapid and accurate diagnostic methods is needed for preventing further spread of the virus and reducing the time required for eradication of the virus. We developed a low-density microarray for the rapid detection and identification of avian influenza virus subtypes H5, H7, and H9 and their pathotypes in a previous study. In the present study, we evaluated previously developed diagnostic microarray using avian influenza viruses isolated in Mongolia, including H5 HPAI viruses. All H5 HPAI viruses isolated in Mongolia were shown as H5-specific and highly pathogenic pattern in the microarray. H2, H3 and H12 viruses isolated in Mongolia used in this study did not show any H5, H7 and H9 patterns. These results indicated that this diagnostic microarray has enormous potential for the rapid subtyping and pathotyping of influenza viruses, including viruses isolated in Mongolia.

Viscerotropic velogenic Newcastle disease virus replication in feathers of infected chickens

Newcastle disease viruses (NDVs) cause systemic diseases in chickens with high mortality. However, little is known about persistence of NDVs in contaminated tissues from infected birds. In this study, we examined viral replication in the feather pulp of chickens inoculated with viscerotropic velogenic NDV (vvNDV) genotype VII. Reverse transcription real-time PCR and immunohistochemistry were used to investigate viral persistence in the samples. vvNDV was detected in the oropharynx and cloaca and viral antigens were detected in the feathers, suggesting that feathers act as sources of viral transmission.

Intranasal Administration Model for Evaluating Protection Against Influenza Virus in Mice

Antiviral activity against Influenza virus of 14 Lactobacillus species isolated from food was monitored. Lactobacillus species were isolated from traditional Korean fermented food. Each live Lactobacillus was administered into the nasal cavity of SPF 6-week-old BALB/c mice. After the Lactobacillus treatment, Influenza virus (A/NWS/33/H1N1) was inoculated to each mouse. Clinical signs and mortality was monitored for 21 days. Each Lactobacillus strain showed various level of antiviral activity against Influenza virus. As a result of this study, this mouse experiment model, including intranasal treatment of live Lactobacillus species, could be effective model in evaluating immunomodulatory response of probiotics against respiratory viruses.