Youn-Jeong Lee

Characterization of Highly Pathogenic H5N1 Avian Influenza A Viruses Isolated from South Korea

ABSTRACT An unprecedented outbreak of H5N1 highly pathogenic avian influenza (HPAI) has been reported for poultry in eight different Asian countries, including South Korea, since December 2003. A phylogenetic analysis of the eight viral genes showed that the H5N1 poultry isolates from South Korea were of avian origin and contained the hemagglutinin and neuraminidase genes of the A/goose/Guangdong/1/96 (Gs/Gd) lineage. The current H5N1 strains in Asia, including the Korean isolates, share a gene constellation similar to that of the Penfold Park, Hong Kong, isolates from late 2002 and contain some molecular markers that seem to have been fixed in the Gs/Gd lineage virus since 2001. However, despite genetic similarities among recent H5N1 isolates, the topology of the phylogenetic tree clearly differentiates the Korean isolates from the Vietnamese and Thai isolates which have been reported to infect humans. A representative Korean isolate was inoculated into mice, with no mortality and no virus being isolated from the brain, although high titers of virus were observed in the lungs. The same isolate, however, caused systemic infections in chickens and quail and killed all of the birds within 2 and 4 days of intranasal inoculation, respectively. This isolate also replicated in multiple organs and tissues of ducks and caused some mortality. However, lower virus titers were observed in all corresponding tissues of ducks than in chicken and quail tissues, and the histological lesions were restricted to the respiratory tract. This study characterizes the molecular and biological properties of the H5N1 HPAI viruses from South Korea and emphasizes the need for comparative analyses of the H5N1 isolates from different countries to help elucidate the risk of a human pandemic from the strains of H5N1 HPAI currently circulating in Asia.

Highly Pathogenic Avian Influenza Virus (H5N1) in Domestic Poultry and Relationship with Migratory Birds, South Korea

During the 2006–2007 winter season in South Korea, several outbreaks of highly pathogenic avian influenza virus (H5N1) were confirmed among domestic poultry and in migratory bird habitats. Phylogenetic analysis showed that all isolates were closely related and that all belong to the A/bar-headed goose/Qinghai/5/2005–like lineage rather than the A/chicken/Korea/ES/2003–like lineage.

Highly pathogenic avian influenza (H5N1) in the commercial domestic ducks of South Korea

The present study reports the clinical, virological and pathological findings observed in a natural outbreak of highly pathogenic avian influenza in farmed commercial ducks. The ducks developed clinical signs, including mild respiratory distress, depression, mild diarrhoea, loss of appetite and increasing mortality (up to 12%). At necropsy, multifocal mottled necrosis was commonly found in the pancreas with splenomegaly, hepatomegaly, and swollen kidneys. Microscopically, there was necrotized pancreatitis and hepatitis, and lymphocytic meningoencephalitis and myocarditis. Influenza viral antigen was demonstrated in areas closely associated with histopathological lesion. Avian influenza virus was isolated from the caecal tonsil, faeces, and kidney of the domestic ducks. The isolated virus was identified as a highly pathogenic H5N1, with a haemagglutinin proteolytic cleavage site deduced amino acid sequence of … QREKRKKR/GLFGAIAG … In order to determine the pathogenicity of the isolate, eight 6-week-old specific pathogen free chickens were inoculated intravenously with the virus, and all birds died within 24u2009h after inoculation. This is the first report of an outbreak of highly pathogenic avian influenza with clinical signs in commercial domestic ducks in South Korea. Influenza Aviaire Hautement Pathogène (H5N1) chez des canards domestiques en Corée du Sud La présente étude rapporte les résultats des observations clinique, virologique et pathologique réalisées à partir dun élevage de canards qui a présenté un cas spontané dinfluenza aviaire hautement pathogène. Les symptômes développés par les canards incluaient une affection respiratoire bénigne, de la dépression, une légère diarrhée, une perte dappétit, et une augmentation de la mortalité (jusquà 12%). A lautopsie, une nécrose marbrée multifocale à généralement été observée au niveau du pancréas avec une splénomégalie, une hépatomégalie et des reins gonflés. Sur le plan microscopique, il a été noté une hépatite et une pancréatite nécrosées, ainsi quune méningo-encéphalite et une myocardite lymphocytaires. Lantigène viral de linfluenza a été mis en évidence dans des zones étroitement associées aux lésions histopathologiques. LAIV a été isolé à partir des amygdales cæcales, des fèces et des reins des canards domestiques. Le virus isolé, a été identifié comme étant H5N1 hautement pathogène, avec la séquence déduite en acides aminés du site de clivage de lhémagglutinine protéolytique : “…u2009QREKRKKR/GLFGAIAGu2009…’. Afin de déterminer la pathogénicité de lisolat, des poulets, exempts de microorganismes pathogènes spécifiés, âgés de 6 semaines ont été inoculés par voie intraveineuse avec le virus et tous les animaux sont morts dans les 24 heures après linoculation. Ceci est le premier rapport dun cas de HPAI avec des signes cliniques chez des canards délevage en Corée du Sud. Hochpathogene aviäre Influenza (H5N1) in kommerziellen Hausenten in Südkorea Die vorliegende Studie berichtet über die klinischen, virologischen und pathologisch-anatomischen Befunde im Rahmen eines natürlichen Ausbruchs einer hochpathogenen Influenza (HPAI) bei kommerziell gehaltenen Enten. Die klinischen Symptome der Enten umfassten geringradige Atemnot, Störung des Allgemeinbefindens, milde Diarrhoe, Appetitlosigkeit und erhöhte Mortalität (bis zu 12%). Bei der pathologisch-anatomischen Untersuchung wurden häufig multifokale, marmorierte Pankreasnekrosen, Spleno- und Hepatomegalie sowie geschwollene Nieren gefunden. Histologisch ließen sich nekrotisierende Pancreatitis und Hepatitis sowie lymphozytäre Meningoenzephalitis und Myocarditis feststellen. Virales Influenza-Antigen wurde in Arealen in Nähe der histopathologischen Läsionen nachgewiesen. AIV wurde aus Zäkaltonsillen, Fäzes und Nieren der Hausenten isoliert. Das isolierte Virus wurde als hochpathogenes H5N1 mit der an der Hämagglutinin-proteolytischen Spaltstelle abgeleiteten Aminosäurensequenz “…u2009QREKRKKR/GLFGAIAGu2009…” identifiziert. Zur Pathogenitätsbestimmung des Isolats wurden acht sechswöchige spezifiziert pathogenfreie Hühnerküken intravenös mit dem Virus inokuliert und alle Tiere starben innerhalb von 24 Stunden. Dies ist die Erstbeschreibung eines Ausbruchs von HPAI mit klinischen Symptomen bei kommerziellen Hausenten in Südkorea. Influenza aviar de alta patogenicidad (H5N1) en patos domésticos comerciales en Corea del Sur En el presente estudio se describen los hallazgos clínicos, virológicos y patológicos asociados a un brote natural de influenza aviar altamente patógena en patos comerciales domésticos. Los patos presentaron distrés respiratorio leve, depresión, leve diarrea, pérdida de apetito y mortalidad incrementada (hasta el 12%). A la necropsia, se observaron áreas multifocales de necrosis en el páncreas, junto con esplenomegalia, hepatomegalia y riñones tumefactos. Al microscopio se observó pancreatitis necrotizante y hepatitis, meningoencefalitis linfocítica y miocarditis. El antígeno vírico de influenza se detectó en áreas muy relacionadas con las lesiones histopatológicas. Se aisló AIV de tonsilas cecales, heces y riñón de los patos domésticos. El virus aislado se identificó como altamente patogéno H5N1, con una secuencia de aminoácidos del punto de ruptura proteolítica de la hemaglutinina de “…QREKRKKR/GLFGAIAG…u2009.’ Para determinar la patogenicidad del aislado, se inocularon vía intravenosa con el aislado, ocho pollos de seis semanas de edad libres de patógenos específicos y todas las aves murieron a las 24 horas tras la inoculación. Esta es la primera descripción de un brote de HPAI con signos clínicos en patos comerciales domésticos en Corea del Sur.

Development of duck hepatitis A virus type 3 vaccine and its use to protect ducklings against infections

A variant type of duck hepatitis A virus (DHAV), DHAV-3 was recently discovered in South Korea and China. Sequence analyses verified that the variant is genetically or serologically different from the DHAV-1 and DHAV-2 types. Duck hepatitis had been reported in South Korea since 1985 and an attenuated DHAV-1 vaccine had efficiently prevented epidemics of DHAV-1 until 2002. Despite the DHAV-1 based vaccine in use the novel DHAV-3 circulating in South Korea remains to be a threat to duckling farming. To develop a live attenuated vaccine against DHAV-3, a representative isolate, AP-04203, was therefore attenuated by repeated passages in SPF chicken embryos 100 times. The 100th passaged virus, AP-04203P100, did not cause clinical sign and mortality in 1-day-old ducklings as well as reversion of virulence capacity. The ducklings vaccinated with AP-04203P100 virus (10(3.0)ELD(50)/0.2ml) on 1-day-old age via the intramuscular injection were well protected from 2 days after challenge with pathogenic AP04203P1 virus via the intramuscular route. In addition, the vaccine candidate also exhibited complete protection against currently circulating pathogenic DHAV-3 isolates. In conclusion, we demonstrate that the live attenuated virus, AP-04203P100, is a promising vaccine candidate facilitating the prevention of duck hepatitis caused by DHAV-3 around East Asia including South Korea.

Characterization of Clade 2.3.2.1 H5N1 Highly Pathogenic Avian Influenza Viruses Isolated from Wild Birds (Mandarin Duck and Eurasian Eagle Owl) in 2010 in Korea

Starting in late November 2010, the H5N1 highly pathogenic avian influenza (HPAI) virus was isolated from many types of wild ducks and raptors and was subsequently isolated from poultry in Korea. We assessed the genetic and pathogenic properties of the HPAI viruses isolated from a fecal sample from a mandarin duck and a dead Eurasian eagle owl, the most affected wild bird species during the 2010/2011 HPAI outbreak in Korea. These viruses have similar genetic backgrounds and exhibited the highest genetic similarity with recent Eurasian clade 2.3.2.1 HPAI viruses. In animal inoculation experiments, regardless of their originating hosts, the two Korean isolates produced highly pathogenic characteristics in chickens, ducks and mice without pre-adaptation. These results raise concerns about veterinary and public health. Surveillance of wild birds could provide a good early warning signal for possible HPAI infection in poultry as well as in humans.

Genetic Comparison of H5N1 Influenza A Viruses Isolated from Chickens in Japan and Korea

Outbreaks of highly pathogenic avian influenza (HPAI) caused by H5N1 virus occurred during 2003 to 2004 in Korea and Japan. The H5N1 viruses isolated in both countries were genetically similar at >99% identity in the nucleotide sequences of all eight RNA segments, indicating that they belong to genotype V and are distinct from HPAI viruses prevalent in southeast Asia that belong to genotype Z. These findings indicate that the H5N1 viruses that caused the HPAI outbreaks in both Korea and Japan were derived from a common ancestor.

H13 influenza viruses in wild birds have undergone genetic and antigenic diversification in nature

Among 16 haemagglutinin (HA) subtypes of avian influenza viruses (AIVs), H13 AIVs have rarely been isolated in wild waterfowl. H13 AIVs cause asymptomatic infection and are maintained mainly in gull and tern populations; however, the recorded antigenic information relating to the viruses has been limited. In this study, 2 H13 AIVs, A/duck/Hokkaido/W345/2012 (H13N2) and A/duck/Hokkaido/WZ68/2012 (H13N2), isolated from the same area in the same year in our surveillance, were genetically and antigenically analyzed with 10 representative H13 strains including a prototype strain, A/gull/Maryland/704/1977 (H13N6). The HA genes of H13 AIVs were phylogenetically divided into 3 groups (I, II, and III). A/duck/Hokkaido/W345/2012 (H13N2) was genetically classified into Group III. This virus was distinct from a prototype strain, A/gull/Maryland/704/1977 (H13N6), and the virus, A/duck/Hokkaido/WZ68/2012 (H13N2), both belonging to Group I. Antigenic analysis indicated that the viruses of Group I were antigenically closely related to those of Group II, but distinct from those of Group III, including A/duck/Hokkaido/W345/2012 (H13N2). In summary, our study indicates that H13 AIVs have undergone antigenic diversification in nature.