An outbreak of avian influenza subtype H9N8 among chickens in South Korea

Kuk Kwon, Yong,Jeong Lee, Youn,Gu Choi, Jun,Kyoung Lee, Eun,Jin Jeon, Woo,Mi Jeong, Ok,Chul Kim, Min,Joon Joh, Seong,Hun Kwon, Jun,Hong Kim, Jae World Veterinary Poultry Association 2006 Avian pathology Vol.35 No.6

<P>Low pathogenic avian influenza subtype H9N8 was diagnosed on a Korean native chicken farm in Gyeonggi province, South Korea, in late April 2004. Clinical signs included moderate respiratory distress, depression, mild diarrhoea, loss of appetite and a slightly elevated mortality (1.4% in 5 days). Pathologically, mucopurulent tracheitis and air sacculitis were prominently found with urate renal deposition. The isolated A/chicken/Kr/164/04 (H9N8) had an Ala-Ser-Gly-Arg (A/S/G/R) motif at the cleavage site of haemagglutinin, which has been commonly found in H9N2 isolated from Korean poultry. Phylogenetic analysis of the haemagglutinin and neuraminidase genes of the H9N8 avian influenza virus (AIV) isolate showed that reassortment had occurred. Its haemagglutinin gene was similar to that of Korean H9N2 AIVs, but its neuraminidase gene was closely related to that of A/WBF/Kr/KCA16/03 (H3N8) isolated from the faeces of wild birds in Korea. The pathogenicity of the isolate was tested on 6-week-old specific pathogen free chickens. The inoculated virus (H9N8) was recovered from most tested organs, including the trachea, lung, kidney, spleen, and caecal tonsil. This is the first report of an outbreak of low pathogenic avian influenza in chickens caused by AIV subtype H9N8.</P><P>Un cas d'influenza aviaire faiblement pathogène (LPAI) de sous type H9N8 a été diagnostiqué dans une ferme de poulets indigènes, dans la province de Gyeonggi, en Corée du Sud, en Avril 2004. Les symptômes consistaient en une détresse respiratoire modérée, une diarrhée peu importante, une perte d'appétit et une mortalité légèrement élevée (1,4% en 5 jours). Sur le plan pathologique, une trachéite mucopurulente et une aérosacculite ont été les lésions les plus souvent observées avec un dépôt d'urate au niveau des reins. La souche isolée A/chicken/Kr/164/04 (H9N8) présentait un motif Ala-Ser-Gly-Arg (A/S/G/R) au niveau du site de clivage de l'hémagglutinine (HA) qui a souvent été observé chez les souches H9N2 isolées de volailles en Corée. L'analyse phylogénétique des gènes de HA et de la neuraminidase (NA) de la souche de virus de l'influenza aviaire (AIV) H9N8 a montré qu'il s'était produit un réassortiment. Son gène HA était similaire à celui des AIVs coréens H9N2, mais son gène NA était très proche de celui de la souche A/WBF/Kr/KCA16/03 (H3N8) isolée de fèces d'oiseaux sauvage en Corée. La pathogénicité de l'isolat a été testée chez des poulets exempts de microorganismes pathogènes spécifiés âgés de 6 semaines. Le virus inoculé (H9N8) a été réisolé de la plupart des organes testés incluant la trachée, les poumons, les reins, la rate et les amygdales cæcales. C'est le premier rapport d'un cas de LPAI chez des poulets causé par un AIV de sous type H9N8.</P><P>Im späten April 2004 wurde auf einer koreanischen Farm mit einheimischen Hühnern in der Gyeonggi-Provinz ein schwach pathogenes aviäres Influenzavirus (LPAI) Subtyp H9N8 isoliert. Die klinischen Symptome umfassten geringe Atembeschwerden, Störung des Allgemeinbefindens, milde Diarrhoe, Appetitlosigkeit und eine geringfügig erhöhte Mortalität (1,4 % in 5 Tagen). Pathologisch-anatomisch wurden als herausragende Veränderungen eine mukopurulente Tracheitis und Aerosacculitis sowie renale Harnsäureablagerungen gefunden. Das Isolat A/chicken/Kr/164/04 (H9N8) besaß ein Ala-Ser-Gly-Arg (A/S/G/R)-Motiv an der Spaltstelle des Hämagglutinins (HA), das auch üblicherweise bei den aus Geflüg

Genotyping of infectious laryngotracheitis virus using allelic variations from multiple genomic regions

Choi, Eun-Jung,La, Tae-Min,Choi, In-Soo,Song, Chang-Seon,Park, Seung-Yong,Lee, Joong-Bok,Lee, Sang-Won World Veterinary Poultry Association 2016 Avian pathology Vol.45 No.4

Analysis of signs and pathology of H5N1-infected ducks from the 2010-2011 Korean highly pathogenic avian influenza outbreak suggests the influence of age and management practices on severity of disease.

Rhyoo, Moon-Young,Lee, Kyung-Hyun,Moon, Oun-Kyung,Park, Woo-Hee,Bae, You-Chan,Jung, Ji-Youl,Yoon, Soon-Seek,Kim, Hye-Ryoung,Lee, Myoung-Heon,Lee, Eun-Joo,Ki, Mi-Ran,Jeong, Kyu-Shik World Veterinary Poultry Association 2015 Avian pathology Vol.44 No.3

<P>We compared the clinical signs, histopathological lesions and distribution of viral antigens among infected young (meat-type) and older (breeder) ducks that were naturally infected with the highly pathogenic avian influenza (HPAI) virus during the 2010-2011 Korean outbreak. The meat-type ducks had a high mortality rate (30%) and showed severe neurological signs such as head tremors and paresis. In contrast, HPAI-infected breeder ducks had minimal clinical signs but a decreased egg production rate. The histopathological characteristics of infected meat-type ducks included necrotic lesions of heart and brain, which may have primarily contributed to the high mortality rate. In contrast, the breeder ducks only presented necrotic splenitis, and viral antigens were only detected in the trachea, lungs and spleen. Younger ducks had a high viral titre in the organs, high levels of viral shedding and a high mortality rate after experimental HPAI virus infection. Compared to the breeder ducks, the meat-type ducks were raised in smaller farms that had poor quarantine and breeding facilities. It is therefore possible that better biosecurity in the breeder farms could have reduced the infection dose and subsequently the severity of the disease. Thus, age and management may be the influencing factors for HPAI susceptibility in ducks.</P>

Generation of a safe Salmonella Gallinarum vaccine candidate that secretes an adjuvant protein with immunogenicity and protective efficacy against fowl typhoid.

Nandre, R M,Lee, J H World Veterinary Poultry Association 2014 Avian pathology Vol.43 No.2

<P>We constructed a live, attenuated Salmonella Gallinarum (SG) that secretes heat-labile enterotoxin B subunit protein (LTB), and evaluated this strain as a new vaccine candidate by assessing its safety, immunogenicity and protective efficacy against fowl typhoid. An asd(+) p15A ori low-copy plasmid containing eltB encoding LTB was transformed into a δlonδcpxRδasd SG (JOL967) to construct the candidate, JOL1355. In Experiments 1 and 2, birds were orally immunized with JOL1355 at 4 weeks of age, while control birds were inoculated with sterile phosphate-buffered saline. In Experiment 2, the birds of both groups were orally challenged with a virulent SG at 8 weeks of age. In Experiment 1, examination for safety revealed that the immunized group did not show any bacterial counts of the vaccine candidate in the liver and spleen. Birds immunized with the vaccine candidate showed a significant increase in systemic IgG and mucosal secretory IgA levels in Experiment 2. In addition, the lymphocyte proliferation response and the numbers of CD3(+)CD4(+) and CD3(+)CD8(+) T cells were also significantly elevated in the immunized group, which indicated that the candidate also induced cellular immune responses. In the protection assay, efficient protection with only 16% mortality in the immunized group was observed against challenge compared with 76% mortality in the control group. These results indicate that the live, attenuated SG secreting LTB can be a safe vaccine candidate. In addition, it can induce humoral and cellular immune responses and can efficiently reduce mortality of birds exposed to fowl typhoid.</P>

Chicken embryo lethality assay for determining the virulence of Riemerella anatipestifer isolates.

Seo, Hye-Suk,Cha, Se-Yeoun,Kang, Min,Jang, Hyung-Kwan World Veterinary Poultry Association 2013 Avian pathology Vol.42 No.4

<P>Riemerella anatipestifer is the causative agent of polyserositis and septicaemia in waterfowl. Twenty-one serotypes have been reported, and there is a strong variation in virulence between strains according to serotype or strain. However, little information is available to assess virulence, such as virulence-associated genes; thus, it is difficult to estimate the risk from field strains. Hence, we established a chicken embryo lethality assay (ELA) model to determine the virulence of R. anatipestifer strains. Three virulent strains (RA T1, RA T7, and V-1) and three avirulent strains (Av-1, Av-2, and Av-3), which were confirmed by duck challenge, were used to perform the ELA. Inoculating 10(2) to 10(4) colony-forming units into the allantoic cavity of 10-day-old embryos discriminated between virulent and avirulent strains based on mortality. Differences in invasion rates into embryonic tissues were found between the RA T1 and Av-1 strains. The maximum colony-forming units of the RA T1 strain were about 1000 times higher than those of the Av-1 strain in the tissue invasion rate for 4 days. We found that the virulent strains killed embryos at mortality rates 50% during the first 3 days after inoculation and that the avirulent strains had death rates of 20% over 5 days. These results obtained by repeated testing suggest that the ELA could be used as a first-line screening method to determine the virulence of R. anatipestifer strains.</P>

Evaluation of the adjuvant effect of Salmonella-based Escherichia coli heat-labile toxin B subunits on the efficacy of a live Salmonella-delivered avian pathogenic Escherichia coli vaccine.

Chaudhari, Atul A,Lee, John Hwa World Veterinary Poultry Association 2013 Avian pathology Vol.42 No.4

<P>The present study evaluated the adjuvant effect of live attenuated salmonella organisms expressing the heat-labile toxin of Escherichia coli B subunit (LTB) on the efficacy of an avian pathogenic Escherichia coli (APEC) vaccine. The Asd(+) (aspartate semialdehyde dehydrogenase) plasmid pMMP906 containing the LTB gene was introduced into a Salmonella enterica Typhimurium strain lacking the lon, cpxR and asd genes to generate the adjuvant strain. Live recombinant Salmonella-delivered APEC vaccine candidates were used for this study. The birds were divided into three groups: group A, non-vaccinated controls; group B, immunized with vaccine candidates only; and group C, immunized with vaccine candidates and the LTB strain. The immune responses were measured and the birds were challenged at 21 days of age with a virulent APEC strain. Group C showed a significant increase in plasma IgG and intestinal IgA levels and a significantly higher lymphocyte proliferation response compared with the other groups. Upon challenge with the virulent APEC strain, group C showed effective protection whereas group B did not. We also attempted to optimize the effective dose of the adjuvant. The birds were immunized with the vaccine candidates together with 110? or 110? colony-forming units of the LTB strain and were subsequently challenged at 3 weeks of age. The 110? colony-forming units of the LTB strain showed a greater adjuvant effect with increased levels of serum IgG, intestinal IgA and a potent lymphocyte proliferation response, and yielded higher protection against challenge. Overall, the LTB strain increased the efficacy of the Salmonella -delivered APEC vaccine, indicating that vaccination for APEC along with the LTB strain appears to increase the efficacy for protection against colibacillosis in broiler chickens.</P>

Characterization of antimicrobial resistance of recent Salmonella enterica serovar Gallinarum isolates from chickens in South Korea.

Kang, Min S,Kim, Aeran,Jung, Byeong Y,Her, Moon,Jeong, Wooseog,Cho, Young M,Oh, Jae Y,Lee, Young J,Kwon, Jun H,Kwon, Yong K World Veterinary Poultry Association 2010 Avian pathology Vol.39 No.3

<P>Salmonella enterica serovar Gallinarum isolates (n=105) from chickens in South Korea between 2002 and 2007 were tested for antimicrobial susceptibility by determining minimum inhibitory concentrations of 16 antimicrobials, and their predominant resistance profiles were genetically characterized. Most isolates (99/105; 94.3%) were resistant to nalidixic acid and resistant/intermediately resistant to fluoroquinolones, and 63.8% (67/105) of the isolates were resistant to three or more antimicrobials. Forty-two quinolone-resistant isolates, of which the quinolone resistance-determining regions of the gyrA genes were sequenced, contained a substitution of a Ser to a Phe or Tyr at position 83 (71.4%), or a substitution of an Asp to an Asn, Gly, or Tyr at position 87 (28.6%). Fifty-seven sulphamethoxazole-resistant isolates were tested for the presence of class 1 integrons by polymerase chain reaction, and their resistance gene cassettes were analysed by sequencing. Three different class 1 integrons containing the resistance-gene insert aadA (52.6%; n=30), aadB (12.3%; n=7), or aadB-aadA (12.3%; n=7) were identified. Most isolates harbouring the integron containing aadB-aadA displayed resistance to all three aminoglycosides tested and also showed increased resistance to fluoroquinolones. These findings suggest that fluoroquinolone resistance may be epidemiologically linked to multiple aminoglycoside resistance.</P>