Immunogenicity of engineered Lactobacillus plantarum expressing porcine epidemic diarrhea virus S1 gene / 生物工程学报

To investigate whether the engineered Lactobacillus plantarum expressing the porcine epidemic diarrhea virus (PEDV) S1 gene can protect animals against PEDV, guinea pigs were fed with recombinant L. plantarum containing plasmid PVE5523-S1, with a dose of 2×10⁸ CFU/piece, three times a day, at 14 days intervals. Guinea pigs fed with wild type L. plantarum and the engineered L. plantarum containing empty plasmid pVE5523 were used as negative controls. For positive control, another group of guinea pigs were injected with live vaccine for porcine epidemic diarrhea and porcine infectious gastroenteritis (HB08+ZJ08) by intramuscular injection, with a dose of 0.2 mL/piece, three times a day, at 14 days intervals. Blood samples were collected from the hearts of the four groups of guinea pigs at 0 d, 7 d, 14 d, 24 d, 31 d, 41 d and 48 d, respectively, and serum samples were isolated for antibody detection and neutralization test analysis by enzyme-linked immunosorbent assay (ELISA). The spleens of guinea pigs were also aseptically collected to perform spleen cells proliferation assay. The results showed that the engineered bacteria could stimulate the production of secretory antibody sIgA and specific neutralizing antibody, and stimulate the increase of IL-4 and IFN-γ, as well as the proliferation of spleen cells. These results indicated that the engineered L. plantarum containing PEDV S1 induced specific immunity toward PEDV in guinea pigs, which laid a foundation for subsequent oral vaccine development.

Immunization against porcine epidemic diarrhea virus and vaccine development / 生物工程学报

Porcine epidemic diarrhea (PED) is a major disease of pigs that inflicts heavy losses on the global pig industry. The etiologic agent is the porcine epidemic diarrhea virus (PEDV), which is assigned to the genus Alphacoronavirus in the family Coronaviridae. This review consists of five parts, the first of which provides a brief introduction to PEDV and its epidemiology. Part two outlines the passive immunity in new born piglets and the important role of colostrum, while the third part summarizes the characteristics of the immune systems of pregnant sows, discusses the concept of the "gut-mammary gland-secretory IgA(sIgA) axis" and the possible underpinning mechanisms, and proposes issues to be addressed when designing a PEDV live vaccine. The final two parts summarizes the advances in the R&D of PEDV vaccines and prospects future perspectives on prevention and control of PEDV, respectively.

Development of a blocking ELISA based on a single-domain antibody target the S1 protein of porcine epidemic diarrhea virus / 生物工程学报

The aim of this study was to develop a blocking enzyme-linked immunosorbent assay (bELISA) based on a biotinylated nanobody target the S1 protein of porcine epidemic diarrhea virus (PEDV) for detecting the anti-PEDV antibodies and evaluating the immune effect of the vaccine. The gene encoding the single-domain antibody sdAb3 target the PEDV S1 protein was amplified and the Avitag sequence was fused at its 3'-end. The PCR product was cloned into the expression vector pET-21b for expression and purification of the sdAb3-Avitag protein. The purified sdAb3-Avitag fusion protein was biotinylated and its activity was determined. Using the recombinant S1 protein as a coating antigen, a bELISA was established and optimized. Serum samples were tested in parallel by the bELISA and a commercial kit. The recombinant vector pET21b-sdAb3-Avitag was constructed to express the tagged sdAb3. After induction for expression, the biotin-labeled sdAb3 (sdAb3-Biotin) with high purity and good activity was obtained. For the optimized bELISA, the coating concentration of the S1 protein was 200 ng/well, the serum dilution was 1:2 and incubated for 2 h, the dilution ratio of the biotinylated sdAb3 was 1:8 000 and incubated for 30 min, the dilution of the enzyme-labeled antibody was 1:5 000 and incubated for 30 min. The bELISA had no cross reaction with the sera of major porcine viruses including transmissible gastroenteritis virus, porcine reproductive and respiratory syndrome virus and showed good specificity and reproducibility. For a total of 54 porcine serum samples tested, the overall compliance rate of the bELISA with a commercial kit was 92.56%. This study developed a rapid and reliable bELISA method, which can be used for serosurveillance and vaccine evaluation for PEDV.

Nota Informativa Infecciones por SARS-CoV-2 en animales: 21 de julio de 2020 / Information Note SARS-CoV-2 Infections in Animals: July 21, 2020

El SARS-CoV-2 es un agente patógeno que causa la enfermedad por COVID-19, la cual fue notificada por primera vez en diciembre de 2019. Se cree que el SARS-CoV-2 fue originado de una fuente animal y posteriormente diseminado a la población humana. A pesar de que se han aislado virus genéticamente relacionados en murciélagos Rhinolophus, no se ha establecido el origen exacto de SARS-CoV-2 y la ruta de introducción de este virus a la población humana sigue siendo objeto de investigación.

Evolution of Avian coronavirus (AvCoV) in BHK-21 and VERO cells / Evolução de Coronavírus aviário (AvCoV) em células BHK-21 e VERO

Avian coronavirus (AvCoV) infects a range of tissues in chickens and several other avian species. Although the virus can be isolated in chicken embryos, only a few strains of the 6 genotypes/33 lineages can grow in cell lines, with the Beaudette strain (GI-1 lineage) being the most used for in vitro studies. Considering the differences between cell lines and chicken embryos as habitats for AvCoV, this study aimed to assess the diversity of the genes coding for the nonstructural protein 3 (nsp3) and spike envelope protein (S) after serial passages in BHK-21 and Vero cells. After 14 passages of an embryo-adapted Beaudette strain, the virus loads fluctuated in both cell lines, with the highest loads being 8.72 log genome copies/µL for Vero and 6.36 log genome copies/µL for BHK-21 cells. No polymorphisms were found for nsp3; regarding S, not only aa substitutions (Vero: 8th passage A150S, and 14th S150A; BHK-21: 4th S53F, 8th F53Y, and 8th S95R), but also minor variants could be detected on chromatograms with fluctuating intensities. As the regions of these aa substitutions are within the receptor-binding domain of S, it can be speculated that differences in cell receptors between Vero and BHK-21 cells and the speed of cell death led to the selection of different dominant strains, while the stability of nsp3 supports its function as a protease involved in AvCoV replication. In conclusion, AvCoV quasispecies evolution is influenced by the biological model under consideration, and a gradual transition is seen for minor and major variants.(AU)

O Coronavírus aviário AvCoV infecta uma variedade de tecidos de galinhas e de outras espécies aviárias. Apesar de este vírus poder ser isolado em ovos embrionados de galinha, apenas alguns dos 6 genótipos / 33 linhagens podem crescer em cultivo celular, sendo a cepa Beuadette (linhagem GI-11) a mais utilizada para estudos in vitro. Considerando as diferentes linhagens celulares e ovos embrionados como habitats para o AvCoV, este estudo teve por objetivo estudar a diversidade de genes que codificam para a proteína não-estrutural 3 (nsp3) e espícula (S) após passagens seriadas em células BHK-21 e VERO. Após 14 passagens, de uma amostra Beuadette adaptada a ovos embrionados, os títulos virais variaram em ambas as células, com os maiores títulos sendo de 8,72 log cópias genômicas/µL para Vero e 6,36 cópias genômicas/µL para BHK-21. Nenhum polimorfismo foi encontrando para nsp3. Considerando a proteína S, não somente foram encontradas substituições de aminoácidos (Vero: 8a passagem A150S e 14a passagem S150A; BHK-21: 4a passagem S53F, 8a passagem F53Y e S95R), mas também, variantes subconsensuais foram detectadas pelos cromatogramas com intensidades flutuantes. Uma vez que as regiões destes aa se encontram no domínio de ligação de receptor de S, pode-se especular que diferenças em receptores celulares entre Vero e BHK-21, além da velocidade da morte celular, levaram à seleção de diferentes cepas dominantes, enquanto que a estabilidade de nsp3 concorda com sua função como protease com papel na replicação de AvCoV. Como conclusão, a evolução de quase-espécies de AvCoV é influenciada pelo modelo biológico sob consideração e uma transição gradual é vista para variantes dominantes e subdominantes.(AU)

Influence of early use of antimicrobial on the health and performance of Holstein calves in the first month of life / Influência do uso precoce de antimicrobiano na sanidade de bezerras holandesas no primeiro mês de vida

The early use of antimicrobial therapy has been introduced in many farms to prevent diarrhea and respiratory disease in young calves; however, there is controversy about whether this practice has a beneficial effect on the health of these animals. This study evaluated the influence of the early use of antimicrobials on the health and performance of neonatal Holstein calves. Twenty-six Holstein calves were screened and divided into two groups, according to the administration (ATB+), or not (ATB-) of tulathromycin (2.5mg/kg, subcutaneously) within the first 12 hours of life. Calves were evaluated by general clinical examination, fecal score, respiratory score, and external palpation of the umbilical region, besides fecal output of dry matter. Anemia was determined by using an automatic system and, also, using a commercial kit for iron dosage. Diarrhea was diagnosed by a centrifuge-flotation technique using a sugar solution (Cryptosporidium) and multiplex semi-nested RT-PCR (rotavirus/coronavirus). The performance of the calves was estimated by Daily Weight Gain (DWG). The young dairy calves were evaluated within 12 hours of birth (≤12h) and at 3-5th (D3-5), 7-9th (D7-9), 13-15th (D13-15), 20-23rd (D20-23), and 27-30th (D27-30) days of life. No difference was noted between the ATB+ and ATB- groups concerning heart rate, respiratory frequency, and rectal temperature. Erythrogram showed a higher frequency of anemia in ATB- group (P=0.016) at the D3-5 check-up; lower values of serum iron were also observed simultaneously (P=0.051). Thirteen cases of respiratory disease were detected during this study; however, no significant difference was observed between the groups in this regard. The frequency of diarrhea (fecal score 2-3) was high in both groups, peaking at D13-D15. No differences were noted between the groups regarding the frequency of diarrhea when considering the dry fecal matter. The predominant etiological agent for diarrhea was Cryptosporidium spp.. The DWG was similar between groups, with maximum weight reduction on D13-15. The administration of tulathromycin in prophylactic dose (2.5mg/kg) at birth decreased the frequency of anemia but did not influence weight gain or the prevalence of diarrhea.(AU)

O uso precoce de antimicrobianos tem sido adotado em muitas fazendas para profilaxia das diarreias e doença respiratória em bezerras, no entanto existem controvérsias sobre os beneficios desta prática na saúde desses animais. Esta pesquisa avaliou a influência do uso precoce de antimicrobiano na sanidade e desempenho de bezerras holandesas recém-nascidas. Para tanto foram selecionadas 26 bezerras Holandesas distribuídas de acordo com a aplicação (ATB+) ou não (ATB-) de tulatromicina (2,5mg/Kg) por via subcutânea até 12h de vida. As bezerras foram examinadas por meio de exame clínico geral, escore fecal, escore respiratório e palpação externa da região umbilical, além da matéria seca fecal. A presença de anemias foi determinada pelo eritrograma utilizando sistema automático e além da dosagem de ferro utilizando kit comercial. O diagnóstico etiológico das diarreias foi investigado por meio da técnica de flutuação em solução saturada de sacarose (Cryptosporidium) e multiplex semi-nested RT-PCR (rotavírus/coronavírus). O desempenho das bezerras foi estimado pelo ganho de peso. As bezerras foram avaliadas até doze horas após o nascimento (≤12h); 3-5º (D3-5); 7-9º (D7-9); 13-15º (D13-15); 20-23º (D20-23); e 27-30º dias de vida (D27-30). Não foram encontradas diferenças entre os grupos ATB+ e ATB- em relação à frequência cardíaca, frequência respiratória e temperatura retal. O eritrograma revelou maior frequência de anemias no grupo ATB- (P=0,016) no D3-5. Neste momento também foram observados menores valores de ferro sérico (P=0,051). Foram detectados treze casos de doença respiratória durante o estudo, no entanto não foi possível detectar diferença entre os grupos. A frequência de diarreias (escore fecal 2 e 3) foi alta em ambos os grupos, observando-se pico no D13-15 (ATB+=92,3%; ATB-=92,3%). Não observamos diferenças entre os grupos em relação a frequência de diarreia considerando-se a matéria seca fecal. O agente etiológico predominante nas diarreias foi o Cryptosporidium. O ganho de peso diário foi igual entre grupos, com intensa redução no GPD no D13-15. A administração de tulatromicina na dose profilática (2,5mg/Kg) ao nascimento diminuiu a frequência de anemias e não influenciou no ganho de peso e prevalência de diarreias.(AU)

Seroepidemiological study of feline coronavirus (FCoV) infection in domiciled cats from Botucatu, São Paulo, Brazil / Estudo soroepidemiológico da infecção pelo coronavírus felino (FCOV) em gatos domiciliados de Botucatu, São Paulo, Brasil

Feline coronavirus (FCoV) is responsible for causing one of the most important infectious diseases of domestic and wild felids, the feline infectious peritonitis (FIP), which is an immune-mediated, systemic, progressive and fatal disease. FCoV is highly contagious, and infection is common in domestic feline populations worldwide. The present study aimed to determine the seropositivity of FCoV infection and its associated epidemiological variables (risk factors) in domiciled cats in Botucatu, São Paulo, Brazil. Whole blood samples (0.5-1mL) were collected from 151 cats, and sera were extracted by centrifugation. These sera were tested by an commercial enzyme-linked immunosorbent assay (ELISA) for the detection of IgG anti-FCoV antibodies. The assessed risk factors were age range, breed, gender, reproductive status, outdoor access and rearing mode (living alone or in a group). The seropositivity was 64.2% (97/151). There was no statistical significance for risk factors related to breed, gender or rearing mode. There were significant differences in seropositivity (p-values ≤0.05) for age range (p=0.0157), reproductive status (p=0.0074) and outdoor access (p=0.0001). This study verified a wide dissemination of FCoV in the studied population, with a higher than expected seropositivity for indoor cats. Among the risk factors, age range, reproductive status and outdoor access presented statistically significant differences, thus helping to establish an epidemiological profile of this population.(AU)

O coronavírus felino (FCoV) é responsável por causar uma das mais importantes doenças infecciosas que acometem os felinos domésticos e selvagens, a peritonite infecciosa felina (PIF), que é uma enfermidade imunomediada, sistêmica, progressiva e fatal. O FCoV é altamente contagioso e a infecção é comum nas populações de felinos domésticos por todo o mundo. O presente estudo objetivou determinar a soropositividade da infecção pelo FCoV e correlacionar variáveis epidemiológicas (fatores de risco) de gatos domiciliados de Botucatu, São Paulo, Brasil. Amostras de sangue total (0,5 a 1mL) foram colhidas de 151 gatos e os soros foram obtidos após centrifugação. Estes soros foram testados por um teste commercial de ELISA para detecção de anticorpos IgG anti-FCoV. Os fatores de risco avaliados foram faixa etária, raça, gênero, condição reprodutiva, acesso à rua e modo de criação (viver solitário ou em grupo). Observou-se uma soropositividade de 64,2% (97/151). Não houve significância estatística para os fatores de risco relacionados à raça, gênero e modo de criação. Houve significância estatística quanto a soropositividade (p-values ≤0,05) para os fatores de risco faixa etária (p=0,0157), condição reprodutiva (p=0,0074) e acesso à rua (p=0,0001). Através do presente estudo verificou-se que o FCoV está amplamente disseminado na população estudada, onde a soropositividade encontrada foi maior do que a esperada para gatos domiciliados. Dentre os fatores de risco, faixa etária, condição reprodutiva e acesso à rua apresentaram diferenças estatisticamente significativas, contribuindo assim, para se estabelecer um perfil epidemiológico desta população.(AU)

Passive immunity to control Bovine coronavirus diarrhea in a dairy herd in Argentina / Inmunidad pasiva en el control de la diarrea por coronavirus bovino en un rodeo lechero de Argentina

Bovine coronavirus (BCoV) is a viral enteric pathogen associated with calf diarrhea worldwide being, in Argentina, mostly detected in dairy husbandry systems. The aim of the present work was to study if maternal IgG1 antibodies (Abs) to BCoV acquired by colostrum intake modulate the development of BCoV infection in calves reared in a dairy farm in Argentina. Thirty Holstein calves were monitored during their first 60 days of age. Animals were classified into two groups depending on their initial BCoV IgG1 Ab titers. The "failure of passive transfer" (FPT) group had significantly lower IgG1 Abs to BCoV than the "acceptable passive transfer" (APT) group of calves (log10 1.98 vs. 3.38 respectively) (p<0.0001). These differences were also observed when the total protein levels in both groups were compared (p = 0.0081). Moreover, 71% (5/7) of calves from the FPT group showed IgG1 seroconversion to BCoV compared to 29.4% (5/17) of animals from the APT group. Regarding viral circulation, BCoV was detected in 10% (3/30) of all calves and BCoV IgG1 Ab seroconversion was detected in 42% of the total animals showing that almost half of the calves were infected with BCoV. In conclusion, calves with high titers of specific BCoV IgG1 (≥1024) were mostly protected against viral infection, while animals with low titers of IgG1 (<1024) were mostly infected with BCoV. IgG1 Abs from colostrum origin are critical for prevention of BCoV infection.

El coronavirus bovino (Bovine coronavirus, BCoV) es un enteropatógeno viral asociado a la diarrea neonatal del ternero. El objetivo del presente trabajo fue estudiar si los anticuerpos IgG1 anti-BCoV adquiridos pasivamente mediante el calostro modulan la infección por BCoV en terneros de un rodeo lechero de Argentina. Se monitorearon 30 terneros raza Holstein durante los primeros 60 días de vida. Estos animales fueron clasificados en dos grupos según sus niveles de IgG1 anti-BCoV maternales: grupo con transferencia de inmunidad pasiva aceptable (APT) y grupo con fallas en la transferencia pasiva (FPT). Este último grupo tenía un título de IgG1 significativamente menor comparado con el primer grupo (log10 1,98 vs. 3,38, respectivamente; p< 0,0001). La misma diferencia se observó cuando se compararon los niveles de proteínas séricas totales (p = 0,0081). Además, el 71% (5/7) de los terneros del grupo FPT mostró seroconversión de IgG1, mientras que el 29,4% (5/17) de los terneros del grupo APT la mostró. Con respecto a la circulación viral, se detectó BCoV en el 10% (3/30) de los terneros así como también seroconversión de IgG1 en el 42% del total de los animales, lo que evidencia que aproximadamente la mitad de los terneros se infectaron con BCoV. Este estudio mostró que los terneros con altos títulos de IgG1 específica (≥ 1.024) estuvieron mayormente protegidos contra la infección con BCoV, mientras que los animales con títulos bajos de IgG1 (< 1.024) estuvieron predispuestos a la infección. Esto confirma que los anticuerpos IgG1 calostrales son críticos para la prevención de la infección por este agente viral.

A simple and rapid identification method for newly emerged porcine Deltacoronavirus with loop-mediated isothermal amplification

BACKGROUND: Porcine Deltacoronavirus (PDCoV) is a newly emerged enteropathogenic coronavirus that causes diarrhea and mortality in neonatal piglets. PDCoV has spread to many countries around the world, leading to significant economic losses in the pork industry. Therefore, a rapid and sensitive method for detection of PDCoV in clinical samples is urgently needed. RESULTS: In this study, we developed a single-tube one-step reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay specific for nucleocapsid gene to diagnose and monitor PDCoV infections. The detection limit of RT-LAMP assay was 1 × 101 copies of PDCoV, which was approximately 100-fold more sensitive than gel-based one-step reverse transcription polymerase chain reaction (RT-PCR). This assay could specifically amplify PDCoV and had no cross amplification with porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), porcine kobuvirus (PKoV), porcine astrovirus (PAstV), porcine reproductive and respiratory syndrome virus (PRRSV), classic swine fever virus (CSFV), and porcine circovirus type 2 (PCV2). By screening a panel of clinical specimens (N = 192), this method presented a similar sensitivity with nested RT-PCR and was 1-2 log more sensitive than conventional RT-PCR in detection of PDCoV. CONCLUSIONS: The RT-LAMP assay established in this study is a potentially valuable tool, especially in low-resource laboratories and filed settings, for a rapid diagnosis, surveillance, and molecular epidemiology investigation of PDCoV infections. To the best of our knowledge, this is the first work for detection of newly emerged PDCoV with LAMP technology.

Occurrence of ferret enteric coronavirus in Brazil (Preliminary Report) / Ocorrência de coronavírus entérico de ferrets no Brasil - Nota Prévia

Ferret enteric coronavirus (FECV) is associated to the epizootic catarrhal enteritis (ECE) in ferrets (Mustela putorius furo). In this study, we report the occurrence of this agent in four diarrheic stool samples of domestic ferrets, analyzed by negative staining transmission electron microscopy and a specific RT-PCR assay targeting the nucleocapsid (N) gene. These findings are the first report of FECV in Brazil and address the importance of this virus on the etiology of enteric disorders in ferrets.

Coronavírus entérico de furões (FECV) é associado à enterite catarral epizoótica (ECE) em furões (Mustela putorius furo). Neste estudo, relatamos a ocorrência deste agente em quatro amostras fecais diarreicas de furões domésticos, analisadas por microscopia eletrônica de transmissão (contrastação negativa) e RT-PCR específica e direcionada ao gene de nucleocapsídeo (N). Estes achados constituem o primeiro relato de FECV no Brasil e remetem para a importância deste vírus na etiologia de quadros entéricos nestes animais.

Detection and molecular characterization of infectious bronchitis virus isolated from recent outbreaks in broiler flocks in Thailand

Thirteen field isolates of infectious bronchitis virus (IBV) were isolated from broiler flocks in Thailand between January and June 2008. The 878-bp of the S1 gene covering a hypervariable region was amplified and sequenced. Phylogenetic analysis based on that region revealed that these viruses were separated into two groups (I and II). IBV isolates in group I were not related to other IBV strains published in the GenBank database. Group 1 nucleotide sequence identities were less than 85% and amino acid sequence identities less than 84% in common with IBVs published in the GenBank database. This group likely represents the strains indigenous to Thailand. The isolates in group II showed a close relationship with Chinese IBVs. They had nucleotide sequence identities of 97-98% and amino acid sequence identities 96-98% in common with Chinese IBVs (strain A2, SH and QXIBV). This finding indicated that the recent Thai IBVs evolved separately and at least two groups of viruses are circulating in Thailand.

Molecular analysis of the bovine coronavirus S1 gene by direct sequencing of diarrheic fecal specimens

Bovine coronavirus (BCoV) causes severe diarrhea in newborn calves, is associated with winter dysentery in adult cattle and respiratory infections in calves and feedlot cattle. The BCoV S protein plays a fundamental role in viral attachment and entry into the host cell, and is cleaved into two subunits termed S1 (amino terminal) and S2 (carboxy terminal). The present study describes a strategy for the sequencing of the BCoV S1 gene directly from fecal diarrheic specimens that were previously identified as BCoV positive by RT-PCR assay for N gene detection. A consensus sequence of 2681 nucleotides was obtained through direct sequencing of seven overlapping PCR fragments of the S gene. The samples did not undergo cell culture passage prior to PCR amplification and sequencing. The structural analysis was based on the genomic differences between Brazilian strains and other known BCoV from different geographical regions. The phylogenetic analysis of the entire S1 gene showed that the BCoV Brazilian strains were more distant from the Mebus strain (97.8 percent identity for nucleotides and 96.8 percent identity for amino acids) and more similar to the BCoV-ENT strain (98.7 percent for nucleotides and 98.7 percent for amino acids). Based on the phylogenetic analysis of the hypervariable region of the S1 subunit, these strains clustered with the American (BCoV-ENT, 182NS) and Canadian (BCQ20, BCQ2070, BCQ9, BCQ571, BCQ1523) calf diarrhea and the Canadian winter dysentery (BCQ7373, BCQ2590) strains, but clustered on a separate branch of the Korean and respiratory BCoV strains. The BCoV strains of the present study were not clustered in the same branch of previously published Brazilian strains (AY606193, AY606194). These data agree with the genealogical construction and suggest that at least two different BCoV strains are circulating in Brazil.

Sequence analysis of the S1 glycoprotein gene of infectious bronchitis viruses: identification of a novel phylogenetic group in Korea

Twelve Korean infectious bronchitis viruses (IBVs) were isolated in the field from chickens suspected of being carriers of infectious bronchitis between 2001 and 2003. The S1 glycoprotein genes of these IBV isolates were amplified by reverse transcriptase-polymerase chain reaction (RTPCR) and analyzed by restriction fragment length polymorphism (RFLP) analysis. These Korean IBV isolates were classified into three groups according to their RFLP patterns obtained using the restriction enzyme HaeIII. Half of the twelve isolates were similar to the KM91 RFLP pattern, which is a common pattern in Korea. Three more isolates were related to the Arkansas strain pattern, but with some unique variations. The other three viruses showed variant RFLP patterns. For a comparison with the published sequences for non-Korean IBV strains, amplified PCR products from the twelve isolates were cloned and sequenced. The Korean IBV field isolates had 71.2-99.7% nucleotide sequence homology with each other and 45.9-80.7% nucleotide sequence homology with non-Korean IBV strains. With respect to the deduced amino acid sequence, the Korean IBV isolates had 71.5-99.3% similarity with each other and 44.9-80.3% similarity with non-Korean IBV strains. Phylogenetic tree analysis revealed that some of the IBV isolates appear to belong to a new group, different from the non-Korean IBV strains or from previously isolated Korean IBV strains. Specifically, the new Korean IBV isolates K10217-03, K3-3 and K1255-03 represented a separate group. These findings suggest that the Korean IBVs appear to be continuously evolving.

Identification of a putative cellular receptor 150 kDa polypeptide for porcine epidemic diarrhea virus in porcine enterocytes

Porcine epidemic diarrhea virus (PEDV) causes an acute enteritis in pigs of all ages, often fatality for neonates. PEDV occupies an intermediate position between two well characterized members of the coronavirus group I, human coronavirus (HCoV-229E)and transmissible gastroenteritis virus (TGEV) which uses aminopeptidase N (APN), a 150 kDa protein, as their receptors. However, the receptor of the PEDV has not been identified yet. A virus overlay protein binding assay (VOPBA) was used to identify PEDV binding protein in permissive cells. The binding ability of PEDV to porcine APN (pAPN) and the effects of pAPN on infectivity of PEDV in Vero cells were also investigated. VOPBA identified a 150 kDa protein, as a putative PEDV receptor in enterocytes and swine testicle (ST) cells. Further the PEDV binding to pAPN was blocked by anti-pAPN and pAPN enhanced PEDV infectivity in Vero cells. In conclusion, these results suggested that pAPN may act as a receptor of PEDV.