Experimental infection of a porcine kidney cell line with hepatitis A virus

The hepatitis A virus (HAV) induces severe acute liver injury and is adapted to human and monkey cell lines but not other cells. In this study, the HAV was inoculated into porcine kidney (PK-15) cells to determine its infectivity in porcine cells. The growth pattern of the HAV in PK-15 cells was compared with its growth pattern in fetal rhesus kidney (FRhK-4) cells. The growth of HAV was less efficient in PK-15 cells. In conclusion, HAV replication was verified in PK-15 cells for the first time. Further investigations will be needed to identify the HAV-restrictive mechanisms in PK-15 cells.

Detection and genetic analysis of zoonotic hepatitis E virus, rotavirus, and sapovirus in pigs

The zoonotic transmission of viral diseases to humans is a serious public health concern. Pigs are frequently a major reservoir for several zoonotic viral diseases. Therefore, periodic surveillance is needed to determine the infection rates of zoonotic diseases in domestic pigs. Hepatitis E virus (HEV), rotavirus, sapovirus (SaV), and norovirus (NoV) are potential zoonotic viruses. In this study, 296 fecal samples were collected from weaned piglets and growing pigs in 13 swine farms, and the viral RNA was extracted. Partial viral genomes were amplified by reverse transcription-polymerase chain reaction (PCR) or nested-PCR using virusspecific primer sets under different PCR conditions. HEV-3, rotavirus A, and SaV genogoup 3 were detected from 11.5, 2.7, and 3.0% of the samples, respectively. On the other hand, NoV was not detected in any of the samples. Genetic analysis indicated that the nucleotide sequences of swine HEV-3 and rotavirus A detected in this study were closely related to those of human isolates. However, swine SaV was distant from the human strains. These results suggest that HEV-3 and rotavirus A can be transmitted from pigs to humans. Therefore, strict preventive measures should be implemented by workers in the swine industry to prevent infections with HEV-3 and rotavirus A excreted from pigs.

Evaluation of infertility efficacy of the E. coli expressed STF2-GnRH vaccine in male cats

Gonadotropin-releasing hormone (GnRH) is secreted from the hypothalamus and anti-GnRH antibodies are not formed under normal conditions. However, administration an excess of recombinant GnRH protein results in the formation of anti-GnRH. We evaluated the efficacy of the recombinant Salmonella typhimurium flagellin fljB (STF2)-GnRH vaccine in inducing infertility in 17 intact male cats. The first vaccination and a boosting vaccine was injected for examination. Serum was obtained from blood collected at monthly intervals and anti-GnRH antibodies and testosterone concentrations were determined. Six months after the vaccination, testicular samples are obtained and used for histological examination. Compared with sham control group, the injection groups showed an increase in anti-GnRH antibody titers and testosterone concentrations tended to be reduced in the injection groups and increased in the control group. Histological evaluations and Johnsen's testicular biopsy scores revealed testicular hypoplasia in the 2 injection groups. Consequently, normal sexual maturation with sperm production was observed in the control group. In contrast, the cats that received the GnRH vaccine showed weak (2 of 7 cats) or moderate (4 out of 7 cats) dose-dependent infertility effects. On the basis of the results, the STF2-GnRH vaccine was identified to be effective in inducing infertility in male cats. The results of this study thus indicate the possibility of immunological castration targeting feral cats.

Cytological endometritis in dairy cows: diagnostic threshold, risk factors, and impact on reproductive performance

We determined the threshold proportion of polymorphonuclear leukocytes (PMNs) for a diagnosis of cytological endometritis (CEM), the risk factors for this condition, and its impact on reproductive performance in dairy cows. Uterine cytology was performed on 407 Holstein cows 4 weeks postpartum to determine the proportions of endometrial cells and PMNs. A receiver operator characteristics curve was used to determine the threshold above which the PMN proportion affected the likelihood of cows conceiving by 200 days postpartum. The optimal threshold was ≥ 14% PMN (sensitivity, 31.3%; specificity, 81.7%; p < 0.05). The farm identity, retained placenta (odds ratio [OR] = 1.87), and septicemic metritis (OR = 3.07) were risk factors for CEM (p < 0.05). Cows with CEM were less likely to resume cyclicity (OR = 0.58) and to conceive by 200 days postpartum (hazard ratio = 0.58). Cows with CEM tended (p < 0.1) to be less likely to become pregnant after their first insemination (OR = 0.65) and to require a greater number of inseminations per conception (2.3 vs. 2.2). In conclusion, a PMN threshold of 14% defined the presence of CEM at 4 weeks postpartum. The farm, retained placenta, and septicemic metritis were risk factors for CEM, which reduces subsequent reproductive performance.

Detection of hepatitis E virus genotypes 3 and 4 in pig farms in Korea

Zoonotic transmission of hepatitis E virus (HEV) is mostly mediated by HEV-3 and HEV-4 genotypes, and domestic pigs are an important reservoir of these genotypes. A survey of 14 pig farms in Korea revealed HEV RNA in 30 of 148 (20.3%) fecal samples. HEV-3a and HEV-4c subtypes were identified in five pig farms (35.7%) and two pig farms (14.3%), respectively. Phylogenetic analysis indicated that the isolated HEV strains were closely related to previously reported zoonotic strains in Korea. The results of the genetic analysis partially explain the possible source of the zoonotic transmission of HEV to humans in Korea.

Evaluation of immunocontraceptive vaccine composed of gonadotropin-releasing hormone conjugated with granulocyte-macrophage colony-stimulating factor in male rats

Surgical castration performed to reduce male-associated problems results in pain and microbial infections in male animals. Therefore, immunocontraception, which is mediated by the animal's own antibodies against reproductive hormones, has been recommended as an alternative to surgical castration when considering the animal's welfare. In this study, a new immunocontraceptive vaccine composed of six tandem copies of gonadotropin-releasing hormone (GnRH) fused to rat granulocyte-macrophage colony-stimulating factor (GM-CSF) was developed, and its efficacy was evaluated in male rats. Three different doses (10, 50, and 100 µg) of recombinant GM-CSF–GnRH protein were injected three times at intervals of two weeks into male rats. The rats vaccinated with three doses of GM-CSF–GnRH produced a significantly higher level of antibodies against GnRH than that in the negative control rats. Severe atrophy of gonads was observed in rats vaccinated with three doses of GM-CSF–GnRH but not in the negative control rats. The results reveal that the new GnRH vaccine conjugated with rat GM-CSF induces efficient immunocontraception in male rats. This formulation of the immunocontraceptive vaccine would be applicable to both domestic and pet male animals.

Effects of gonadotropin-releasing hormone administration or a controlled internal drug-releasing insert after timed artificial insemination on pregnancy rates of dairy cows

This study investigated the effects of gonadotrophin-releasing hormone (GnRH) administration (Experiment 1) and a controlled internal drug-releasing (CIDR) insert (Experiment 2) after timed artificial insemination (TAI) on the pregnancy rates of dairy cows. In Experiment 1, 569 dairy cows that underwent TAI (day 0) following short-term synchronization with prostaglandin F(2α) were randomly allocated into two groups: no further treatment (control, n = 307) or injection of 100 µg of gonadorelin on day 5 (GnRH, n = 262). In Experiment 2, 279 dairy cows that underwent TAI (day 0) following Ovsynch were randomly allocated into two groups: no further treatment (control, n = 140) or CIDR insert treatment from days 3.5 to 18 (CIDR, n = 139). The probability of pregnancy following TAI did not differ between the GnRH (34.4%) and control (31.6%, p > 0.05) groups. However, the probability of pregnancy following TAI was higher (odds ratio: 1.74, p < 0.05) in the CIDR group (51.1%) than in the control group (39.3%). Overall, CIDR insert treatment at days 3.5 to 18 increased pregnancy rates relative to non-treated controls, whereas a single GnRH administration on day 5 did not affect the pregnancy outcomes of dairy cows.

Hepatitis E virus as an emerging zoonotic pathogen

Hepatitis E outbreaks are a serious public health concern in developing countries. The disease causes acute infections, primarily in young adults. The mortality rate is approximately 2%; however, it can exceed 20% in pregnant women in some regions in India. The causative agent, hepatitis E virus (HEV), has been isolated from several animal species, including pigs. HEV genotypes 3 and 4 have been isolated from both humans and animals, and are recognized as zoonotic pathogens. Seroprevalence studies in animals and humans indirectly suggest that HEV infections occur worldwide. The virus is primarily transmitted to humans via undercooked animal meats in developed countries. Moreover, transfusion- and transplantation-mediated HEV infections have recently been reported. This review summarizes the general characteristics of hepatitis E, HEV infection status in animals and humans, the zoonotic transmission modes of HEV, and HEV vaccine development status.

Augmented immune responses in pigs immunized with an inactivated porcine reproductive and respiratory syndrome virus containing the deglycosylated glycoprotein 5 under field conditions

PURPOSE: Porcine reproductive and respiratory syndrome virus (PRRSV) leads to major economic losses in the swine industry. Vaccination is the most effective method to control the disease by PRRSV. MATERIALS AND METHODS: In this study, the efficacy of a glycoprotein (GP) 5-modified inactivated vaccine was investigated in pigs. The study was performed in three farms: farm A, which was porcine reproductive and respiratory syndrome (PRRS)-negative, farm B (PRRS-active), which showed clinical signs of PRRS but had not used vaccines, and farm C (PRRS-stable), which had a history of endemic PRRS over the past years, but showed no more clinical signs after periodic administration of modified live virus vaccine. RESULTS: The inactivated vaccine induced great enhancement in serum neutralizing antibody titer, which was sufficient to protect pigs from further infections of PRRSV in a farm where pre-existing virus was circulating. CONCLUSION: These results indicated that vaccination with the inactivated vaccine composed of viruses possessing deglycosylated GP5 would provide enhanced protection to pigs from farms suffering from endemic PRRSV.

Characterization of Lactobacillus reuteri BCLR-42 and Lactobacillus plantarum BCLP-51 as novel dog probiotics with innate immune enhancing properties

Probiotics that are able to provide beneficial effects on animal health have become important ingredients of dog foods. This study was conducted to characterize the probiotic potentials of two strains, Lactobacillus reuteri BCLR-42 and Lactobacillus plantarum BCLP-51, that were derived from feces of healthy dogs and evaluated based on tolerance to low pH and bile acid, antimicrobial activities, enzyme profiles, sensitivity to antibiotics, and innate immune enhancing potentials. Both strains showed survival of more than 90% at pH 3 and 0.2% bile acid and exhibited broad antimicrobial activities against indicator bacteria. Moreover, both strains showed high sensitivity to antibiotics, except vancomycin, metronidazole, and gentamicin. The alkaline phosphatase was negligible (score 0), whereas they showed strong beta galactosidase activity (score range 5 or 3, respectively). The phagocytosis and oxidative burst activities of canine granulocytes were significantly enhanced in response to both strains. These results show that both strains have the capability to act as probiotics and the potential for application as ingredients in dog foods.

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.

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.

Strategic model of national rabies control in Korea

Rabies is an important zoonosis in the public and veterinary healthy arenas. This article provides information on the situation of current rabies outbreak, analyzes the current national rabies control system, reviews the weaknesses of the national rabies control strategy, and identifies an appropriate solution to manage the current situation. Current rabies outbreak was shown to be present from rural areas to urban regions. Moreover, the situation worldwide demonstrates that each nation struggles to prevent or control rabies. Proper application and execution of the rabies control program require the overcoming of existing weaknesses. Bait vaccines and other complex programs are suggested to prevent rabies transmission or infection. Acceleration of the rabies control strategy also requires supplementation of current policy and of public information. In addition, these prevention strategies should be executed over a mid- to long-term period to control rabies.

Development of porcine respiratory and reproductive syndrome virus replicon vector for foot-and-mouth disease vaccine

PURPOSE: Foot-and-mouth disease (FMD) is an economically important global animal disease. To control FMD virus (FMDV) outbreaks, a lot of different novel approaches have been attempted. In this study, we proposed a novel porcine reproductive and respiratory syndrome virus (PRRSV) as a replicon vector to express FMDV structural protein. MATERIALS AND METHODS: PRRSV infectious clone (PRRSVK418DM) was used to develop an expression vector through the reverse genetic manipulation of PRRSV; FMDVP12A3C gene of serotype O was synthesized and used for an antigen. MARC-145 cells (African green monkey kidney epithelial cell line) were used for electroporation mediated transfection. The transfection or the expression of P12A3C and N protein of PRRSV was analyzed by either replicon containing PRRSV alone or by co-infection of helper PRRSV. RESULTS: We constructed PRRSVK418DM replicon vector containing FMDVP12A3C, and genome sequences were confirmed by subsequent sequence analysis. In vitro expression of P12A3C and PRRSV N protein was confirmed by immunofluorescence antibody assay using antibodies specific for PRRSV N protein (anti-PRRSV N MAb), FMDV-VP1 (anti-VP1 MAb). CONCLUSION: The results indicate that PRRSV replicon vector can be a promising novel vector system to control FMDV and useful for vaccine development in the future.

Use of hydrophilic extra-viral domain of canine distemper virus H protein for enzyme-linked immunosorbent assay development

Simple methods for measuring the levels of serum antibody against canine distemper virus (CDV) would assist in the effective vaccination of dogs. To develop an enzyme-linked immunosorbent assay (ELISA) specific for CDV, we expressed hydrophilic extra-viral domain (HEVD) protein of the A75/17-CDV H gene in a pET 28a plasmid-based Escherichia (E.) coli vector system. Expression was confirmed by dot and Western blotting. We proposed that detection of E. coli-expressed H protein might be conformation-dependent because intensities of the reactions observed with these two methods varied. The H gene HEVD protein was further purified and used as an antigen for an ELISA. Samples from dogs with undetectable to high anti-CDV antibody titers were analyzed using this HEVD-specific ELISA and a commercial CDV antibody detection kit (ImmunoComb). Levels of HEVD antigenicity measured with the assays and immunochromatography correlated. These data indicated that the HEDV protein may be used as antigen to develop techniques for detecting antibodies against CDV.

Azidothymidine and recombinant human interferon-alpha therapy in a cat with feline immunodeficiency virus / 동물의과학연구지

A 7-year-old, spayed female, domestic short hair cat showed signs of a 2-week history of chronic anorexia, depression, and severe weight loss. Upon physical examination, pyrexia, mild gingivitis, and pale mucus membranes were noted. Laboratory analysis revealed normocytic normochromic non-regenerative anemia, severe thrombocytopenia, and hypergammaglobulinemia. Serum protein electrophoresis revealed the presence of elevated alpha-2 fraction within the globulin concentration. Based on history, clinical signs, and laboratory results, systemic viral infection was strongly suspected. Reverse transcriptase polymerase chain reaction identified the presence of feline immunodeficiency virus (FIV) in the serum. Furthermore, gene sequencing revealed the virus as FIV subtype A. Treatment with anti-retroviral agents, including azidothymidine (AZT) and recombinant human interferon-alpha, was continued for 4 weeks. However, the patient's clinical condition deteriorated, resulting in death 1 month after initiation of treatment due to progressive renal failure. Necropsy and histopathology revealed hepatic and renal necrosis with hyper-cellular bone marrow mainly comprised of myeloid precursor cells. This case report is the first to describe phylogenetic subtyping, anti-retroviral combination treatment, and clinical outcomes in an FIV-infected cat in Korea. In addition, this report suggests that treatment should be initiated during the early phase of infection that could be effective for the virus.

Induction of antibody and interferon-gamma production in mice immunized with virus-like particles of swine hepatitis E virus

Virus-like particles (VLPs) composed of the truncated capsid protein of swine hepatitis E virus (HEV) were developed and immune responses of mice immunized with the VLPs were evaluated. IgG titers specific for the capsid protein of swine HEV were significantly higher for all groups of mice immunized with the VLPs than those of the negative control mice. Splenocytes from mice immunized with the VLPs also produced significantly greater quantities of interferon (IFN)-gamma than interleukin (IL)-4 and IL-10. These newly developed swine HEV VLPs have the capacity to induce antigen-specific antibody and IFN-gamma production in immunized mice.

Hepatitis E virus infections in humans and animals

Hepatitis E has traditionally been considered an endemic disease of developing countries. It generally spreads through contaminated water. However, seroprevalence studies have shown that hepatitis E virus (HEV) infections are not uncommon in industrialized countries. In addition, the number of autochthonous hepatitis E cases in these countries is increasing. Most HEV infections in developed countries can be traced to the ingestion of contaminated raw or undercooked pork meat or sausages. Several animal species, including pigs, are known reservoirs of HEV that transmit the virus to humans. HEVs are now recognized as an emerging zoonotic agent. In this review, we describe the general characteristics of HEVs isolated from humans and animals, the risk factors for human HEV infection, and the current status of human vaccine development.

Seroprevalence of hepatitis E virus in zoo animal species in Korea / 대한수의학회지

Hepatitis E virus (HEV) can infect not only human but also several animals. This study has been conducted to evaluate the comprehensive anti-HEV seroprevalence in zoo animals in Korea. Anti-HEV antibodies were identified in 14 of 64 zoo animal species. HEV antibodies were detected for the first time in Eurasian Lynx, Setland Pony, Fallow Deer, Ezo Sika, Formosa Deer, East Wapitis, Barasingha, Corriedale, American Bison, Guanacos, Reticulated Giraffe, and Saanen. These results indicate that the several zoo animal species were exposed to HEV.

Epidemiology of Hemorrhagic Fever with Renal Syndrome in Korea, 2001-2010

This study describes the epidemiology of hemorrhagic fever with renal syndrome (HFRS) in the past 10 yr (2001-2010) in Korea. During this period, a total of 3,953 HFRS patients and an average prevalence rate of 0.81 per 100,000 population were recorded, with a total of 40 fatal cases, corresponding to a case fatality rate of 1.01%. More HFRS cases were found in men than in women (57% vs 43%), and a higher prevalence rate of HFRS was observed in patients older than 40 yr (82.1%). The highest numbers of HFRS cases were found amongst farmers (35.6%). The majority of HFRS cases (71.3%) occurred in the last quarter of the calendar year (October to December). More HFRS cases occurred in the western part than in the eastern part of Korea (68.9% vs 31.1%). The incidence of HFRS was significantly higher (P < 0.001) in rural areas than in urban areas (80.3% vs 19.7%). HFRS still occurs commonly among men, in autumn, and in western rural area of Korea.