Generation and protective efficacy of a cold-adapted attenuated genotype 2b porcine epidemic diarrhea virus

The recent emergence and re-emergence of porcine epidemic diarrhea virus (PEDV) underscore the urgent need for the development of novel, safe, and effective vaccines against the prevailing strain. In this study, we generated a cold-adapted live attenuated vaccine candidate (Aram-P29-CA) by short-term passage of a virulent PEDV isolate at successively lower temperatures in Vero cells. Whole genome sequencing identified 12 amino acid changes in the cold-adapted strain with no insertions and deletions throughout the genome. Animal inoculation experiments confirmed the attenuated phenotype of Aram-P29-CA virus in the natural host. Pregnant sows were orally administered P29-CA live vaccines two doses at 2-week intervals prior to parturition, and the newborn piglets were challenged with the parental virus. The oral homologous prime-boost vaccination of P29-CA significantly improved the survival rate of the piglets and notably mitigated the severity of diarrhea and PEDV fecal shedding after the challenge. Furthermore, strong antibody responses to PEDV were detected in the sera and colostrum of immunized sows and in the sera of their offspring. These results demonstrated that the cold-adapted attenuated virus can be used as a live vaccine in maternal vaccination strategies to provide durable lactogenic immunity and confer passive protection to litters against PEDV.

Evaluation of the efficacy of an attenuated live vaccine based on virulent porcine reproductive and respiratory syndrome virus 2 in young pigs

The efficacy of the CA-2-MP120 vaccine, a cell culture-attenuated strain of virulent porcine reproductive and respiratory syndrome virus (PRRSV), was assessed in pigs. Despite the persistence of viremia in all vaccinated animals during the immunization period, the virus was not detected in vaccinated pigs following challenge. Furthermore, no pigs in the vaccinated group shed PRRSV nasally, orally or rectally throughout the experiment. Moreover, histopathological lung and lymph node lesions in the immunized group were much milder than those in the unimmunized and challenged group. These results indicated that CA-2-MP120 can provide effective protection against virulent wildtype PRRSV-2.

Evaluation of the efficacy of an attenuated live vaccine based on virulent porcine reproductive and respiratory syndrome virus 2 in young pigs / 대한수의학회지

The efficacy of the CA-2-MP120 vaccine, a cell culture-attenuated strain of virulent porcine reproductive and respiratory syndrome virus (PRRSV), was assessed in pigs. Despite the persistence of viremia in all vaccinated animals during the immunization period, the virus was not detected in vaccinated pigs following challenge. Furthermore, no pigs in the vaccinated group shed PRRSV nasally, orally or rectally throughout the experiment. Moreover, histopathological lung and lymph node lesions in the immunized group were much milder than those in the unimmunized and challenged group. These results indicated that CA-2-MP120 can provide effective protection against virulent wildtype PRRSV-2.

Phenotypic and genotypic analyses of an attenuated porcine reproductive and respiratory syndrome virus strain after serial passages in cultured porcine alveolar macrophages

The porcine reproductive and respiratory syndrome virus (PRRSV) is a globally ubiquitous swine viral pathogen that causes major economic losses worldwide. We previously reported an over-attenuated phenotype of cell-adapted PRRSV strain CA-2-P100 in vivo. In the present study, CA-2-P100 was serially propagated in cultured porcine alveolar macrophage (PAM) cells for up to 20 passages to obtain the derivative strain CA-2-MP120. Animal inoculation studies revealed that both CA-2-P100 and CA-2-MP120 had decreased virulence, eliciting weight gains, body temperatures, and histopathologic lesions similar to those in the negative control group. However, compared to CA-2-P100 infection, CA-2-MP120 yielded consistently higher viremia kinetics and enhanced antibody responses in pigs. All pigs inoculated with CA-2-MP120 developed viremia and seroconverted to PRRSV. During 20 passages in PAM cells, CA-2-MP120 acquired 15 amino acid changes that were mostly distributed in nsp2 and minor structural protein-coding regions. Among these changes, 6 mutations represented reversions to the sequences of the reference CA-2 and parental CA-2-P20 strains. These genetic drifts may be hypothetical molecular markers associated with PRRSV macrophage tropism and virulence. Our results indicate that the PAM-passaged CA-2-MP120 strain is a potential candidate for developing a live, attenuated PRRSV vaccine.

Pasteurella multocida isolation from pigs with respiratory disease in Korea

A total of 131 Pasteurella (P.) multocida strains were isolated from the lungs of 1,064 pigs with respiratory clinical signs nationwide during 2009-2010 and 2013-2014. The strains of P. multocida comprised 77.1% serotype A and 22.9% serotype D. Analysis of a recent P. multocida outbreak in Korean pigs showed that the isolation rate of serotype D decreased annually. The incidence of antimicrobial resistance, as measured using minimal inhibitory concentration values, has decreased recently. Overall, further studies to characterize P. multocida isolated from pigs in Korea are needed to prevent P. multocida infection in the Korean swine industry.

Prevalence and Characterization of Actinobacillus pleuropneumoniae Isolated from Korean Pigs

Actinobacillus pleuropneumoniae causes porcine pleuropneumoniae which is one of severe threats to the swine industry. In total, 54 strains of Actinobacillus pleuropneumoniae were isolated from 443 pigs between 2012 and 2013 in Korea. Isolates were classified into serotypes 1, 2, 5, 7, 12, and unclassified by multiplex PCR. Genotypes of isolates were divided into three groups according to the sequence of the omlA gene. The antimicrobial resistance rate of serotype 1 was slightly higher than that of serotype 5. In conclusion, to block and treat porcine pleuropneumonia, it is necessary to conduct ongoing characterization of A. pleuropneumoniae isolated from pigs.

An Outbreak of Food Borne Illness Due to Methomyl Pesticide Intoxication in Korea

On February 21, 2013, 6 elderly people collapsed abruptly after eating bean sprout bibimbab (boiled rice mixed with bean sprouts and seasoned with soybean sauce) at a countryside restaurant in the Chungbuk Province, Korea. Minutes after eating the meal, all of the patients lapsed into a state of stupor. Respiratory arrest developed in 2 patients; and one of two patients died of cardiac arrest. The autopsy identified methomyl and methanol in the deceased patient's gastric contents and in the remaining soybeanbean sauce seasoning. Five of the 6 patients ingested one spoonful of the soybeanbean sauce seasoning and survived, while one patient who died of cardiac arrest, ingested approximately two spoons. Symptoms of toxicity presented quickly in the subjects and progressed rapidly, including chest tightness, an unusual sensation in the pit of the stomach, dizziness, ataxia, and finally, collapse. Three patients who drank ethanol with the meal experienced only mild toxic symptoms. Our analysis of the clinical observations in these cases suggests that ingestion of methomyl pesticide and the additive toxicity of methanol may have been responsible for the intoxication.

Development and evaluation of protective capacity of Salmonella Enteritidis polyphosphate kinase-deleted and temperature-sensitive mutant / 대한수의학회지

This study was focusing on evaluating the protection of polyphosphate kinase (ppk) deleted and/or temperature-sensitive (ts) Salmonella Enteritidis (SE) as an attenuated vaccine in chickens. We constructed SEppk, SEts and SEppk::ts mutants and screened those mutants by growth capability in vitro, protection study in mice model and antibody response in chickens. Among the mutants, SEppk::ts-3 was selected because it showed higher growth capability, good protection against highly virulent SE in mice model, and good antibody response in chickens. SEppk::ts-3 also showed good protection against highly virulent SE isolate because it decreased colonization of virulent SE challenge strain in spleen, liver and cecum compared with the non-vaccinated control. The SEppk::ts-3 mutant showed cross-protection against S. Gallinarum (SG) challenge although the its cross-protection rate was a little lower than that of SG9R, a commercial vaccine against SG infection. To use for live attenuated vaccine in chickens, it should further be characterized.

Protective effects and immunogenicity of Salmonella Enteritidis killed vaccine strains selected from virulent Salmonella Enteritidis isolates / 대한수의학회지

Salmonella Enteritidis (SE) has been a major causative agent of food-borne human disease due to consumption of contaminated eggs and poultry meat. To prevent SE infection in poultry, and therefore minimize human infections, vaccination with either killed or live SE vaccine is suggested. We evaluated a newly developed killed bacterin using a representative SE isolate in Korea. Among pool of SE isolates, two highly virulent isolates (the one isolate from chicken, the other from human) were selected by measuring mortality in mouse and chickens administered. The chickens were injected intramuscularly with killed vaccine and were challenged with highly virulent SE strain 3 week after vaccination. The recovered colony count (cfu/g) of spleen and cecal content in the vaccinated groups was reduced compared with those of the unvaccinated control group. The antibody level in the vaccinated groups was higher at 3 week post vaccination. These results indicate that vaccination with killed vaccine was effective in preventing the infection of virulent SE. Further study for a large number of layers should be needed for the effect of egg production, SE shedding in feces, persistence of antibody level.

A case of Sulfone syndrome hypersensitivity associated with dapsone / 천식및알레르기

Sulfone hypersensitivity syndrome, which is characterized by fever, skin rash, hemolytic anemia, atypical lymphocytosis, and acute hepatic injury, is a potentially fatal variant of dapsone hypersensitivity. A 62-year-old woman with a history of arthralgia developed sulfone syndrome while receiving dapsone 100 mg/day for 20 days. Fever, malaise, prominent rashes, hepatitis, eosinophilia and hemolytic anemia developed and she which required hospitalization. The patient's symptoms reversed following discontinuation of dapsone and administration of steroid (0.5 mg/kg). A case of sulfone syndrome and a brief review of the literature were presented.

Allergic bronchopulmonary aspergillosis with coexistent aspergilloma / 천식및알레르기

A 61-year-old woman with a history of asthma and pulmonary tuberculosis was presented with purulent bloody sputum. She was treated as having lung abscess initially, but her signs and symptoms did not improve with traditional therapy. Finally, in the clinical course and laboratory data during hospitalization, she was diagnosed as ABPA with coexistent aspergilloma. Thereafter she was treated with itraconazole for aspergilloma, and corticosteroid for ABPA. The symptoms of hemoptysis and dyspnea were improved. A case of ABPA with coexistent aspergilloma and a brief review of the literature were presented.

Imported tertian malaria resistant to primaquine

In Plasmodium vivax and Plasmodium ovale malaria, some of the liver stage parasites remain dormant. The activation of these dormant forms (called hypnozoite) can give rise to relapse weeks, months or years after the initial infection. To prevent relapses, a course of primaquine may be given as terminal prophylaxis to patients. Different strains of Plasmodium vivax vary in their sensitivity to primaquine and, recently, cases of relapse of Plasmodium vivax after this standard primaquine therapy were reported from various countries. We reported a case of primaquine resistant malaria which initially was thought to be relapsed caused by loss of terminal prophylaxis.

A Case of Thyrotoxic Periodic Paralysis Presenting as Ventricular Tachycardia / 대한내분비학회지

sociated with hyperthyroidism occurs in 2.0% of Graves disease and is characterized by myasthenia or bilateral flaccid paralysis of lower extremity, in some cases, it may be accompanied with cardiac arrhythmias which are mostly due to hypokalemia. The most common type of cardiac arrhythmias associated with hyperthyroidism is sinus tachycardia, 1015% of patients have atrial fibrillation. Rarely, ventricular tachycardia or ventricular fibrillation develop and lead to cardiac arrest in severe case. A 26-year-old man was admitted to the hospital because of weakness of lower extremity. The initial EKG showed ventricular tachycardia. The laboratory results were, TSH 0.08 microunit/mL, free T4 4.11 ng/mL, T3 2.88 ng/mL, serum K 1.9 mEq/L. He was diagnosed as ventricular tachycardia associated with hypokalemic thyrotoxic periodic paralysis. His symptoms improved during the treatment with propylthiouracil and potassium replacement. We report a case of thyrotoxic periodic paralysis presenting as ventricular tachycardia with brief review of literatures.