• Journal of Veterinary Science
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• 제19권6호
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• pp.759-770
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• 2018

Fowl adenovirus (FAdV) is distributed worldwide and causes economic losses in the poultry industry. The objectives of this study were to determine the hexon and fiber gene changes in an attenuated FAdV isolate from Malaysia in specific pathogen-free chicken embryonated eggs (SPF CEE) and its infectivity in commercial broiler chickens. SPF CEE were inoculated with 0.1 mL FAdV inoculum via the chorioallantoic membrane (CAM) for 20 consecutive passages. The isolate at passage 20 (E20), with a virus titer of $10^{8.7}TCID_{50}/mL$ ($TCID_{50}$, 50% tissue culture infective dose), was inoculated (0.5 mL) into one-day-old commercial broiler chicks either via oral or intraperitoneal routes. The study demonstrated that 100% embryonic mortality was recorded from E2 to E20 with a delayed pattern at E17 onwards. The lesions were confined to the liver and CAM. Substitutions of amino acids in the L1 loop of hexon at positions 49 and 66, and in the knob of fiber at positions 318 and 322 were recorded in the E20 isolate. The isolate belongs to serotype 8b and is non-pathogenic to broiler chickens, but it is able to induce a FAdV antibody titer. It appears that molecular changes in the L1 loop of hexon and the knob of fiber are markers for FAdV infectivity.

• Fisheries and Aquatic Sciences
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• 제25권6호
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• pp.320-326
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• 2022

Most of the emerging diseases that threaten humans are caused by RNA viruses which are extremely mutable during evolution. The fish RNA virus, viral hemorrhagic septicemia virus (VHSV) can infect a broad range of aquatic animal hosts, but the transmissibility of VHSV to mammals has not been thoroughly investigated. Therefore, our study aimed to investigate the potential adverse effects of VHSV in mammals. Briefly, the survival of VHSV was determined using only minimum essential media (MEM-2) and mammalian SNU-1411 and hepa-1c1c7s cells at 15℃ and 37℃. Mice (Mus musculus, 27.3 ± 1.9 g) were intravenously injected with VHSV (2.37E+05 TCID₅₀·mice^-1) in triplicate. Clinical signs and survival rates were examined at 14 days post-challenge, and infection was confirmed in the surviving mice. The 50% tissue culture infective dose (TCID₅₀) and polymerase chain reaction analysis were used to determine viral titers and the infection rate, respectively. The titer of VHSV suspended in MEM-2 at 15℃ was reduced by only one log after 8 days, whereas the virus maintained at 37℃ was inactivated 8 days post-inoculation (dpi). There were no recognizable cytopathic effects in either SNU-1411 or hepa-1c1c7s cells inoculated with VHSV at 15℃ and 37℃. VHSV in those cell lines at 37℃ was rapidly decreased and eventually inactivated at 12 dpi, whereas virus at 15℃ remained at low concentrations without replication. In vivo experiment showed that there were no signs of disease, mortality, or infection in VHSV-infected mice. The results of this study indicate that it is highly unlikely that VHSV can infect mammals including humans.

• 한국어병학회지
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• 제28권2호
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• pp.113-116
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• 2015

A $0.45-{\mu}m$ membrane filter is generally used to remove bacterial contamination during virus extraction from fish samples. However, the number of fish viruses is drastically reduced after filtration with a $0.45{\mu}m$ filter. In this study, we investigated the effect of filters on virus infectivity titer and the change in virus titer and bacterial number following different centrifugation conditions to determine a suitable procedure for virus extraction from fish samples. $10^{4.05}$ and $10^{5.05}TCID_{50}/ml$ of infectious hematopoietic necrosis virus (IHNV) and $10^{4.05}$ and $10^{4.55}TCID_{50}/ml$ of Oncorhynchus masou virus (OMV) were not detectable after filtration with two types of $0.45-{\mu}m$ filters, except the IHNV titer was reduced by about 10 fold after filter use (company A). No significant difference was found in the virus titer following centrifugation at $880{\times}g$ (30 min) or $3,500{\times}g$ (30 min), whereas IHNV and OMV titers were reduced by about 10 and 10-1000 fold by centrifugation at $14,000{\times}g$ (30 min) and $14,000{\times}g$ (10 and 30 min), respectively. A total of 97.7-99.9% Escherichia coli were eliminated by centrifugation at $880 {\times}g$ (30 min) and $3,500{\times}g$ (30 min). These results show that fish viruses were affected by filtering, even though the effect differed by virus species and filter type. Therefore, centrifugation at $3,500{\times}g$ (30 min) and use of medium with antibiotics may be useful for virus extraction along with a reduction in bacteria.

• 한국동물위생학회지
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• 제14권2호
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• pp.110-120
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• 1991

28 porcine enteroviruses were isolated from 86 pig-feces of 9 swine farms located in south region, Chung-buk, from March to September 1990. Physico-chemical properties and pathogenicity of isolates were investigated. Results obtained throughout experiments are summarized as follows. According to the age, weanlings(40-90 days), sucklings(10-30 days) and adult pigs(6 months over) showed the isolation rate of 67%. 8% and 4%, respectively. By physico-chemical tests, YD-90/22, YD-90/43 and YD-90/64 strains were found to be ether, chloroform and PH stable. Nucleic acid test suggests the virus to have a DNA genome. Most of the Isolates were not evident of hemagglutinin using erythrocytes from various mammalian & avian. 22 strains among the isolates were shown CPE type I and the remainders were CPE type II. 3 strains among isolates of CPE type I strains were neutralized with high titers to serotype 2 antiserum. In the study on virus growth curve in PK-l5 cells, YD-90/22, YD-90/43 and YD-90/64 strains showed the maximum infectivity titers($10^{6.0}-l0^{6.5} TCID({50}ml$) at 4days post inoculation(PI). When 30 day-old commercial piglets were inoculated only intraoral route with the YD-90/22 strain at $10^{6.0} TCID_{50}ml,$ piglets not showed the symptoms. But piglets inoculated by intramuscle route, intraoral and intramuscle route after pretreat with dexamethasone(2.5mg /kg) for 5 days were shown the symptoms of anorexia, diarrhea, pyrexia and ataxia at 4th-6th days PI. The viral reisolation in the virus-inoculated piglets was examined from feces. The viruses were recovered intermittently from 2nd to 16th day PI and at 4th-6th day PI, all piglets excreted viruses.

• 한국어병학회지
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• 제33권1호
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• pp.63-69
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• 2020

Fish culture is constantly threatened by various infectious diseases which are largely transmitted by water. Plasma technology is being used to sterilize polluted water in many industries. In this study, two bacterial pathogens Aeromonas salmonicida and Streptococcus iniae, and a virus (viral hemorrhagic septicemia virus, VHSV) were subjected to plasma water that was produced by a corona discharge system. Growth of A. salmonicida was greatly inhibited from 10^5.61 CFU/ml in positive control to 10^3.51 CFU/ml in treated group by only 60 sec contact with plasma water. Similarly, S. iniae was inhibited from 10^5.85 CFU/ml to 10^3.40 CFU/ml. VHSV titer also decreased from 10^4.1 TCID₅₀/ml to 10^1.45 TCID₅₀/ml by the same treatment. Activation of water by the plasma was confirmed by the existence of ozone in the plasma water. These results suggest that plasma water could efficiently disinfect fish pathogens, possibly by the action of reactive oxygen species contained in the plasma water.

• Journal of Microbiology and Biotechnology
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• 제10권5호
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• pp.728-732
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• 2000

Propagation of Anagrapha falcifera nuclear polyhedrosis virus(AfNPV) was investigated using well-plates and split-flow air-lift bioreactors. In well-plate experiments, the effects of pH, cell density at a point of infection, serum concentration, DEAE-dextran, and lipid on virus propagation were all closely examined. The AfNPV titer in well-plates was optimal at pH 6.8 and $3{\times}10^6$ cells/$cm^2$. The virus titer was not dramatically affected when the fetal bovine serum concentration was reduced from 10% to 5%. The addition of cholesterol at AfNPV infection of Sf21 cells enhanced the virus titer, whereas the addition of DEAE-dextran did not improve the titer. The AfNPV titer ($3.8{\times}10^7$ $TCID_{50}/ml$) at optimized conditions for well-plate experiments was 2.5-fold higher than for the control. In bioreactor experiments, the AfNPV titer showed its maximum level at air flow rates of 20-40 ml/min. In a split-flow air-lift bioreactor, AfNPV titer ($2.3{\times}10^7\;TCID_{50}/ml$) was 1.5-fold higher than the control when the culture was at pH 6.8 and supplemented with 0.34 mM cholesterol.

• 한국어병학회지
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• 제13권1호
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• pp.53-59
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• 2000

우리나라 연안의 9곳의 지역에 위치한 넙치종묘생산장의 성숙 친어 및 친어용 자연채집어를 대상으로 각각의 생식소를 채집하여 체내 MABV 감염상황을 PCR법을 이용하여 검색한 결과 검사어의 34%가 MABV 감염 양성반응을 나타내었다. PCR 반응양성 어류의 샘플로부터 CHSE-214 세포주를 이용한 바이러스의 배양을 행한 결과, 친어 체내 생식소에 있어 바이러스 감염가가 $10^{2.30}$에서 $10^{4.30}$ $TCID_{50}$/g(ml)의 titer를 보여, 정상적인 친어로 보이는 개체내의 바이러스 잠복감염이 인정되었다. 각각의 다른 어체로부티 분리되어진 바이러스는 중화반응에 따른 검토결과 동일종의 MABV임을 확인할 수 있었다. 종묘생산용으로 관리중인 넙치 친어로 부터 MABV의 잠복감염 확인으로 친어를 매개로한 감염의 가능성이 확인되어졌다.

• 한국어병학회지
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• 제13권1호
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• pp.61-66
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• 2000

해수중에 소수로 분포하는 어류 병원 바이러스의 검출을 목적으로 해산어류 병원바이러스의 일종인 marine birnavirus (MABV)를 대상으로하여 한외 여과막과 centricon을 이용한 농축효과를 바이러스의 주화세포내 감염에 의해 형성되어지는 CPE (cytopathic effect) 출현에 근거한 바이러스 감염가 측정법인 $TCID_{50}$ 계수법 및 주화세포상의 바이러스 감염에 의해 형성되어지는 plaque 계수법을 통해 검토하였다. 바이러스 희석액 시료 20 L를 1차 중공사한외여과막으로 3 시간 가동하면 200배로 농축되어지고, centricon으로 2차 농축하여 최초 시료 대비 20,000배 (최종량: 1 ml)로 농축가능하였다. 바이러스 회수율은 농축 전 바이러스 감염가와 비교하여 $TCID_{50}$치로서는 94.4%, plaque 계수법으로는 88.7%를 나타내었다. 중공사 한외여과막과 centricon을 이용한 본 농축법은 해수내 바이러스의 검출을 위한 효과적인 농축방법으로 수계 바이러스 연구에 이용되어질 수 있을 것으로 판단되어졌다.

• 대한수의학회지
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• 제34권2호
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• pp.321-326
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• 1994

돼지 유행성 설사 바이러스(KPEDV-9)주를 이용하여 세포내 증식성을 비롯한 혈청학적 역학조사를 수행하였던 바 다음의 결과를 얻었다. 돼지 유행성 설사바이러스 국내 분리주는 Vero 세포에 연속계대시 증식성이 증가되었으며 90대 계대시 $10^{5.5}TCID_{50}/ml$의 역가를 나타내었다. 조직배양 순화주를 이용하여 간염세포내에서 20Kb 이상의 RNA가 존재함을 확인할수 있었으며 전자현미경 검사시 5~10nm의 외피항원 및 80~300nm크기의 coronavirus특징을 나타내었다. 설사증상을 나타내는 돼지의 장가검재료를 이용하여 유행성 설사 바이러스의 감염실태를 조사하였던 바 18%에 상당하는 감염 양성율을 확인하였으며 ELISA법에 의한 항체검사결과 전국적으로 약 45%의 항체 양성율을 나타내었다.

• 한국어병학회지
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• 제34권1호
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• pp.99-104
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• 2021

In this study, we investigated safety and efficacy of a low temperature immunization protocol with NNV in red spotted grouper, Epinephelus akaara and long tooth grouper, Epinephelus bruneus and seven band grouper, Hyporthodus septemfasciatus. Further, growth rate between immunized and naïve fish was evaluated during the experiment to check side effect of immunization. Three grouper species were immunized by immersion method with live NNV at 10^5.0 TCID₅₀/mL at 16.5℃ for 30 min and reared for 120 days at natural sea water temperature. To evaluate growth rate, total length and wet weight was measured 7 times after immunization. Immunized three grouper species were challenged by intramuscular inoculation with NNV at 10^4.2 TCID₅₀/100 µL/fish. Immunization at low temperature with live NNV did not show any clinical symptoms of infection, mortality and inhibition of growth. After challenge, cumulative mortality of naïve seven band grouper, red spotted grouper, long tooth grouper were 45, 10, 20 %, respectively. However no mortality was observed at immunized groupers. Thus, it was demonstrated that immunization at low temperature with live NNV are able to protect three different species of groupers without inhibition of growth.