• 한국동물위생학회지
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• 제46권2호
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• pp.123-135
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• 2023

Feline calicivirus (FCV) is considered the main viral pathogen of feline upper respiratory tract disease (URTD). The frequent mutations of field FCV strains result in the poor diagnostic sensitivity of previously developed molecular diagnostic assays. In this study, a more sensitive real-time reverse transcription-polymerase chain reaction (qRT-PCR) assay was developed for broad detection of currently circulating FCVs and comparatively evaluated the diagnostic performance with previously developed qRT-PCR assay using clinical samples collected from Korean cat populations. The developed qRT-PCR assay specifically amplified the FCV p30 gene with a detection limit of below 10 copies/reaction. The assay showed high repeatability and reproducibility, with coefficients of intra-assay and inter-assay variation of less than 2%. Based on the clinical evaluation using 94 clinical samples obtained from URTD-suspected cats, the detection rate of FCV by the developed qRT-PCR assay was 47.9%, which was higher than that of the previous qRT-PCR assay (43.6%). The prevalence of FCV determined by the new qRT-PCR assay in this study was much higher than those of previous Korean studies determined by conventional RT-PCR assays. Due to the high sensitivity, specificity, and accuracy, the new qRT-PCR assay developed in this study will serve as a promising tool for etiological and epidemiological studies of FCV circulating in Korea. Furthermore, the prevalence data obtained in this study will contribute to expanding knowledge about the epidemiology of FCV in Korea.

• 한국식품과학회지
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• 제39권1호
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• pp.71-76
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• 2007

본 연구에서는 노로바이러스의 대체모델인 feline calicivirus(FCV)를 이용하여 식품 중에 존재하는 식중독 바이러스의 신속검출방법을 개발하였다. 일반적으로 식품 중에 존재하는 식중독 바이러스를 검출하기 위해서는 식품으로부터 바이러스를 분리시키고, 분리된 바이러스를 농축한 뒤 RT-PCR 방법을 이용하여 검출하는데, 각각의 과정을 수행하는 데 있어서 다양한 문제점이 존재하고 있다. 첫째, 식품으로부터 바이러스를 분리하고 농축하는 과정에서 시간이 많이 걸린다는 것과 둘째, 농축하여 추출된 바이러스 RNA로 RT-PCR 방법을 수행하는데 있어서 잔존하는 식품 성분이 PCR 반응을 저해하여 검출효율이 낮아지는 문제점이 있다. 본 연구에서는 0.2 ${\mu}m$ syringe filter를 사용하여 바이러스 분리과정에서 PCR 저해물질인 식품성분을 추가적으로 제거시켰으며, 농축과정에서는 분쇄된 얼음에 방치하는 방법을 사용하여 overnight하는 과정을 3시간으로 단축시켰다. 농축된 바이러스의 RNA 추출물에 잔존하는 PCR 저해물질을 희석함으로서 보다 높은 검출효율을 얻을 수 있었다. 본 연구를 통해 개발된 신속검출법은 굴과 상추에서 노로바이러스의 신속검출을 위한 방법으로 적용이 가능할 것으로 판단되며, 또한 다양한 식품에서 식중독 바이러스의 검출 효율을 향상시키는데 기여할 것으로 생각된다.

• Journal of Veterinary Science
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• 제22권3호
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• pp.38.1-38.17
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• 2021

Background: The feline viral rhinotracheitis, calicivirus, and panleukopenia (FVRCP) vaccine, prepared from viruses grown in the Crandell-Rees feline kidney cell line, can induce antibodies to cross-react with feline kidney tissues. Objectives: This study surveyed the prevalence of autoantibodies to feline kidney tissues and their association with the frequency of FVRCP vaccination. Methods: Serum samples and kidneys were collected from 156 live and 26 cadaveric cats. Antibodies that bind to kidney tissues and antibodies to the FVRCP antigen were determined by enzyme-linked immunosorbent assay (ELISA), and kidney-bound antibody patterns were investigated by examining immunofluorescence. Proteins recognized by antibodies were identified by Western blot analysis. Results: The prevalences of autoantibodies that bind to kidney tissues in cats were 41% and 13% by ELISA and immunofluorescence, respectively. Kidney-bound antibodies were observed at interstitial cells, apical border, and cytoplasm of proximal and distal tubules; the antibodies were bound to proteins with molecular weights of 40, 47, 38, and 20 kDa. There was no direct link between vaccination and anti-kidney antibodies, but positive antibodies to kidney tissues were significantly associated with the anti-FVRCP antibody. The odds ratio or association in finding the autoantibody in cats with the antibody to FVRCP was 2.8 times higher than that in cats without the antibody to FVRCP. Conclusions: These preliminary results demonstrate an association between anti-FVRCP and anti-cat kidney tissues. However, an increase in the risk of inducing kidney-bound antibodies by repeat vaccinations could not be shown directly. It will be interesting to expand the sample size and follow-up on whether these autoantibodies can lead to kidney function impairment.

• Fisheries and Aquatic Sciences
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• 제13권2호
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• pp.96-101
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• 2010

Norovirus, which causes gastroenteritis in humans, is an important food-borne pathogen worldwide. In an effort to discover an antiviral substance against norovirus, extracts from several seaweeds were evaluated for antiviral activity against feline calicivirus (FCV), which was used as a surrogate. The methanolic extract of Undaria pinnatifida exhibited the most significant antiviral activity and virucidal efficacy against FCV. The concentrations of the extract that reduced viral replication by 50% ($EC_{50}$) and resulted in the death of 50% of the host cells ($CC_{50}$) were 0.05 mg/mL and 1.02 mg/mL, respectively. The selectivity index, calculated from the ratio of the $CC_{50}$ and $EC_{50}$ was 20.4. No FCV infection of host cells occurred following a 1-h incubation in the presence of 12.50 mg/mL U. pinnatifida extract, indicating that the virus was completely inactivated by the extract treatment. The results obtained in this study will contribute to the development of a natural antiviral substance that will prevent food-borne disease caused by norovirus.

• Journal of Veterinary Science
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• 제22권5호
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• pp.73.1-73.11
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• 2021

Background: Feline calicivirus (FCV) is a common pathogen of felids, and FCV vaccination is regularly practiced. The genetic variability and antigenic diversity of FCV hinder the effective control and prevention of infection by vaccination. Improved knowledge of the epidemiological characteristics of FCV should assist in the development of more effective vaccines. Objectives: This study aims to determine the prevalence of FCV in a population of cats with FCV-suspected clinical signs in Hangzhou and to demonstrate the antigenic and genetic relationships between vaccine status and representative isolated FCV strains. Methods: Cats (n = 516) from Hangzhou were investigated between 2018 and 2020. The association between risk factors and FCV infection was assessed. Phylogenetic analyses based on a capsid coding sequence were performed to identify the genetic relationships between strains. In vitro virus neutralization tests were used to assess antibody levels against isolated FCV strains in client-owned cats. Results: The FCV-positive rate of the examined cats was 43.0%. Risk factors significantly associated with FCV infection were vaccination status and oral symptoms. Phylogenetic analysis revealed a radial phylogeny with no evidence of temporal or countrywide clusters. There was a significant difference in the distribution of serum antibody titers between vaccinated and unvaccinated cats. Conclusions: This study revealed a high prevalence and genetic diversity of FCV in Hangzhou. The results indicate that the efficacy of FCV vaccination is unsatisfactory. More comprehensive and refined vaccination protocols are an urgent and unmet need.

• 한국식품위생안전성학회지
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• 제29권1호
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• pp.31-39
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• 2014

본 연구에서는 FCV 현탁액에 물리, 화학적 위생처리 후 복합효소처리라는 전처리과정을 적용한 뒤 real-time RT-PCR법을 이용하여 살균효능을 분석하였다. RT-PCR 이전에 $37^{\circ}C$에서 30분 동안 PK와 RNase A를 처리함으로써 UV, 열, 염소, 에탄올, 과초산계열 제품에 의해 불활성화 된 바이러스들은 음성 결과를 나타내었고, real-time RTP-CR법을 통해 살균 효능을 정량분석한 결과, 복합효소처리를 했을 경우 무처리구보다 더 높은 살균 효능을 보이는 것을 확인할 수 있었다. 이로써 Nuanualsuwan S. 등의 선행연구에서와 같이 PK와 RNase A로 전처리하는 단계를 통하여 물리, 화학적 위생처리에 의해 손상되지 않은 바이러스가 RT-PCR법에 의해 증폭되는 것을 방지함으로써 Real-time PCR법에 대한 검출 감도를 높일 수 있음을 확인하였다. 또한, FCV를 검출하기 위해 사용된 RT-PCR과 real-time RT-PCR 두 방법 중에서도 real-time RT-PCR법이 가장 신속하면서도 민감도 높은 결과로 도출되었다. 따라서, 유전자 분석 이전에 복합효소처리는 물리, 화학적 위생처리에 의해 불활성화 된 바이러스의 RNA가 transcription 또는 증폭되는 것을 방지하기 위한 수단으로 real-time RT-PCR법과 결합됨으로써 노로바이러스를 비롯한 식중독 바이러스를 검출하는데 효과적으로 적용될 것으로 판단된다. 또한 식품현장에서 전기영동 과정없이 신속하게 살아있는 바이러스만을 수치적으로 정량화함으로써 식품안전에도 기여할 것으로 사료된다.

• 한국동물위생학회지
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• 제46권4호
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• pp.269-281
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• 2023

In this study, a new triplex real-time quantitative reverse transcription polymerase chain reaction (tqRT-PCR) assay was developed for the rapid and differential detection of three feline viral pathogens including feline calicivirus (FCV), feline herpesvirus 1 (FHV-1), and influenza A virus (IAV) in a single reaction. The assay specifically amplified three targeted viral genes with a detection limit of below 10 copies/reaction. The assay showed high repeatability and reproducibility, with intra- and inter-assay coefficients of variation of less than 1%. Based on the diagnostic results of the assay using 120 clinical samples obtained from cats with feline respiratory disease complex (FRDC)-suspected signs, the prevalence of FCV, FHV-1, or IAV was 43.3%, 22.5%, or 0%, respectively, indicating that the diagnostic sensitivity was comparable or superior to those of previously reported monoplex qRT-PCR/qPCR assays. The dual infection rate for FCV and FHV-1 was 8.3%. These results indicate that FCV and FHV-1 are widespread and that co-infection with FCV and FHV-1 frequently occur in the Korean cat population. The developed tqRT-PCR assay will serve as a promising tool for etiological and epidemiological studies of these three bacterial pathogens, and the prevalence data for three feline viruses obtained in this study will contribute to expanding knowledge about the epidemiology of FRDC in the current Korean cat population.

• 한국수산과학회지
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• 제42권3호
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• pp.232-237
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• 2009

Norovirus surrogate (feline calicivirus) was inactivated by treatment at 50,000 psi for 60 sec by 6.8-$log_{10}TCID_{50}mL^{-1}$. Tissue obtained from oyster (digestive gland, gill and mantle) was qualitatively destroyed and distorted by treatment at pressure greater than 5,000 psi for 60 sec. High pressure treatment induced progressive changes in the color of the oyster adductor muscle. High pressure treatment effectively reduced norovirus surrogate but induced conformational changes in the tissue and color of oyster flesh.

• 생약학회지
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• 제50권1호
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• pp.1-10
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• 2019

Recently, companion animal culture has grown rapidly and mature, raising interest in preventing and treating animal diseases. In particular, viral infection was a serious threat to companion animal health because there was no proper antiviral drugs. Synthetic antiviral drugs have limitations such as low efficiency, toxicity, and occurrence of resistant viruses. Therefore, attempts to find new anti-viral drugs from natural sources have continued. This review focused on the natural products and active substances that exhibit antiviral activity against three viruses: canine distemper virus (CDV), canine parvovirus (CPV), and feline calicivirus (FCV) that cause fatal diseases in dogs and cats. Natural plant extracts, flavonoids, polysaccharides, alkaloids and saponins showed antiviral activity with various mechanisms and differences in activity depending on the structure. Especially, quercetin and epigallocatechin-3-gallate (EGCG) showed antiviral activity through a multi-mechanism that interferes with the attachment and penetration stages of the virus and inhibits the viral polymerase within the cell. Some natural plant extracts showed a virucidal activity and showed the potential effect as a preventative agent to prevent the viral infection. This review is expected to provide research trend on the development of antiviral natural products for companion animals.

• 대한수의학회지
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• 제62권3호
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• pp.24.1-24.7
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• 2022

Incidences of major feline viral diseases provide basic information for preventing viral disease in cats. Despite the growing interest in feline viral diseases, sero-surveillances have been lacking. In this study, we analyzed the diagnoses of feline viral diseases and conducted a sero surveillance of feline panleukopenia virus (FPV), feline calicivirus (FCV), feline herpesvirus-1 (FHV-1), and feline infectious peritonitis virus (FIPV) in Korean cats. Of the 204 confirmed cases since 2015, the numbers of diagnoses for FPV, FIPV, FCV, feline influenza virus, and FHV-1 were 156, 32, 12, 3, and 1 case, respectively. In total, 200 sera, collected between 2019 and 2021, were screened for the presence of antibodies against FPV, 2 FCVs, FHV-1, and FIPV using a hemagglutination inhibition test and a virus-neutralizing assay (VNA). The overall seropositive rates in cats tested for FPV, the 2 FCVs, FHV-1, and FIPV were 92.5%. 42.0%, 37.0%, 52.0%, and 14.0%, respectively. A low correlation (r = 0.466) was detected between the VNA titers of 2 FCV strains. The highest incidence and seropositive rate of FPV reveal that FPV is circulating in Korean cats. The low r-value between 2 FCVs suggests that a new feline vaccine containing the 2 kinds of FCVs is required.