• Korean Journal of Clinical Laboratory Science
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• v.42 no.1
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• pp.1-15
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• 2010

Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) is endemic in swine, and classified into influenza A and influenza C but not influenza B. Swine influenza A includes H1N1, H1N2, H3N1, H3N2 and H2N3 subtypes. Infection of SIV occurs in only swine and that of S-OIV is rare in human. What human can be infected with S-OIV is called as zoonotic swine flu. Pandemic 2009 swine influenza H1N1 virus (2009 H1N1) was emerged in Mexico, America and Canada and spread worldwide. The triple-reassortant H1N1 resulting from antigenic drift was contained with HA, NA and PB1 of human or swine influenza virus, PB2 and PA polymerase of avian influenza virus, and M, NP and NS of swine influenza virus, The 2009 H1N1 enables to transmit to human and swine. The symptoms and signs in human infected with 2009 H1N1 virus are fever, cough and sore throat, pneumonia as well as diarrhea and vomiting. Co-infection with other viruses and bacteria such as Streptococcus pneumoniae can occur high mortality in high-risk population. 2009 H1N1 virus was easily differentiated from seasonal flu by real time RT-PCR which contributed rapid and confirmed diagnosis. The 2009 H1N1 virus was treated with NA inhibitors such as oseltamivir (Tamiflu) and zanamivir (Relenza) but not with adamantanes such as amantadine and rimantadine. Evolution of influenza virus has continued in various hosts. Development of a more effective vaccine against influenza prototypes is needed to protect new influenza infection such as H5 and H7 subtypes to infect to multi-organ and cause high pathogenicity.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.63-70
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• 2010

Novel influenza A (H1N1) is a newly emerged flu virus that was first detected in April 2009. Unlike the avian influenza (H5N1), this virus has been known to be able to spread from human to human directly. Although it is uncertain how severe this novel H1N1 virus will be in terms of human illness, the illness may be more widespread because most people will not have immunity to it. In this study, we compared the codon usage bias between the novel H1N1 influenza A viruses and other viruses such as H1N1 and H5N1 subtypes to investigate the genomic patterns of novel influenza A (H1N1). Totally, 1,675 nucleotide sequences of the hemagglutinin (HA) and neuraminidase (NA) genes of influenza A virus, including H1N1 and H5N1 subtypes occurring from 2004 to 2009, were used. As a result, we found that the novel H1N1 influenza A viruses showed the most close correlations with the swine-origin H1N1 subtypes than other H1N1 viruses, in the result from not only the analysis of nucleotide compositions, but also the phylogenetic analysis. Although the genetic sequences of novel H1N1 subtypes were not exactly the same as the other H1N1 subtypes, the HA and NA genes of novel H1N1s showed very similar codon usage patterns with other H1N1 subtypes, especially with the swine-origin H1N1 influenza A viruses. Our findings strongly suggested that those novel H1N1 viruses seemed to be originated from the swine-host H1N1 viruses in terms of the codon usage patterns.

• Korean Journal of Microbiology
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• v.55 no.1
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• pp.25-32
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• 2019

Influenza A (H1N1) virus caused a worldwide pandemic in 2009-2010 and still remains in seasonal circulation. Continuous surveillance activities are encouraged in the post pandemic phase to watch over the trend of occurrence every year, this is better to be done by a rapid and sensitive method for its detection. This study was conducted to detect proportions of occurrence of influenza A virus (H1N1) in patients with influenza-like illness. Samples from 500 patients with influenza or influenza-like clinical presentation were tested by real-time reverse transcription polymerase chain reaction (RT-PCR) and virus tissue culture. Among the total 500 participants, 193 (38.6%) were females and 307 (61.4%) males. Seventy-one patients (14.2%) were positive for H1N1 virus infection with real-time RT-PCR while 52 (10.4%) were positive by tissue culture. Non-statistically significant relation was found between age and gender with the positivity of H1N1. Sensitivity and specificity of real-time RT-PCR was 98.08% and 95.54%, respectively, in comparison to virus isolation with accuracy 95.8%. This study showed that H1N1 virus was responsible for a good proportion of influenza during the post-pandemic period. Real-time RT-PCR provides rapidity and sensitivity for the detection of influenza A virus (H1N1) compared with virus isolation and thus it is recommended as a diagnostic tool.

• Korean Journal of Veterinary Research
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• v.38 no.1
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• pp.53-63
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• 1998

Total of 1085 swine sera (1996-1997) from nation-wide were tested for the presence of antibodies to influenza A virus. Fifty nine percent of the tested sera showed seropositive by HI test. Positive sera consisted of 24--- of H3, 15--- of H1, and 20--- of the sample had both antibodies, respectively. Sera collected from various region represented 7~27--- seropositivity to H1N1, 15~25--- to H3N2, respectively. Swine influenza field isolate from nasal swab was characterized antigenically and genetically to elucidate its relatedness with other known strains of influenza A virus. The study was focused on the HA gene which is related to pathogenecity and antigenic variability of the influenza virus. By RT-PCR using influenza A/H1N1 specific primers, influenza virus H1N1 specific DNA fragment was amplified from A/Swine/Iowa/15/30(H1N1), US field isolate but not in H3N2 strain. PCR products were sequenced by dideoxy chain termination method to determine nucleotide homology with other strains of influenza A virus. The US field isolate and A/Swine/Indiana/1726/88 strain had 97--- of nucleotide homology and 98--- of amino acid homology. Based on the results obtained from this experiment, the field isolate was genetically related to A/Swine/Indiana/1726/88 and had higher homology with A/Swine/Indiana/1726/88 than with classical swine influenza virus, A/Swine/Iowa/15/30. The field isolate had no amino acid changes at the antigenic site compare to that of the A/Swine/Indiana/1726/88. The proteolytic enzyme cleavage site between HA1 and HA2 had no alteration and the amino acid arginine was intact. There is no evidence has been found that the field isolate has genetic shift or genetic drift which might altered antigenic determinant.

• Journal of Life Science
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• v.30 no.9
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• pp.749-762
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• 2020

Influenza A viruses are circulating in a variety of hosts, including humans, pigs, and poultry. Swine influenza virus is a zoonotic pathogen that can be readily transmitted to humans. The influenza viruses of the 2009 H1N1 pandemic were derived from swine influenza viruses, and it has been suggested that the 1957 H2N2 pandemic and the 1968 H3N2 pandemic both originated in pigs. Pigs are regarded as a mixing vessel in the creation of novel influenza viruses since they are readily infected with human and avian influenza viruses. We isolated three novel H1N2 influenza viruses from pigs showing respiratory symptoms on a Korean farm in 2019. These viruses were reassortants, containing PA and NP genes from those of the 2009 H1N1 influenza virus in addition to PB2, PB1, HA, NA, M, and NS genes from those of triple-reassortant swine H3N2 and classical swine H1N2 influenza viruses circulating in Korean pigs. Mice infected with the isolated H1N2 influenza virus lost up to 17% body weight and exhibited interstitial pneumonia involving infiltration of many inflammatory cells. Results suggest that close surveillance to detect emerging influenza viruses in pigs is necessary for the health of both pigs and humans.

• Korean Journal of Clinical Laboratory Science
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• v.41 no.4
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• pp.145-152
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• 2009

Novel influenza A virus, subtype H1N1 of swine-lineage, has been transmitted rapidly to many regions of the world. Rapid detection of the virus is essential to instigate appropriate patient care and public health management and for disease surveillance. The aim of this study is to determine the prevalence of novel influenza A (H1N1) virus in Korea using reverse-transcription real time polymerase chain reaction (rRT-PCR). Novel H1N1 virus was detected in a total of 8,948 nasopharyngeal samples from patients with influenza-like illness throughout Korea from August to September 2009. RNA was extracted from $300{\mu}l$of sample using an RNA extraction kit (Zymo Research, CA, USA). In the present study, Genekam kit (Genekam, Duisburg, Germany) was used to detect novel H1N1 virus. Novel H1N1 virus was found in 1,130 samples from a total of 8,948 samples (12.6%). The highest frequency was found in 10- to 19-year-olds (M: 29.3% vs. F: 16.4%), followed by 20- to 29-year-olds (M: 17.9% vs. F: 15.4%), 40- to 49-year-olds (M: 6.5% vs. F: 8.1%), 50- to 59-year-olds (M: 6.0% vs. F: 5.5%), and 30- to 39-year-olds (M: 4.6% vs. F: 3.8%). The mean positive rate was higher in men than in women (M: 14.7% vs. F: 7.4%). Novel H1N1 virus showed the lowest prevalence in patients over 60 years old. The positive rate increased daily and showed a significant high peak in mid-September 2009. In 19 provinces of Korea, Cheonan (41.1%), Busan (37.3%), Gangneung (33.3%), Jinju (32.1%), Ulsan (24.6%), Deajeon (23.7%) areas showed high frequencies and other provinces were found less than 10% of novel H1N1 virus. Since reverse-transcription real time PCR assay is rapid, accurate, and convenient, it may assist public health laboratories in detecting novel H1N1 virus. Moreover, these data could be useful for the management of patients with influenza-like illness.

• Korean Journal of Veterinary Research
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• v.43 no.2
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• pp.271-281
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• 2003

Virulent and avirulent H5N1 viruses were inoculated intranasally to BALB/c and immunodeficient mice, and compared the pathogenesis by histology and immunohistochemistry. All of mice infected with virulent virus died by systemic infection at 6 to 7 days postinfection (PI). BALB/c mice infected with avirulent virus survived from the infection, whereas immunodeficient mice showed nervous symptoms in addition to respiratory disease and died at 13 days PI. Viral positive antigens was detected from multiple organs including central nervous system in immunodeficient mice infected with avirulent virus. These results suggest that avirulent H5N1 influenza virus can aquire the multiple tissue tropism under immunosuppresed condition and host immune system is a important factor to protect the development of disease.

• BMB Reports
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• v.45 no.11
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• pp.653-658
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• 2012

After the outbreak of the swine-origin influenza A H1N1 virus in April 2009, World Health Organization declared this novel H1N1 virus as the first pandemic influenza virus (2009 pH1N1) of the $21^{st}$ century. To elucidate the characteristics of 2009 pH1N1, the growth properties of A/Korea/01/09 (K/09) was analyzed in cells. Interestingly, the maximal titer of K/09 was higher than that of a seasonal H1N1 virus isolated in Korea 2008 (S/08) though the RNP complex of K/09 was less competent than that of S/08. In addition, the NS1 protein of K/09 was determined as a weak interferon antagonist as compared to that of S/08. Thus, in order to confine genetic determinants of K/09, activities of two major surface glycoproteins were analyzed. Interestingly, K/09 possesses highly reactive NA proteins and weak HA cell-binding avidity. These findings suggest that the surface glycoproteins might be a key factor in the features of 2009 pH1N1.

• Journal of Korean Academy of Nursing
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• v.41 no.3
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• pp.403-410
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• 2011

Purpose: This study was to identify the current status of vaccination against the pandemic (H1N1) 2009 virus among university students from the fields of nursing and allied health from a local community and verify factors influencing vaccination. Methods: The study included 227 students in the fields of nursing and allied health from a provincial university. Data were obtained from these participants between May 31 and June 11, 2010 by using self-report questionnaires. Results: The rate of vaccination against the pandemic (H1N1) 2009 virus for these participants was 14.5%. No difference was observed in this regard between majors and school year. Factors that influence vaccination against this virus included previous vaccination against seasonal influenza and participants’ attitudes toward general vaccination. Conclusion: The results suggest that for effective pandemic (H1N1) 2009 vaccination of university students from the fields of nursing and allied health, students who have not been vaccinated should be intensively managed. Developing a vaccination program that encourages a positive attitude toward vaccination is recommended.

• Journal of Microbiology and Biotechnology
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• v.22 no.5
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• pp.699-707
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• 2012

Since the 2009 pandemic human H1N1 influenza A virus emerged in April 2009, novel reassortant strains have been identified throughout the world. This paper describes the detection and isolation of reassortant strains associated with human pandemic influenza H1N1 and swine influenza H1N2 (SIV) viruses in swine populations in South Korea. Two influenza H1N2 reassortants were detected, and subtyped by PCR. The strains were isolated using Madin-Darby canine kidney (MDCK) cells, and genetically characterized by phylogenetic analysis for genetic diversity. They consisted of human, avian, and swine virus genes that were originated from the 2009 pandemic H1N1 virus and a neuraminidase (NA) gene from H1N2 SIV previously isolated in North America. This identification of reassortment events in swine farms raises concern that reassortant strains may continuously circulate within swine populations, calling for the further study and surveillance of pandemic H1N1 among swine.