Geographical clustering of Hantavirus isolates from Apodemus agrarius identified in the Republic of Korea indicate the emergence of a new Hantavirus genotype.

AIM AND METHODOLOGY: Several studies on hantavirus evolution have shown that genetic reassortment plays an important role in the evolution and epidemiology of this disease. To understand the genetic epidemiology of human hantaviruses, samples from rodent reservoirs were subjected to reverse-transcription nested polymerase chain reaction (RT-N-PCR) targeting the L- and S-segments of the hantavirus genome. RESULTS: Positive isolates from Gwangju, Boseong-gun (Jeollanam-do Province), and Jeju Island were confirmed as Hantaan virus using DNA sequencing. Phylogenetic analysis showed that all isolates grouped together as Hantaan virus but with each region forming a distinct cluster. In addition, these three clusters were distinct from other Hantaan isolates reported in previous studies from Korea and its neighboring countries China and Russia. CONCLUSION: This suggests Hantaan viruses exhibit a considerable degree of geographical clustering, and there may be a novel Hantaan genotype in southwestern ROK. This study helps expand our knowledge regarding the emergence of new hantavirus strains and their degree of geographical variation. IMPORTANCE: Hantaan virus, a pathogenic prototype hantavirus carried by Apodemus agrarius, is found throughout China, Russia, and Korea. Here, we examined the genetic diversity of hantaviruses to expand our knowledge regarding the emergence of new hantavirus strains and their degree of geographical variation. We found that hantaan viruses show a considerable degree of geographical clustering, which may allude to the development of a new genotype variant in the southwestern region of the ROK.

Comparison of RT-PCR, RT-nested PCRs, and real-time PCR for diagnosis of severe fever with thrombocytopenia syndrome: a prospective study.

We designed a highly sensitive reverse transcription nested polymerase chain reaction targeting the M-segment (NPCR-M) of severe fever with thrombocytopenia syndrome (SFTS) virus. NPCR-M was performed in parallel with three other referenced PCR assays QPCR-S, PCR-M, and NPCR-S to assess their clinical usefulness as routine diagnostic techniques for SFTS. In this multi-centered prospective study, 122 blood samples from 38 laboratory-confirmed SFTS patients and 85 control samples were used. The results demonstrated that QPCR-S and NPCR-S had better sensitivity rate up to 21 days after symptom onset however, the PCR-M showed poor sensitivity after 7 days of symptom onset. Our designed NPCR-M had a higher detection rate up to 40 days from symptom onset and revealed the persistence of SFTSV RNA in the early convalescent phase. No false-positive results were seen for the control samples. Additionally, NPCR-M showed positive results for a sample that initially showed negative results from other PCRs and for many other samples collected in the convalescent phase of SFTS. Our designed nested PCR is suitable for SFTSV detection in patients' blood collected in the acute and early convalescent phase of SFTS, and shows better sensitivity and high specificity even up to 40 days after symptom onset.

Hemorrhagic Fever with Renal Syndrome as a Cause of Acute Diarrhea.

Hemorrhagic fever with renal syndrome (HFRS) is a febrile disorder caused in Korea by the Hantaan and Seoul viruses. Its characteristic clinical manifestations include fever, hemorrhage, and renal failure, but a primary presentation with acute infectious diarrhea is rare. Owing to decreased urine output and renal function, a 54-year-old patient was transferred to our hospital from a local clinic, where he had been receiving treatment for diarrhea occurring more than 10 times a day. The patient was treated in the Gastroenterology Department at our hospital for acute renal failure secondary to inflammatory diarrhea based on the findings of stool leukocytes. An immunofluorescent antibody assay showed a 4-fold increase in the acute-phase antibody titer to Hantavirus during recovery. A nested reverse transcription polymerase chain reaction (RT-nPCR) assay of plasma yielded negative results, but Hantaan virus positivity was confirmed on an RT-nPCR assay of the buffy coat. Another 60-year-old patient with watery diarrhea was treated conservatively for suspected infectious diarrhea. However, an immunofluorescent antibody assay showed a 4-fold increase in the acute-phase HFRS antibody titer. RT-nPCR using plasma yielded negative results, but Seoul virus was detected on an RT-nPCR buffy coat assay, confirming the diagnosis of HFRS. Hemorrhagic fever with renal syndrome can present with gastrointestinal symptoms such as acute diarrhea alone. This report highlights the importance of considering HFRS in the differential diagnosis of patients with acute diarrhea and the need for additional research on the usefulness of the buffy coat in the PCR diagnosis of HFRS.

Molecular detection of viruses causing hemorrhagic fevers in rodents in the south-west of Korea.

Many pathogens causing hemorrhagic fevers of medical and veterinary importance have been identified and isolated from rodents in the Republic of Korea (ROK). We investigated the occurrence of emerging viruses causing hemorrhagic fevers, such as hemorrhagic fever with renal syndrome (HFRS), severe fever with thrombocytopenia syndrome (SFTS), and flaviviruses, from wild rodents. Striped field mice, Apodemus agrarius (n = 39), were captured during 2014-2015 in the south-west of ROK. Using molecular methods, lung samples were evaluated for SFTS virus, hantavirus, and flavivirus, and seropositivity was evaluated in the blood. A high positive rate of hantavirus (46.2%) was detected in A. agrarius lungs by reverse transcription-nested polymerase chain reaction (RT-N-PCR). The monthly occurrence of hantavirus was 16.7% in October, 86.7% in November, and 25% in August of the following year (p < 0.001). Moreover, 17.9% of blood samples were serologically positive for hantavirus antibodies. The most prevalent strain in A. agrarius was Hantaan virus. All samples were positive for neither SFTS virus nor flavivirus. Hantaan virus was detected in 86.7% of A. agrarius in November (autumn), and thus, virus shedding from A. agrarius can increase the risk of humans contracting HFRS. These findings may help to predict and prevent disease outbreaks in ROK.