Seroepidemiological Survey of Hantavirus Infection of Wild Rodents Trapped from 1994 to 1998 in Korea

Hantaviruses belong to the genus Hantavirus and Hantaan, Seoul, Puumala, Belgrade and Sin Nombre viruses are the etiolgic agents of two serious hantaviral diseases of humans. The rodent hosts and the specific etiologic agents of haemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS) are known and many reported cases occurred in Eurasia and Americas. Wild rodents trapped in 13 different areas of Korea from 1994 to 1998 were investigated against hantavirus infection. A total of 718 wild rodents and 10 species were trapped and found 630 (87.7%) of them were Apodemus agrarius. Indirect immunofluorescent antibody technique (IFAT) was performed for hantaviruses infections using different hantavirus antigens. Hantavirus antibodies were found in 68 (10.8%) out of 630 A. agrarius, 8 (42.1%) of 19 Rattus norvegicus. Among 68 lungs and other tissues of antibody positive A. agrarius, 5 (7.4%) were antigen positive. IFA titers of 5 positive A. agrarius sera showed higher titers against Puumala or Sin Nombre viruses than Hantaan virus. These results suggest that there may be are possibilities of existence of a noble hantavirus in Korean wild rodents.

Molecular Characterization of Hantavirus Isolated from Bandicota indica Captured in Indonesia and Thailand

No Abstract Available.

An Immunoserological Study of Vaccine Against Haemorrhagic Fever with Renal Syndrome

Since HantavaxTM, formalin inactivated Hantaan virus vaccine (10,240 ELISA units/ml), has been developed in 1990 to prevent against haemorrhagic fever with renal syndrome (HFRS) caused by Hantaan or Seoul virus, it has been commercially available in Korea. Twenty-one healthy people were booster shot once and twice after primary basic vaccination with HantavaxTM. Seroconversion rates were measured by immunofluorescent antibody technique (IFAT), enzyme-linked immunosorbent assay (ELISA), high density composite particle agglutination (HDPA), and plaque reduction neutralization test (PRNT). Seroconversion rates of 21 vaccinees at one year after primary basic vaccination were 52.3%, 95.2%, 0.0%, 47.6%, and 28.6%, and 13 vaccinees of one month after 1st booster vaccination were 100%, 100%, 30.7%, 100% and 100% by IFAT, ELISA (IgG, IgM), HDPA and PRNT, respectively. Seroconversion rates declined slightly by twenty months, and they were 84.6%, 92.3%, 0.0%, 84.6% and 69.2% by IFAT, ELISA (IgG, IgM), HDPA and PRNT, respectively. Seroconversion rates of 9 vaccinees at three months after 2nd booster vaccination were 100%, 100%, 0.0%, 100%, and 88.9%, and 16 vaccinees at one year after the 2nd booster vaccination were 87.5%, 93.8%, 0.0%, 87.5% and 81.3% by IFAT, ELISA (IgG, IgM), HDPA and PRNT, respectively. Based on the above result HantavaxTM has proved a vigorous anamnestic response after the 1st and the 2nd booster vaccination and has persisted higher fluorescence, agglutination and neutralizing antibody titers in vaccinees.

Molecular Characterization of the L Segment of Hantann Virus, Strain Howang

Hantaan virus (HTNV), the etiologic agent of hemorrhagic fever with renal syndrome (HFRS), belongs to the genus Hantavirus, and has three single negative straded RNA genome segments. HTNV strain Howang isolated from the blood of severe case of Korean HFRS is more virulent than HTNV 76/118 and the M and S genome segments' nucleotide sequence of Howang strain showed 93.5% and 94% homology to each segment of HTNV 76/118. We have obtained 6533 nucleotides long sequence of the L genome segment of Howang strain using reverse transcriptase in conjunction with PCR amplification and compared to other hantaviruses. The messenger sense of the L segment contains one long single long open reading frame of 2151 amino acids, which encodes a deduced RNA dependent RNA polymerase of 246.4 kDa caculated molecular weight protein. The nucleotide sequence of the Lsegment of Howang strain shows 93%, 74%, 66%,65% homology to HTNV 76/118, Seoul virus 80/39, Puumala virus Hallnas B1 and Sin Nombre virus, respectively. The amino acid sequence of the L segment of Howang strain shows 99%, 85%, 68%, 68% homology to HTNV 76/118, Seoul virus 80/39, Puumala virus Hallnas B1 and Sin Nombre virus, respectively.

Epidemiological Analysis of Viral Respiratory Infections and Comparison of Isolation Rate of Various Clinical Specimens / 감염

BACKGROUND: We studied the epidemics of respiratory viral infections in Korea and examined various respiratory tract specimens for the presence of respiratory viruses, since the accuracy of rapid detection method depends, in part, on the source of the specimens. METHODS: Over a 24-month period, from March 1997 through February 1999, a total of 1,574 clinical specimens were submitted for the detection of respiratory viruses. A shell vial technique with commercially available monoclonal antibodies directed against respiratory viruses was used to detect respiratory syncytial virus, adenovirus, influenza virus, and parainfluenza virus in clinical specimens, which included throat swab, nasopharyngeal aspirate, tracheal aspirate, and bronchoalveolar lavage (BAL) fluid. RESULTS: Overall positive rate of respiratory viruses was 73/1574 (4.6%). Respiratory viruses were predominantly found between December and February. High incidences were observed among those younger than 2 years and those older than 50 years. The numbers of viral isolates were 3/69 (4.3%) for throat swab, 26/459 (5.7%) for nasopharyngeal aspirate, 11/315 (3.2%) for tracheal aspirate, and 30/528 (5.7%) for BAL fluid. CONCLUSIONS: Nasopharyngeal aspirate and BAL fluid appear to permit increased detection of the respiratory viruses compared with throat swab or tracheal aspirate. However, throat swab may be good specimen for the detection of influenza virus and parainfluenza virus.

Isolation of the Hantaviruses from the Lungs of Bandicota indica Captured in Indonesia and Thailand

Various hantaviruses were isolated from HFRS patients and various rodent species, in many parts of the world. Bandicotas were captured at Yogyakarta, east region of Sumatura island, Indonesia; and 4 rodents species including Bandicotas were captured at Chiang Rai in Thailand during 1995. Sera were collected from captured andicotas and other rodent spicies were screened for antibody test against Hantaan (HTN), Seoul (SEO), Puumala (PUU) and Sin Hombre (SN) viruses by immunofluoresence antibody assay (IFA). Hantavirus antigen in lung tissues were tested by IFA. Among 55 captured Bandicota indica in Indonesia, 14 (25.5%) were antibody positive against HTN, SEO, PUU and SN virus. Hantavirus antigen were detected from 5 (9.0%) out of 55 lungs tested. Among 34 captured Bandicota indica in Thailand, 9 (26.5%) were antibody positive against HTN, SEO, PUU and SN virus. Among 34 lungs tissues of Bandicota indica examined, 3 (8.8%) were antigen positive. In other rodent species, antibody positive against Hantaviruses of Rattus rattus, Rattus losea and Mus cervicolor were 4/62(6.5%), 5/25(20%), 1/1(100%), respectively. But no one has antigen in their lung tissues. Antigen positive lungs suspension were inoculated into vero E6 cells for virus isolation and 4 viruses were isolated from Indonesian Badicota and 3 viruses from Thailand.

Immune Response and Antibody Persistence against Hantaan Virus of Vaccinees with Hantavax(TM) / 감염

BACKGROUND: Hantavax(TM) was developed for preven-tion of hemorrhagic fever with renal syndrome caused by Hantaan or Seoul virus in 1990, and has been commer-cially available in Korea since then. Because Hantavax (TM) has such short usage history, the duration of antibody persistency in vaccinees has not been well studied. METHODS: 61 healthy people were immunized subcu-taneously with Hantavax (TM) twice at one month intervals as primary vaccination. 21 vaccinees were tested at 1 ~4 months after primary vaccination and 40 vaccinees were tested at one year after primary vaccination and then one month and 1 ~2 years after booster vaccination. Antibody titers were measured by immunofluorescent assay(IFA), Hantaan virus antigen-coated high density particle agglu-tination assay(HDPA), and plaque reduction neutralization test(PRNT). RESULTS: Seroconversion rates of 21 vaccinees at 1 ~ 4 months after primay vaccination were 20/21(95.2%), 19/21(90.5%) and 14/21(66.7%); seropositivity of 40 vaccinees at one year after primary vaccination was 25/40 (62.5%), 18/40(45.0%), and 9/40(22.5%) by IFA, HDPA, and PRNT, respectively. Seroconversion rates of 8 vaccinees at one month after booster vaccination were 8/ 8(100 %), 8/ 8(100%); antibody persistence rate of 11 vaccinees at 20 months after booster vaccination were 11/ 12 (91.7%), 9/ 12(75.0%), and seroconversion rates of 7 vaccinees at 3 months after second booster vaccination were 7/7(100%) and 6/7(85.7%) by IFA and PRNT, respectively. Geometric mean antibody titers of 21 vaccinees at 1-4 months after primary basic vaccination were 262, 248, 120; and those of 40 vaccinees at one year after primary vaccination were 90, 56, and 24 by IFA, HDPA, and PRNT, respectively. Geometric mean antibody titers of 8 vaccinees at one month after booster vaccination were 852, 183, of 12 vaccinees at 20 months after booster vaccination were 296, 33, and of 7 vaccinees at 3 months after second booster vaccination were 549 and 46 by IFA and PRNT, respectively. CONCLUSION: The booster vaccination is necessary at 12 months after primary vaccination to maintain high levels of antibodies which persist at least two years after booster vaccination.

Immune Reaction of the Vaccinated Hamsters with Combined Hantaan-Puumala Vaccine

A large number of viruses belonging to Genus Hantavirus in Family Bunyaviridae are etiologic agents for hemorrhagic fever with renal syndrome (HFRS), or hantavirus pulmonary syndrome (HPS). Hantaan (HTN), Seoul (SEO), Belgrade (BEL), Puumala (PUU) serotype viruses are well known causative agents for HFRS in Eurasian continent. Among those viruses Hantaan and Seoul serotypes are well known to cause HFRS in Korea, but there are some sporadic incidence by other than Hantaan or Seoul viruses. Recently we have developed the combined Hantaan-Puumala virus vaccine to prevent world-wide occurring HFRS. This combined vaccine is formalin inactivated, suckling mouse and suckling hamster brain extracts for Hantaan and Puumala viruses, respectively. Protein contents of this purified candidate vaccine is 27 microgram/ml, which contains 1,024 ELISA antigen units to each virus, but content of myelin basic protein which is causing experimental allergic encephalomyelitis is legs than 0.1 ng/ml. Thirty hamsters were given twice at one month interval intra-muscularly and bled on 30 days after each vaccination from retro-orbital sinus vein. Antibody titers were tested against 5 major serotype viruses, Hantaan, Seoul, Belgrade, Puumala and Sin Nombre viruses by IFA and PRNT. The mean IF antibody titers on 30 days after primary shot were 78.4, 68.8, 68.8, 37.9, and 15.6; mean neutralizing antibody titers were 65.4, 12, 6.1, 65.6 and 0.5 against Hantaan, Seoul, Belgrade, Puumala and Sin Nombre viruses, respectively. The mean IF antibody titers on 30 days after booster shot were 686.9, 567.5, 550.4, 516.3, and 430.9; and neutralizing antibody titers were 710.8, 41.9, 24.3, 409.9, and 1.6 against Hantaan, Seoul, Belgrade, Puumala and Sin Nombre viruses, respectively.

Discrimination of Hantaviruses from the Tissues of Infected Hamsters to 5 Different Serotype Hantaviruses by Nested RT-PCR using Hantavirus Serotype Specific Primers

We developed a sensitive, nested reverse transcription-polymerase chain reaction (RT-PCR) to detect Hantaan, Seoul, Belgrade, Puumala and Sin Nombre viruses in animal tissues. Total RNA was extracted from blood, lung or kidney samples of experimentally-infected hamsters by using the guanidine isothiocyanate buffer-acid phenol-chloroform method. Genus-reactive outer primers were derived from the consensus region of the G1 gene sequences of several hantaviruses. Serotype-specific primers were selected within the region amplified by the outer primers. To examine the sensitivity and specificity of the test, we diluted known quantities of Hantaan, Seoul, Belgrade, Puumala and Sin Nombre viruses in human or hamster immune sera before performing the nested RT-PCR. We could detect as little as 1 pfu of virus, even in the presence of high-titer neutralizing antibodies, and the serotype-specific primers amplified only homologous serotype viruses. RT-PCR with these primers demonstrated virus in the blood of experimentally-infected hamsters as early as four days to as late as 30 days after infection.4 comparison of a standard immunofluorescent antibody screening test (IFAT) to nested RT-PCR with RNA extracted from lung or kidney tissues of the hamsters, demonstrated that RT-PCR to be more sensitive for identifying viruses in these tissues.

Molecular Characterization of a New Hantaan Virus Howang Strain

Hantaan virus Howang strain which isolated from the blood of severe case of Korean hemorrhagic fever is more virulent than HTN 76/118 and showed different RFLP from partial PCR amplified M genome segment to established Hantaan serotype viruses. We have determined the nucleotide sequence of the M and S genome segments and compared to HTN 76/118. The M and S segment of Howang strain has 3615 and 1696 nucleotides long, respectively. The M segment sequence of Howang strain is one mucleotide shorter than HTN 76/118. The sequence data of Howang strain shows 93.5% homology to HTN 76/118. One long open reading frame, which stoats from 41nt. to 3448nt. of the M segment and from 37nt. to 1326nt. of the S segment, exist to on complementary sense of the virus genome. There are no significant difference between HTN 76/118 and Howang strain on hydrophobicity of deduced polypeptides, but has slight difference on secondary structure.

Seroepidemiologic survey of residents and urban rats against the etiologic agents of hemorrhagic fever with renal syndrome in Singapore

No abstract available.