Mechanism of Japanese encephalitis virus genotypes replacement based on human, porcine and mosquito-originated cell lines model

OBJECTIVE@#To examine the multiplication efficiency Japanese encephalitis virus (JEV) genotype I (GI) and genotype III (GIII) of different cell lines which originated from human, porcine, mosquitoes in order to prove mechanism of JEV GI replacement JEV GIII since it emerging in nature recent decades.@*METHODS@#The mixture of GI and GIII JEV isolates was inoculated on human rhabdomyosarcoma (RD), pig kidney epithelial (PS) and Aedes albopictus C6/36 clone (C6/36) which originated from human, porcine and mosquitoes, respectively. Plaque assays were performed to calculate virus titer and real-time RT-PCR with GI and GIII specific primer sets to quantify the number of GI and GIII RNA copies.@*RESULTS@#The highest virus titer reached at the 3rd day of post infection when GI and GIII mixture was inoculated on RD and PS and that of C6/36 was at the 4th day. JEVs were amplified and maintained by C6/36 cells after 10 passages whereas that by RD and PS only limited within 8 and 6 passages, respectively. GI strain amplified and maintained more efficiently on C6/36 and PS but not RD, whereas GIII strain amplified and maintained more efficiently on RD.@*CONCLUSIONS@#There is a correlation between the multiplication efficiency of GI and GIII JEV strains when these two genotype strains co-infected on different cell lines with the predominance of GI strains in C6/36 and PS and the limited detection of GI strains in RD cells proving a possible mechanism of shift JEV genotypes in nature recent decades since GI emerging.

Mechanism of Japanese encephalitis virus genotypes replacement based on human, porcine and mosquito-originated cell lines model

Objective: To examine the multiplication efficiency Japanese encephalitis virus (JEV) genotype I (GI) and genotype III (GIII) of different cell lines which originated from human, porcine, mosquitoes in order to prove mechanism of JEV GI replacement JEV GIII since it emerging in nature recent decades. Methods: The mixture of GI and GIII JEV isolates was inoculated on human rhabdomyosarcoma (RD), pig kidney epithelial (PS) and Aedes albopictus C6/36 clone (C6/36) which originated from human, porcine and mosquitoes, respectively. Plaque assays were performed to calculate virus titer and real-time RT-PCR with GI and GIII specific primer sets to quantify the number of GI and GIII RNA copies. Results: The highest virus titer reached at the 3rd day of post infection when GI and GIII mixture was inoculated on RD and PS and that of C6/36 was at the 4th day. JEVs were amplified and maintained by C6/36 cells after 10 passages whereas that by RD and PS only limited within 8 and 6 passages, respectively. GI strain amplified and maintained more efficiently on C6/36 and PS but not RD, whereas GIII strain amplified and maintained more efficiently on RD. Conclusions: There is a correlation between the multiplication efficiency of GI and GIII JEV strains when these two genotype strains co-infected on different cell lines with the predominance of GI strains in C6/36 and PS and the limited detection of GI strains in RD cells proving a possible mechanism of shift JEV genotypes in nature recent decades since GI emerging.

Detection of Japanese encephalitis genotype 1 in central, southern and highland of Viet Nam

Background: In recent year, Japanese Encephalitis Virus (JEV) genotype 1 has been detected among isolates from mosquitoes and pig\u2019s blood samples in northern Viet Nam, but there has been no information on the presence of this genotype in the Central, Southern and Highland regions. Objectives: This study aims to detect the Japanese encephalitis genotype 1 in various different geographic regions of Viet Nam. Material and method: Sequence analysis\u2019s of whole E gene of 18 strains isolated from human, mosquitoes and pig\u2019s blood during 2001-2007. Results: 7 strains isolated from pig\u2019s blood and mosquito samples in the Northern, Central, Southern and Highland fell into genotype 1, but 11 others isolated from humans in the Northern and Central regions belonged to genotype 3. Conclusion: This is the first time that JEV genotype 1 was detected in the central, northern, highland Viet Nam and further studies on genotype 1 causing human diseases needs to be carried out.\r\n', u'\r\n', u'

Evaluation of the quality of the IgM antibody capture ELISA diagnostic kit for the Japanese encephalitis virus produced by National Institute of Hygiene and Epidemiology

Background: IgM antibody capture ELISA (MAC-ELISA) technique has been widely applied for Japanese Encephalitis Virus (JEV) diagnosis. So far rare internationally commercial kits are available. Thus, the international evaluation of the kit is required as per the recommendation of the WHO. Objectives: To evaluate the quality of the IgM antibody capture ELISA diagnostic kit for JEV produced by the Vietnam National Institute of Hygiene and Epidemiology (NIHE). Subjects and method: In this study, NIID kit was used as control to check the kit from NIHE. Both NIHE and NIID kits were used to detect JEV IgM among 38 serum and 6 CFS samples, which belongs to 5 sample groups (JE patients group, dengue patients group, other viral encephalitis patients group, Tick Born Encephalitis (TBE) patient group and healthy JE vaccinated donors group). Results: The detection of JEV IgM by NIHE kit was concurrent with the NIID kit. There is no positive with the JE in the groups of Dengue patients, TBE, other virus encephalitis patients and JE vaccinated donors. Conclusion: MAC-ELISA kit of NIHE can be used for different diagnosis of JEV and Dengue virus (both viruses are in Flavivirus genus), as well as other viruses caused by encephalitis.

Study fluctuation and confirmation of Japanese encephalitis vector in Ha Nam province, 2006-2007 \r\n', u'\r\n', u'

Background: Japanese Encephalitis (JE) virus is a leading cause of encephalitis in children with high mortality and complication. JE is a dangerous infectious disease via Culex mosquitoes. Objective: To identify the density of some mosquitoes and vectors that transmit JE virus in Ha Nam province. Subject and Method:There were 30.333 mosquitoes including 05 genera and 15 species which were collected at night from April 2006 to March 2007 in the following communes: Tanson (midland area) Hungcong (plain area) and Liemchinh (suburban area). Results: A total of 06 Culex species, the highest rate is Culex tritaeniohychus (41.20%); Culex annulus (15.56%); other Culex species occupied around 0.15% -2.49%. In these communes, the density of Culex tritaeniohychus was higher than Culex annulus. They were found to be active all year round, but the highest density of Culex tritaeniohychus and Culex annulus is 5.86 and 2.15, respectively in April and fall to 4.35% and 1.71% in July. The collected mosquitoes during April, May, June and July includes 133 and 28 Culex tritaeniohychus and Culex annulus pools, respectively; all were to be processed for the isolation of Japanese Encephalitis (JE) virus. There were 12 Culex tritaeniohychus and 2 Culex annulus pools which were collected in Tanson commune yielding positive. Conclusion: The results were confirmed that Culex tritaenioohychus and Culex annulus are the major vectors that transmit JE virus in Ha Nam, 2006 - 2007. All 14 JE virus strains were isolated from collected mosquito pools during April, May and June; whereas JE virus strain was not yet isolated from collected mosquito pool in July. Thus, in order to control JE disease, it is necessary to control JE vectors in April, May and June.

Detection of Japanese encephalitis frequency in the pig population in Ha Nam province by GAC-ELISA

Background: Mosquitoes and pigs play important roles in maintaining and increasing the Japanese Encephalitis (JE) virus in nature and which is then transmitted to humans. Thus, surveillance of the JE infection frequency in the pig population may predict the human JE cases. \r\n', u'Objectives: The study aimed to determine IgG antibody against the JE virus in the pig population in Hanam province \r\n', u'Subjects and methods: The study included 1791 pig serum samples collected from 3 districts of Hanam province from Apr 2006 to Mar 2007. GAC-ELISA technique was used to determine the JE virus infection in the swine population.\r\n', u'Results: The average positive rate in pig population was 34.9 % (626/1791); with the highest frequency occurring in the summer (37.7%- 84.0 %), co-incident with the JE season in Northern Vietnam. On the contrary, in winter JE case are rare, frequency of IgG antibody against JE virus in the swine population was low, ranging from 9.2% to 22.0.%. \r\n', u'Conclusions: These results have shown the ecologically close relationship between the amplification of the JE virus in the swine population, vector and JE cases in northern Vietnam. \r\n', u'

Detection of IgM anti Japanese Encephalitis (JE) virus by antigen genotype 1 & genotype 3

Background: Recently Japanese Encephalitis (JE) virus type 1 has surfaced and is co-circulated with JE virus type 3 in the northern areas of Viet Nam, so a sensitivity of JE viral antigen genotype 3 to detect IgM is required. Objectives: To compare the sensitivity of JE viral antigen genotype 1 and 3 to detect IgM against the JE virus. Materials and method: 783 cerebrospinal fluid and serum samples from viral encephalitis cases from 1999-2005 were collected and examined by MAC-ELISA for JE viral antigen genotype 1 and 3. Results: The agreement on the diagnosis of these kinds of antigen was 99.7% and the sensitivity of JE viral antigen genotype 3 was higher than that of genotype 1. Thus, JE viral antigen genotype 3 could be considered as the selected antigen for JE diagnosis in Viet Nam. IgM titer determined by JE viral antigen genotype 1 was higher than that of genotype 3 in 2003 and 2005 and lower in 1999, 2000, 2001, 2002 and 2004. Conclusion: The dominant phenomenon of JE viral genotypes differing over the years might be due to the interaction of the virus and its vectors. Further study is required to clarify this observation.

The study on vertical transmision of Nam Dinh Virus and Coltivirus group B from Culex quinque fasciatus in Can Tho Province

Background:\r\n', u'There are two virus known as Nam Dinh Virus, and Colti group B be found in Viet Nam. These viruses have appeared in the South, the Middle and the Highland. They haven\u2019t been reported in the Southern provinces and Can Thoas well. \r\n', u'Objectives: \r\n', u'To identify the circulation of Nam Dinh virus strain, and coltivirus group B strain in Can Tho, Southern Viet Nam, and their existence in nature.\r\n', u'Subjects and method: \r\n', u'Thirty-four mosquito samples (7, 453 individual mosquitoes) from Culex quinque faciatus and Culex pseudovishnui were collected in Can Tho provice, southern Vietnam 2005.\r\n', u'Isolatingviruses on Aedes albopictuc clone C6/36, Vero cells, and using PT- PCR and ELISA Sandwich for identification. \r\n', u'Results:\r\n', u'2 Nam Dinh virus strains, 2 coltivirus group B strains and 1 flavivirus strain (insect flavivirus) were isolated from Culex quinque faciatus, and no virus was isolated from Culex pseudovishnui.\r\n', u'Conclusion: \r\n', u'The identification of the transmission of Nam dinh Virus, and coltivirus group B in Can Tho province by isolating virus from Culex quinque faciatus has shown the evidence for natural vertical transmission of these viruses.\r\n', u'

Emerging a member of reoviridae family associated with acute encephalitis syndrome in Gia Lai province, 2005

Background: In recent years, some arbo viruses which causes acute encephalitis syndrome (AES) have been identified in serveral countries in the world such as Chandipura virus belonging to Rhabdoviridae family in India, Banna virus belonging to Reoviridae family in China. In Vietnam, apart from Japanese Encephalitis Virus which is considered as main cause of AES, there are a few intestinal viruses like Herpes symplex virus type 1 and 4 and Nam Dinh virus considering other causes of AES. Objective: To identify the hyppothesis that one virus strain parasitizing in mosquito in Gia Lai province causes AES in order to provide more information about virus strains which cause AES in Vietnam. Subjects and method: Aedes albopictus cell line clone C6/36 was used for the isolation of virus in 43 cerebrospinal fluid samples of patients who were treated in Gia Lai hospital, from January/2005 to July/2005. Result and Conclusion: One virus strain from a 3-year old girl in Gia Lai province was isolated in 2005. The virus coded 05VN225 has the morphology similar to other viruses belonging to Reoviridea family.The nucleic acid sequence of the virus was checked with specific primers of alphavirus and flavirus groups, Nam Dinh virus and Conti virus group B (reovirus) of the Reoviridae. The positive result was confirmed with reovirus primers. This member of the Reoviridae family was isolated from acute encephalitis syndrome in Vietnam in 2005. Further study on pathology of the virus is very necessary.