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.
Japanese Encephalitis ; antigen

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'
Virus ; Japanese Encephalitis ; genotype 1 ; E gene.

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'
Japanese encephalitis ; pig population ; GAC-ELISA.

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.
IgM antibody ; ELISA diagnostic kit ; Japanese encephalitis virus

Background: Japanese Encephalitis (JE) is common in the plains and mountainous areas in Asia \u2013 Pacific. Japanese encephalitis vaccine shows effectiveness in protecting children from JE in some countries such as Japan and Korea. Objective: To evaluate the efficacy of Japanese Encephalitis (JE) vaccination in Thai Binh province during 2003-2007. Subject and Method: Prospective, retrospective and sero-epidemiological methods were carried out on 329 samples collected from viral encephalitis patients and tested by JE MAC-ELISA, the positive average was 41.6% (137/329). Result: It had dramatically dropped from 85.2% in 2003 to 8.5 % in 2007 related to the rate of JE vaccination for children from 1 to 5 years old increasing from 49 % in 2003 to 77 % in 2007. Most of JE confirmed cases were un-vaccinated. Conclusion: JE etiology cause viral encephalitis in children in Thai Binh province was reduced thanks to JE vaccination in EPI program for 1 to 5 year old children. But more than 96% (131/136) of viral encephalitis in 15 years old upward was unknown etiology, the need for further study of the etiology cause viral encephalitis in adults.
Japanese encephalitis ; virus encephalitis ; MAC-ELISA ; Vaccine

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.

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'
Viruses ; Coltivirus ; Flavivirus ; Arboviruses ; Culex ;

Objective To characterize viral co-infections among representative hospitalized measles cases during the 2014 Hanoi outbreak. Methods Throat swabs were collected from 54 pediatric patients with confirmed measles, and molecular diagnostics performed for 10 additional viral respiratory pathogens (Influenza A/H1N1pdm09; A/H3N2 and influenza B; Parainfluenza 1, 2, 3; Respiratory Synctial Virus, RSV; human Metapneumovirus, hMPV; Adenovirus and Picornavirus). Results Twenty-one cases (38.9%) showed evidence of infection with other respiratory viruses: 15 samples contained measles plus one additional virus, and 6 samples contained measles plus 2 additional viruses. Adenovirus was detected as a predominant cause of co-infections (13 cases; 24.1%), followed by RSV (6 cases; 11.1%), A/H1N1pdm09 (3 cases; 5.6%), PIV3 (3 cases; 3.7%), Rhinovirus (3 cases; 3.7%) and hMPV (1 case; 1.96%). Conclusions Viral co-infections identified from pediatric measles cases may have contributed to increased disease severity and high rate of fatal outcomes. Optimal treatment of measles cases may require control of multiple viral respiratory pathogens.