Comparison of sequences of E/NS1 gene junction of dengue type 3 virus following culture subpassage in C6/36 cells to study the possible occurrence of mutations.

The aim of this study was to determine whether mutations could occur in the dengue virus genome following three subpassages of the virus in a mosquito cell line. This was done because sources of virus isolates used for sequencing studies are usually maintained in cell lines rather than in patients' sera. Therefore it must be assured that no mutation occurred during the passaging. For this purpose, sequencing was carried out using the polymerase chain reaction (PCR) products of the envelope/non-structural protein 1 junction region (280 nucleotides) of dengue type 3 virus. Sequence data were compared between the virus from a patient's serum against the virus subpassaged three times in the C6/36 cell line. We found that the sequence data of the virus from serum was identical to the virus that was subpassaged three times in C6/36 cell line.

Cross-sectional serosurvey for Japanese encephalitis specific antibody from animal sera in Malaysia 1993.

Serum specimens were collected from 6 species of animals living in 9 states of Malaysia including Sabah, North Borneo in 1993. Antibodies against Japanese encephalitis (JE) virus in these sera were detected by means of hemagglutination-inhibition (HI) and neutralization (NT) tests. By HI test, 702 of 2,152 (32.6%) sera showed positive results. Higher positive rates were obtained by the NT test, in which 1,787 of 1,927 (92.7%) sera had antibodies against JE virus. All serum specimens with positive HI were confirmed as positive by the NT. Swine sera showed especially higher rates of antibody positive and higher antibody titers compared with other animals. These results suggest that JE infections are widely distributed among many animals of Malaysia, and pig is the most susceptible amplifier host for JE virus.