Serological study of hantavirus in the rodent population of Nakhon Pathom and Nakhon Ratchasima Provinces Thailand.

A serological survey has been carried out to detect evidence of hantavirus infection in rodents from two provinces of Thailand. This study aimed to examine virus antibody in 354 rodents trapped among 6 different villages of Nakhon Pathom Province (February-March, 1998) and in 326 rodents trapped among 14 villages of Nakhon Ratchasima Province (August-October, 1998). Seroprevalence among rodents from Nakhon Pathom Province (2.3%), was mostly find in Rattus norvegicus (3.8%) and Bandicota indica (2.6%). In Nakhon Ratchasima Province seroprevalence (4.0%) was mostly in Bandicota indica (19.1%) and Rattus exulans (3.5%).

Preliminary study on potential circulation of arenaviruses in the rodent population of Nakhon Pathom Province, Thailand and their medical importance in an evoluting environment.

Preliminary serological investigations were prefered to detect evidence of arenavirus infection in rodents. The study examined virus antibody in 367 rodents trapped in 6 different geographical areas of Nakhon Pathom Province, Thailand from February-March, 1998. The overall seroprevalence among rodents was 13.3%, mostly in Bandicota savilei (35.7%) and Rattus norvegicus (31.5%). Between ecology, behavior and sex of the rodents, seroprevalence was not significantly different (p>0.05), however the seroprevalence found among different geographical areas of Nakhon Pathom Province were significantly different (p<0.0001).

Dengue-3 (16562) PGMK 33 vaccine: neurovirulence, viremia and immune responses in Macaca fascicularis.

Investigation of monkey neurovirulence of dengue-3 viruses (DEN-3, 16562) was undertaken to provide an evaluation of the relative safety of virus strain attenuated for potential use of live virus vaccine. Ten flavivirus-negative, cynomolgus monkeys (Macacafascicularis) were used in the test. The animals were inoculated intrathalamically, intraspinally and intramuscularly with DEN-3 PGMK 33 attenuated live virus vaccine (6 monkeys): parent virus (2) and control cell culture fluid (2). Blood samples were collected on days 0, 1, 2, 4, 6, 8, 10, 12 and 21 for virus isolation and days 0 and 21 or 22 for serologic testing. One monkey with DEN-3 (16562) PGMK 33 candidate vaccine had detectable viremia on day 10. By day 21, all recipients of PGMK 33 and both monkeys with DEN-3 parent virus developed serum neutralizing antibodies to DEN-3 titers ranged from 56-320. The monkeys showed no evidence of illness and none died of dengue infection. Histopathological examination of tissue collected on day 21 or 22 revealed only minimal neurovirulence lesions as scored by the routine grading system. No differences were observed between the DEN-3 parent and vaccine viruses and it is concluded that neither virus is neurovirulent for cynomolgus monkeys.