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OBJECTIVE@#To identify immunological evidence of Zika virus transmission in Thailand.@*METHODS@#To undertake a preliminary serosurvey of possible exposure to Zika virus, 21 serum samples from cohort of acute undifferentiated fever patients were examined for immunoreactivity to Zika, Dengue, Japanese encephalitis and Chikungunya envelope antigens by Western blot analysis.@*RESULTS@#Twenty of the 21 serum samples showed immunoreactivity to at least one of the antigens, with seven samples showing immunoreactivity to all antigens. Of particular note, two serum samples showed immunoreactivity only to Zika envelope antigen, with no immunoreactivity to other envelope antigens.@*CONCLUSIONS@#This study presents the first evidence of Zika virus transmission in Thailand, although as yet the relationship between transmission and possible cases of Zika fever in Thailand requires further investigation.
RESUMEN
Objective: To identify immunological evidence of Zika virus transmission in Thailand. Methods: To undertake a preliminary serosurvey of possible exposure to Zika virus, 21 serum samples from cohort of acute undifferentiated fever patients were examined for immunoreactivity to Zika, Dengue, Japanese encephalitis and Chikungunya envelope antigens by Western blot analysis. Results: Twenty of the 21 serum samples showed immunoreactivity to at least one of the antigens, with seven samples showing immunoreactivity to all antigens. Of particular note, two serum samples showed immunoreactivity only to Zika envelope antigen, with no immunoreactivity to other envelope antigens. Conclusions: This study presents the first evidence of Zika virus transmission in Thailand, although as yet the relationship between transmission and possible cases of Zika fever in Thailand requires further investigation.
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Chikungunya (CHIKV) is an arboviral disease transmitted by Aedes mosquitoes. The recent resurgence of CHIKV in Thailand is a matter of great public health concern. Despite the fact that CHIKV resurgence is associated with epidemic, no approved licensed vaccine is currently available. A formalin inactivated CHIKV vaccine revealed absence of untoward reactions or side effects and the acceptable immunogenic response in volunteers attested to the safety and immunogenicity of this vaccine. An attenuated CHIKV virus clone was developed for production of a live vaccine for human use. Vaccine (pilot lot production) elicited safety and immunogenicity of this vaccine in phase I and II studies in healthy adult volunteers. This live vaccine was safe, produced well tolerated side effects, and was highly immunogenic. Among the various vaccine approached, an attenuated live virus to be chosen should contain the gene for a broadly cross reacting protective antigen.
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The discovery at the University of Hawaii that dengue viruses could be propagated serially in Primary Dog Kidney (PDK) cells offered an initial step for development of live dengue vaccines. At Mahidol University, dengue 1, 2 and 4 viruses could successfully propagate in PDK cells, whereas dengue 3 virus could not and was to serially passaged in primary green monkey kidney (PGMK) cells. Certain biological attributes were used for selection of candidate dengue vaccine viruses. Progeny viruses in PDK and PGMK cells revealed progressive modification in phenotypic markers of all 4 dengue serotypes. Seven monovalent dengue vaccine candidates were selected and used in phase 1 clinical trials in flavivirus non-immune subjects. Monovalent dengue 1, 2 and 4 candidate vaccines were proved to be safe and immunogenic. These 3 acceptably attenuated dengue vaccines could be used for immunization in one injection resulted in strong neutralizing antibodies against dengue 1, 2 and 4 serotypes in all vaccines. This marked an important milestone in using products based on PDK cell passage. Using underattenuated dengue 3 progeny adapted in PGMK revealed viral interference in the tetravalent combination. After fixing the dengue 3 problem, opportunity of having an ideal tetravalent dengue vaccine with balanced immunogenicity is now opened.