1Division of Virology, Defence R & D Establishment (DRDE), Jhansi Road, Gwalior-474002, India
2Departments of Microbiology, Nizams Institute of Medical Sciences (NIMS), Hyderabad-500082, India.
Abstracts of the papers presented at the International Conference of Indian Virological Society on “Emerging and Re-emerging viral Diseases of the Tropics and Subtropics” at Indian Agricultural Research Institute, New Delhi, India, December 11–14, 2007.
Dengue (DEN) and Chikungunya (CHIK) are emerging as important mosquito borne viral infections in most parts of the tropics. Both these infections produce similar clinical symptoms, and are endemic in same geographical area, warranting an urgent need for the differential diagnosis. So far no single assay is reported for differential diagnosis of these two infections. In this study, we report the development and validation of a one step duplex reverse transcription-polymerase chain reaction (D-RT-PCR) assay by targeting C-prM gene junction and E1 gene of DEN and CHIK virus respectively. The sensitivity of this assay was found to be better than conventional virus isolation and could detect as low as 100 copies of genomic RNA, which is equivalent to respective virus specific RT-PCR. The specificity of this assay was confirmed by including specimens from healthy individuals and closely related viruses from genus flaviviruses and alphaviruses. The evaluation was carried out with 560 clinical samples from dengue and chikungunya outbreaks in India. This assay could also able to detect dual infection of DEN and CHIK in five patients. The phylogenetic analysis based on the nucleotide sequencing of D-RT-PCR amplicon could precisely identify the genotypes of all the serotypes of DEN and CHIK viruses. These findings demonstrate the potential clinical and epidemiological application of D-RT-PCR for rapid sensitive detection, differentiation and genotyping of DEN and CHIK viruses in clinical samples.
