Research Groups
Mammalian Biology: Recombinant Gene Products
Research Interests and Description
Principal Investigator: S. Swaminathan, PhD
Group Leader: Navin Khanna
Research Interests
Dengue. Adenovirus. Dengue reporter viruses. RNAi.
Description of Research
Reporter Dengue viruses
There is renewed interest in the dengue field in developing non-replicating subunit vaccines. At present, the many different VLP-based dengue vaccine candidates being developed in the Group are being assessed using the Plaque Reduction Neutralization Test (PRNT) - the gold standard assay to measure the neutralizing antibody titers. This assay, which is designed to measure residual infectivity of dengue viruses in response to the presence of neutralizing antibodies is labour-intensive, time-consuming and has very limited sample-handling capacity. In order to relieve the bottleneck imposed by PRNT, we are exploring the possibility of creating reporter dengue viruses encoding the green fluorescent protein or firefly luciferase. Our expectation is that the availability of such reporter dengue viruses would make the determination of neutralizing antibody titers amenable to a rapid and high throughput format with large sample handling capacity. To this end, we are working in collaboration with Prof. Vapalahti at the University of Helsinki, to develop sub-genomic flaviviral reporter replicons lacking the structural genes. We have created a stable cell line, which expresses dengue virus type 2 structural proteins to permit packaging of a dengue type 2 reporter replicon. Work is underway to construct a vector encoding a dengue type 2 reporter replicon.
RNAi to attenuate dengue virus replication
The plus sense RNA genome of dengue virus, which contains a single open reading frame, doubles as the template for both translation and replication. Targeting this RNA for degradation through RNAi offers one potential approach to curbing dengue replication in infected cells. We have used a panel of small hairpin (sh) RNA-encoding plasmid constructs targeting several sites in the non-coding regions of the dengue virus genome to identify shRNAs against conserved target sequences, capable of knocking down multiple dengue serotypes. We have created an adenoviral vector to deliver one of these shRNAs into infected cells. Using this shRNA-encoding adenoviral vector, we have been able to observe knockdown of all four dengue virus serotypes based on quantitative analyses of genomic RNA levels, viral antigen secretion and plaque assays.
Recent Publications
Batra, G., Nemani, S.K., Tyagi, P., Swaminathan, S., Khanna, N. 2011. Evaluation of envelope domain III-based single chimeric tetravalent antigen and monovalent antigen mixtures for the detection of anti-dengue antibodies in human sera. BMC Infect Dis 11, 64 PubMed link
Talha, S.M., Salminen, T., Swaminathan, S., Soukka, T., Pettersson, K., Khanna N. 2011. A highly sensitive and specific time resolved fluorometric bridge assay for antibodies to HIV-1 and -2. J Virol Methods 173, 24-30 PubMed link
Batra, G., Gurramkonda, C., Nemani, S.K., Jain, S.K., Swaminathan, S., Khanna, N. 2010. Optimization of conditions for secretion of dengue virus type 2 envelope domain III using Pichia pastoris. J Biosci Bioeng 110, 408-14 PubMed link
Pilankatta, R., Chawla, T., Khanna, N., Swaminathan, S. 2010. The prevalence of antibodies to adenovirus serotype 5 in adult Indian population and implications for adenovirus vector vaccines. J Med Virol 82, 407-414 PubMed link
Swaminathan, S., Batra, G., Khanna, N. 2010. Dengue vaccines: state of the art. Expert Opin Therap Pat 20, 819-835 PubMed link
Swaminathan, S., Khanna, N. 2010. Dengue vaccine-current progress and challenges. Curr Sci 98, 369-378
