ANNUAL REPORT - Department of Biotechnology

initiated for the development of dengue diagnostics
and vaccines using approaches that could generate
propriety leads.
A group at NIMHANS, Bangalore has initiated the
development of dengue specific monoclonal
antibodies for an assay towards development of a
serological kit. Efforts are being made to replace the
mouse brain antigens.
Work has been initiated to make non-replicating subunit
tetra-valent dengue vaccine based on a critical
domain of the major dengue structural envelope
protein that is involved in host receptor recognition
and in the induction of robust protective immunity.
The prototype strains of each of the four DEN
serotypes have been incorporated into Pichia
pastoris and a novel 'monovalent' and 'tetravalent'
dengue antigen genes encoding the serotypespecific
Pichia shuttle vector created. Efforts are
now being made to express the recombinant
domains III of all four dengue (DEN) virus serotypes
(tetravalent) in P. pastoris, which can grow in simple
defined medium and produce functional
recombinant proteins in gram quantities per liter of
culture. The “Proof of Principle” has been
established to use tetravalent domain III based
vaccine candidate in animal models. The same is
being taken up on a fast track with an industrial
partner i.e. Bharat Biotech International Ltd.,
Hyderabad.
Parallely, the scientists at ICGEB are working on a
hypothesis that a single tetravalent DNA virus-based
vaccine may provide a means of circumventing viral
interference.
Japanese Encephalitis
The Department continues to support translation
research towards improvement of current vaccines;
and development of newer approaches for the JE
vaccine especially due to recurrent epidemics as
also serious adverse events reported by the
introduction of a Chinese vaccine. The project on the
development of a tissue culture based vaccine
(Indian strain adapted to Vero cells) carried out NII,
105
New Delhi progressed well. Vero cell-derived,
inactivated JEV vaccine was successfully
transferred to M/s Panacea Biotech. This
technology has since been validated, optimized
using WHO-supplied Vero cells, and upscale to the
fermenter level. A GMP facility for JE vaccine
production is now in place at Panacea. Several
reagents and quality assurance methods related to
the vaccine production process have been
developed and validated. However, methods for
virus purification are being optimized for which
Panacea, Delhi has procured a continuous-flow
zonal ultracentrifuge which is likely to be installed by
February 2007. The centrifuge will then be used for
the large scale virus purification process
development after which the material for pre-clinical
toxicology and phase I trials would be produced.
The approach using Adeno based vectors as a
backbone for JE DNA vaccine has shown good
results. The “Proof of concept” in animal model has
been established for using Adeno 5 as backbone for
relevant DNA in JE infection. It was suggested to be
seen whether there are pre-existing antibodies to
Adeno 5 in infant/children that may hamper the
protective response. In a study carried out, results
show that children below 12 months age possess
significantly lower anti-adenovirus antibodies as well
as Ad5-neutralising antibodies, after which there is a
marked increase in antibody titers. The findings are
consistent with the reports from other parts of the
world. Although alternate strategies are being
explored to overcome the pre-existing Ad5 immunity
in humans, the results, together with earlier finding
that low levels of Ad5 antibodies do not interfere with
the recombinant adenovirus vaccine uptake in mice
suggest that Ad5-based vaccines or other
therapeutics may still be effective if administered
during the 6-12 months age bracket. This may pave a
path for Adeno- based JE vaccine for that age group.
The study on molecular mechanisms of
microglia/macrophages mediated neuron-
inflammation in Japanese Encephalitis carried out at
NBRC, Manesar has demonstrated that microglial
activation may be an important contributory factor in
Research and Development