Page 106 - Annual report 2021-22

Annual Report 2021-22 |

Vivek Rao

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Vivek Rao’s lab is focussed on developing host directed therapies against tuberculosis.

In an effort to identify FDA approved drugs to ameliorate the type I IFN response in TB infection, Vivek
Rao’s lab identified the anti-depressant drug Sertraline. His lab discovered that besides this, Sertraline
could synergize with anti-TB drugs to reduce the dose required to achieve bactericidal effects. They
found that Sertraline as an adjunct to standard HRZE (Isoniazid-Rifampicin-Pyrazinamide-Ethambutol)
regimen provides faster control of bacteria than the conventional 4 drug therapy from the infected
animal lungs. In order to understand the molecular basis for this potentiation, the cytokine profiles in
lungs of animals were analysed by Milliplex ELISA. Contrary to their expectations, there were no
significant differences in the levels of pro-inflammatory cytokines like TNFalpha, IFNgamma, IL6, IL1,
IL12 or IL2 in the lungs of mice administered standard antibiotics versus those administered sertraline
in addition to antibiotics. Because the potentiation of antibiotics was observed in cellular models of
infection, his group is currently using these to elucidate the host signalling pathways responsible for
sertraline mediated increase in antibiotic efficacy of infected macrophages.

Another modifier of the Type I IFN response to infection was identified by his group using RNAseq
analysis of Mtb infected macrophages. This was a mitochondrial localized enzyme named CMPK2. By
regulating the expression of CMPK2, a mitochondria resident kinase, macrophages can regulate the
extent of inflammatory response. His group has identified a novel regulatory link between
mitochondrial physiology and inflammation homeostasis of macrophages. Within the CMPK2 locus his
group identified a novel TLR4 signalling dependent non-coding RNA TILT. They identified this to be
induced in E. coli, Salmonella and Mycobacterium infection and upregulated in the blood of TB
patients.
BCG vaccination is one of the leading causes for early childhood protection against not only
tuberculosis but also several viral infections through a phenomenon called trained immunity. Given
its high safety profile, Vivek Rao’s group has been working on developing recombinant BCG based
vaccines against SARS-CoV2 infection. 4 genes of SARS COV2 were cloned and expressed in
mycobacteria M.smegmatis strains under the transcriptional control of the strong HSP60 promoter.
The expression of the genes were also expressed as fusion proteins with mycobacterial secretion
signals to secrete the proteins to the outside of mycobacteria. Expression of the individual antigens
were analyzed in Mycobacterium smegmatis immunoblotting with tag specific antibodies. The E, M,
and N transformants were not obtained and the S specific clones were checked. The antigen showed
non-specific cleavage in mycobacteria. Further only the RBD domain of SPIKE was cloned into the
vectors; RBD regions of clade 2, clade 4 and Delta virus were used for this study. After analysis of
expression, rBCG strains were developed. After confirmation of expression, the clones were used to
immunize mice. Through this work, his lab has developed new vectors for modular expression and
secretion of antigens in mycobacteria.

Circulating immune cells express signatures of disease state and the lab wants to use this information
of circulating immune cells in developing a blood-based signature for tuberculosis that will allow
differential diagnosis from silicosis. Stone cutting related professions have led to high rates of silicosis