Ashok Chauhan, PhD.
Adjunct Faculty (Neuro-virology)
Associate Professor in Pathology, Microbiology & Immunology
PhD: Post Graduate Institute of Medical Research and Education, India (1989-1993)
Post Doctoral training: International Center for Genetic Engineering and Biotechnology, Italy (1996-1998); Karolinska Institute, Sweden (1998-2000); Faculty: The Johns Hopkins School of Medicine (2003-2007)

Research Focus:

Dr. Chauhan specializes in molecular neuro-virology and his research focuses on understanding viral replication and neuropathogenesis of RNA viruses including retroviruses such as HIV. HIV is a retrovirus having RNA and DNA phases in viral life cycle. The HIV is neuroinvasive and produces brain infection which leads to cognitive impairment, motor dysfunction and finally severe form of disease known as HIV- associated-dementia in 15-20 percent of untreated cases. My lab is specifically interested in HIV-1 replication in PBMCs and neuro-glial cells particularly viral-persistence and low level of viral transcription in brain and its impact on dysregulation of astrocytes and neuronal functions through inflammatory molecules. Using gene-microarray and protein-array we have picked up cellular genes dysregulated by HIV-Tat protein and are further exploring their functions in relation to neuronal apoptosis and impairment of innate immune system genes in astrocytes and PBMCs. My laboratory has developed various expression vectors and transgenic cells to study HIV in in-vitro cell systems. We have observed that Tat protein localizes permanently in the nucleus and nucleolus and therefore, is implicated in cellular gene regulation apart from HIV transcription. Second interest is hepatitis C virus (HCV) and encephalopathy. The HCV is an RNA virus, which produces chronic infection in humans and leads to acute hepatitis, cirrhosis, hepatic cellular carcinoma and hepatic encephalopathy. The exact mechanism of encephalopathy is not yet known. We are investigating extra hepatic cell population as a target of HCV in relation to neuropathogenesis in particular astrocytes which are brain resident cells expressing HCV receptor CD81. Third interest is gene transfer and siRNA delivery to brain and PBMCs in-vitro and in-vivo using small cell penetrating peptides (CPPs) in combination with siRNA and viral vector DNA such as lentiviral, adenoviral and AAV vectors. The major impediment in gene delivery to CNS is blood brain barrier (BBB) and we are exploring chimeric combinations of different peptides in particular RNA binding domain of HIV Tat protein with cell penetrating domains for siRNA delivery.

Selected publications

• Ashok Chauhan, Sven Hahn, Suzanne Gartner, Carlos A. Pardo- Villamizar, Senthil kumar Netisan, Justin McArthur and Avindra Nath Molecular programming of Endothelin-1 in HIV infected Brain: Role of Tat in upregulation and its inhibition by Statins. FASEB J 21: 777-789, 2007.
• Ashok Chauhan, Akshay Tikoo, Arvinder Kaur and Mahavir Singh. The Taming of the Cell Penetrating Domain of the HIV Tat: Myths and Realities. J Controlled Release 117(2): 148-62, 2007.
• Johan Brask, Ashok Chauhan, R.H. Hill, H-G. Ljunggren and Krister Kristensson. The effects on synaptic activity by influenza A/WSN/33 viral proteins NS1 and NP in hippocampal cultures. J. NeuroVirology, 11: 395- 402. 2005.
• Bruce-Keller AJ, Chauhan A, Dimayuga, FO, Gee, J Keller, JN, Nath A. Synaptic transport of HIV-Tat protein causes neurotoxicity and gliosis in rat brain. J. Neuroscience, 23(23): 8417 - 8422, 2003.
• Ashok Chauhan, J. Turchan, C. Pocernich, A. Bruce-Keller, S. Roth, D.A. Butterfield, E.O. Major, A. Nath. Intracellular HIV Tat expression in astrocytes promotes astrocyte survival but induces neurotoxicity. J Biol Chem 2003; 278:13512-19. Kevin Rostasy , Christophe Egles, Ashok Chauhan , Michelle Kneissl , Padmanabhan Bahrani , Constantin Yiannoutsos , Dale D. Hunter ., Avindra Nath , John C Hedreen, Bradford A. Navia. SDF-1 , the main ligand for CXCR4, is expressed predominantly in astrocytes as well as neurons in patients with the AIDS dementia complex (ADC). Journal of Neuro-pathology and Experimental Neurology, 62(6): 617-626, 2003.
• Ashok Chauhan, S. Jameel, J.B. Dilawari, Y.K. Chawla, U.Kaur, and N.K.Ganguly. Hepatitis E transmission in volunteer. Lancet (1993) 341:149-50.
• Ashok Chauhan, J.B.Dilawari, S.Jameel, U.Kaur, Y.K.Chawla, M.L.Sharma and N.K.Ganguly. Comman etiological agent for epidemic and sporadic nonA, nonB hepatitis. Lancet (1992)339:1509-10.