Kattur Venkatachalam Ashok Raj

@psgcas.ac.in

Senior Research Fellow, Department of Microbiology
PSG College of Arts and Science

Kattur Venkatachalam Ashok Raj


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https://researchid.co/kvashokraj

RESEARCH INTERESTS

Vaccines and Antibodies
4

Scopus Publications

88

Scholar Citations

5

Scholar h-index

3

Scholar i10-index

Scopus Publications

  • Amino acid substitutions improve the immunogenicity of H7N7HA protein and protect mice against lethal H7N7 viral challenge
    Subaschandrabose Rajesh kumar, Mookkan Prabakaran, Kattur Venkatachalam Ashok raj, Fang He, Jimmy Kwang
    Plos One, 2015
    Avian influenza A H7N7/NL/219/03 virus creates a serious pandemic threat to human health because it can transmit directly from domestic poultry to humans and from human to human. Our previous vaccine study reported that mice when immunized intranasally (i.n) with live Bac-HA were protected from lethal H7N7/NL/219/03 challenge, whereas incomplete protection was obtained when administered subcutaneously (s.c) due to the fact that H7N7 is a poor inducer of neutralizing antibodies. Interestingly, our recent vaccine studies reported that mice when vaccinated subcutaneously with Bac-HA (H7N9) was protected against both H7N9 (A/Sh2/2013) and H7N7 virus challenge. HA1 region of both H7N7 and H7N9 viruses are differ at 15 amino acid positions. Among those, we selected three amino acid positions (T143, T198 and I211) in HA1 region of H7N7. These amino acids are located within or near the receptor binding site. Following the selection, we substituted the amino acid at these three positions with amino acids found on H7N9HA wild-type. In this study, we evaluate the impact of amino acid substitutions in the H7N7 HA-protein on the immunogenicity. We generated six mutant constructs from wild-type influenza H7N7HA cDNA by site directed mutagenesis, and individually expressed mutant HA protein on the surface of baculovirus (Bac-HAm) and compared their protective efficacy of the vaccines with Bac-H7N7HA wild-type (Bac-HA) by lethal H7N7 viral challenge in a mouse model. We found that mice immunized subcutaneously with Bac-HAm constructs T143A or T198A-I211V or I211V-T143A serum showed significantly higher hemagglutination inhibition and neutralization titer against H7N7 and H7N9 viruses when compared to Bac-HA vaccinated mice groups. We also observed low level of lung viral titer, negligible weight loss and complete protection against lethal H7N7 viral challenge. Our results indicated that amino acid substitution at position 143 or 211 improve immunogenicity of H7N7HA vaccine against H7N7/NL/219/03 virus.
  • Concentration and purification of enterovirus 71 using a weak anion-exchange monolithic column
    Ashok Raj Kattur Venkatachalam, Milene Szyporta, Tanja Kristin Kiener, Premanand Balraj, Jimmy Kwang
    Virology Journal, 2014
    BACKGROUND: Enterovirus 71 (EV-71) is a neurotropic virus causing Hand, Foot and Mouth Disease (HFMD) in infants and children under the age of five. It is a major concern for public health issues across Asia-Pacific region. The most effective way to control the disease caused by EV-71 is by vaccination thus a novel vaccine is urgently needed. Inactivated EV-71 induces a strong, virus-neutralizing antibody response in animal models, protecting them against a lethal EV-71 challenge and it has been shown to elicit cross-neutralizing antibodies in human trials. Hence, the large-scale production of purified EV-71 is required for vaccine development, diagnosis and clinical trials. METHODS: CIM® Monolith columns are single-piece columns made up of poly(glycidyl methacrylate co-ethylene dimethacrylate) as support matrix. They are designed as porous channels rather than beads with different chemistries for different requirements. As monolithic columns have a high binding capacity, flow rate and resolution, a CIM® DEAE-8f tube monolithic column was selected for purification in this study. The EV-71 infected Rhabdomyosarcoma (RD) cell supernatant was concentrated using 8% PEG 8000 in the presence of 400 mM sodium chloride. The concentrated virus was purified by weak anion exchange column using 50 mM HEPES + 1 M sodium chloride as elution buffer. RESULTS: Highly pure viral particles were obtained at a concentration of 350 mM sodium chloride as confirmed by SDS-PAGE and electron microscopy. Presence of viral proteins VP1, VP2 and VP3 was validated by western blotting. The overall process achieved a recovery of 55%. CONCLUSIONS: EV-71 viral particles of up to 95% purity can be recovered by a single step ion-exchange chromatography using CIM-DEAE monolithic columns and 1 M sodium chloride as elution buffer. Moreover, this method is scalable to purify several litres of virus-containing supernatant, using industrial monolithic columns with a capacity of up to 8 L such as CIM® cGMP tube monolithic columns.
  • Cross-protective efficacy of baculovirus displayed hemagglutinin against highly pathogenic influenza H7 subtypes
    Mookkan Prabakaran, Subaschandrabose Rajesh Kumar, Kattur Venkatachalam Ashok Raj, Xiapeng Wu, Fang He, JiYong Zhou, Jimmy Kwang
    Antiviral Research, 2014
  • Development of A Sensitive and Specific Epitope-Blocking ELISA for Universal Detection of Antibodies to Human Enterovirus 71 Strains
    Fang He, Tanja K. Kiener, Xiao Fang Lim, Yunrui Tan, Kattur Venkatachalam Ashok Raj, Manli Tang, Vincent T. K. Chow, Qingfeng Chen, Jimmy Kwang
    Plos One, 2013
    Background Human Enterovirus 71 (EV71) is a common cause of hand, foot and mouth disease (HFMD) in young children. It is often associated with severe neurological diseases and mortalities in recent outbreaks across the Asia Pacific region. Currently, there is no efficient universal antibody test available to detect EV71 infections. Methodology/Principal Finding In the present study, an epitope-blocking ELISA was developed to detect specific antibodies to human EV71 viruses in human or animal sera. The assay relies on a novel monoclonal antibody (Mab 1C6) that specifically binds to capsid proteins in whole EV71 viruses without any cross reaction to any EV71 capsid protein expressed alone. The sensitivity and specificity of the epitope-blocking ELISA for EV71 was evaluated and compared to microneutralization using immunized animal sera to multiple virus genotypes of EV71 and coxsackieviruses. Further, 200 serum sample from human individuals who were potentially infected with EV71 viruses were tested in both the blocking ELISA and microneutralization. Results indicated that antibodies to EV71 were readily detected in immunized animals or human sera by the epitope blocking ELISA whereas specimens with antibodies to other enteroviruses yielded negative results. This assay is not only simpler to perform but also shows higher sensitivity and specificity as compared to microneutralization. Conclusion The epitope-blocking ELISA based on a unique Mab 1C6 provided highly sensitive and 100% specific detection of antibodies to human EV71 viruses in human sera.

RECENT SCHOLAR PUBLICATIONS

  • Novel CRT2 peptide inhibits tumor growth and angiogenesis in colorectal cancer HT-116 cell lines via PI3K/ERK signaling pathway
    D Yogananthan, ARK Venkatachalam, R Muthiah
    Bangladesh Journal of Pharmacology 20 (3), 89-100 , 2025
    2025
  • Gold nanoparticle-based electrochemical immunosensor for the detection of Russell’s viper venom using IgY antibodies
    S Janani, A Choraria, KVA Raj, S Rajeswari, R Sivasubramanian, ...
    Microchemical Journal 212, 113247 , 2025
    2025
    Citations: 1
  • Production and characterization of bioflocculant produced by Bacillus subtilis OL818309 and its flocculating effect on harmful algae
    A Jayaprakash, S Revathy, KV Ashok Raj, EM Rajesh
    Research Journal of Biotechnology 18 (2), 72-85 , 2023
    2023
    Citations: 7
  • A Selectivity of Super-Short Peptide Morphed Hydrophilic and Hydrophobic Domains to Improve Anti-Cancer Efficacy
    Y Dhanapal, KV Ashok Raj, M Ramanathan
    European Chemical Bulletin 12 (2), 5381-5388 , 2023
    2023
  • Microbial flocculants as an excellent alternative to synthetic flocculants for industrial application: A comprehensive review
    A Jayaprakash, KV Ashok Raj, S Revathy, EM Rajesh
    Asia Pacific Journal of Molecular Biology and Biotechnology 30 (4), 79-97 , 2022
    2022
    Citations: 5
  • Amino Acid Substitutions Improve the Immunogenicity of H7N7HA Protein and Protect Mice against Lethal H7N7 Viral Challenge
    S Rajesh Kumar, M Prabakaran, KV Ashok Raj, H Fang, J Kwang
    PLoS one 10 (6), e0128940 , 2015
    2015
    Citations: 9
  • Concentration and purification of enterovirus 71 using a weak anion-exchange monolithic column
    KV Ashok Raj, S Milene, K Tanja Kristin, B Premanand, J Kwang
    Virology journal 11, 1-8 , 2014
    2014
    Citations: 40
  • Cross-protective efficacy of baculovirus displayed hemagglutinin against highly pathogenic influenza H7 subtypes
    M Prabakaran, S Rajesh Kumar, KV Ashok Raj, X Wu, F He, JY Zhou, ...
    Antiviral research 109, 149-159 , 2014
    2014
    Citations: 16
  • Development of a sensitive and specific epitope-blocking ELISA for universal detection of antibodies to human enterovirus 71 strains
    F He, K Tanja Kristin, L Xiao Fang, T Yunrui, KV Ashok Raj, T Manli, ...
    PLoS one 8 (1), e55517 , 2013
    2013
    Citations: 10

MOST CITED SCHOLAR PUBLICATIONS

  • Concentration and purification of enterovirus 71 using a weak anion-exchange monolithic column
    KV Ashok Raj, S Milene, K Tanja Kristin, B Premanand, J Kwang
    Virology journal 11, 1-8 , 2014
    2014
    Citations: 40
  • Cross-protective efficacy of baculovirus displayed hemagglutinin against highly pathogenic influenza H7 subtypes
    M Prabakaran, S Rajesh Kumar, KV Ashok Raj, X Wu, F He, JY Zhou, ...
    Antiviral research 109, 149-159 , 2014
    2014
    Citations: 16
  • Development of a sensitive and specific epitope-blocking ELISA for universal detection of antibodies to human enterovirus 71 strains
    F He, K Tanja Kristin, L Xiao Fang, T Yunrui, KV Ashok Raj, T Manli, ...
    PLoS one 8 (1), e55517 , 2013
    2013
    Citations: 10
  • Amino Acid Substitutions Improve the Immunogenicity of H7N7HA Protein and Protect Mice against Lethal H7N7 Viral Challenge
    S Rajesh Kumar, M Prabakaran, KV Ashok Raj, H Fang, J Kwang
    PLoS one 10 (6), e0128940 , 2015
    2015
    Citations: 9
  • Production and characterization of bioflocculant produced by Bacillus subtilis OL818309 and its flocculating effect on harmful algae
    A Jayaprakash, S Revathy, KV Ashok Raj, EM Rajesh
    Research Journal of Biotechnology 18 (2), 72-85 , 2023
    2023
    Citations: 7
  • Microbial flocculants as an excellent alternative to synthetic flocculants for industrial application: A comprehensive review
    A Jayaprakash, KV Ashok Raj, S Revathy, EM Rajesh
    Asia Pacific Journal of Molecular Biology and Biotechnology 30 (4), 79-97 , 2022
    2022
    Citations: 5
  • Gold nanoparticle-based electrochemical immunosensor for the detection of Russell’s viper venom using IgY antibodies
    S Janani, A Choraria, KVA Raj, S Rajeswari, R Sivasubramanian, ...
    Microchemical Journal 212, 113247 , 2025
    2025
    Citations: 1
  • Novel CRT2 peptide inhibits tumor growth and angiogenesis in colorectal cancer HT-116 cell lines via PI3K/ERK signaling pathway
    D Yogananthan, ARK Venkatachalam, R Muthiah
    Bangladesh Journal of Pharmacology 20 (3), 89-100 , 2025
    2025
  • A Selectivity of Super-Short Peptide Morphed Hydrophilic and Hydrophobic Domains to Improve Anti-Cancer Efficacy
    Y Dhanapal, KV Ashok Raj, M Ramanathan
    European Chemical Bulletin 12 (2), 5381-5388 , 2023
    2023