# Mechanistic role of ns2 protein in evasion of innate immune response by alphaviruses

> **NIH NIH R01** · UNIVERSITY OF ALABAMA AT BIRMINGHAM · 2021 · $603,624

## Abstract

Alphaviruses are an important group of human and animal pathogens that are widely
distributed on all continents. Until recently, the importance of the Old World alphaviruses
in global human health was strongly underestimated. However, recent outbreaks of
chikungunya virus (CHIKV) in India, Italy, East Africa's coastal islands and most recently
on the Caribbean islands, South and Central America, Oceania have highlighted the risk
posed by this virus. Our previous studies have unambiguously demonstrated that the
Old World alphaviruses employ their nonstructural protein nsP2 to re-direct the cellular
transcription coupled repair pathway for degradation of the catalytic subunit of the DNA-
dependent RNA polymerase II, RPB1, and thus, to completely inhibit cellular
transcription. Within a few hours post infection, virus-induced transcriptional shutoff
makes the cells incapable of initiating an antiviral response and leads to development of
cytopathic effect. Thus, the Old World alphavirus nsP2 is the major determinant of
pathogenesis at the molecular and cellular levels. We have also demonstrated that the
transcription inhibitory functions of nsP2 are determined not by its proteolytic activity, but
by the ability of this protein to function as a helicase, and by its S-adenosyl-L-
methionine-dependent RNA methyltransferase-like (SAM-like) domain. Two specific
aims of the proposed research plan are focused on i) mechanistic understanding of the
nsP2 helicase domain function in stalling cellular DNA-dependent RNA polymerase II
and ii) on identification of cellular proteins that interact with the SAM-like domain of
nsP2. We will also define the mechanistic role of the interactions of the latter domain in
transcription inhibition. In our preliminary studies, we have developed a set of CHIKV
variants with mutated nsP2, which are incapable of interfering with development of the
innate immune response to CHIKV replication. These irreversible mutations had no
detectable effect on the rates of CHIKV replication in cells defective in type I IFN
signaling, but are cleared from IFN-competent cells without development of cytopathic
effect. Therefore, in the third specific aim, we intend to assess the potential of these
nsP2 mutants to improve the safety of the currently available experimental vaccine
CHIKV 181/25.

## Key facts

- **NIH application ID:** 10165475
- **Project number:** 5R01AI133159-05
- **Recipient organization:** UNIVERSITY OF ALABAMA AT BIRMINGHAM
- **Principal Investigator:** ELENA I FROLOVA
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $603,624
- **Award type:** 5
- **Project period:** 2017-06-16 → 2023-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10165475

## Citation

> US National Institutes of Health, RePORTER application 10165475, Mechanistic role of ns2 protein in evasion of innate immune response by alphaviruses (5R01AI133159-05). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10165475. Licensed CC0.

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