# Parvovirus B19 NS1 nickase-based high-throughput screening and structure study of the nickase

> **NIH NIH R21** · UNIVERSITY OF KANSAS MEDICAL CENTER · 2020 · $191,250

## Abstract

PROJECT SUMMARY
Human parvovirus B19 (B19V) is a pathogenic human parvovirus. Productive B19V infection is highly restricted
to human erythroid progenitor cells in the bone marrow or fetal liver and induces cell cycle arrest and cell death
of the infected cells, which results in a series of hematological disorders. In patients with a high demand for
erythrocyte production due to high levels of erythrocyte destruction (e.g., sickle cell disease patients), acute
B19V infection can cause transient aplastic crisis. In immunocompromised patients, persistent B19V infection
can manifest as pure red-cell aplasia. In the fetus, B19V infection can cause hydrops fetalis, a severe form of
anemia. Currently, there are neither vaccines nor anti-virals developed to prevent or treat B19V infection-
caused hematological disorders. B19V has a single-stranded DNA genome with two identical inverted terminal
repeats (ITRs) at the ends. We have identified the minimal viral DNA replication origin (Ori) of 67 nucleotides at
the ITRs, which contains binding domains of the viral large nonstructural protein NS1 and an NS1 nicking site.
B19V DNA replication proceeds according to the rolling-hairpin model of parvovirus DNA replication. NS1 nicks
the Ori at the nicking site by its N-terminal nickase domain, which is a specific enzymatic reaction during the
initiation of viral DNA replication. Our central hypothesis is that inhibition of NS1 nicking of the Ori prevents the
initiation of viral DNA replication, and therefore, inhibits virus replication. We have established a fluorophore-
based in vitro nicking assay using a single-stranded DNA probe spanning the nicking site and the NS1 nickase.
In the proposed research here, we aim, firstly, to establish the fluorophore-based nicking assay in a high
throughput format and to screen KU libraries of ~10,000 small molecule compounds for identification of leads
that inhibit the NS1 nicking activity in vitro. We will then examine the leads for inhibition of viral DNA replication
in B19V-permissive UT7/Epo-S1 cells transfected with a B19V replicative form genome and for antiviral activity
in B19V infection of ex vivo expanded human erythroid progenitor cells. Next, we aim to determine the
structure of the NS1 nickase, which will be used for structure-based rational design of antivirals in the future.
Our long-term goal is to develop effective anti-B19V drugs that can treat B19V infection-caused hematological
disorders.

## Key facts

- **NIH application ID:** 9882214
- **Project number:** 5R21AI144564-02
- **Recipient organization:** UNIVERSITY OF KANSAS MEDICAL CENTER
- **Principal Investigator:** Jianming Qiu
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $191,250
- **Award type:** 5
- **Project period:** 2019-03-01 → 2022-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9882214

## Citation

> US National Institutes of Health, RePORTER application 9882214, Parvovirus B19 NS1 nickase-based high-throughput screening and structure study of the nickase (5R21AI144564-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/9882214. Licensed CC0.

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