# Vaccines Against Ehrlichia and Anaplasma Species Infections

> **NIH NIH R01** · KANSAS STATE UNIVERSITY · 2022 · $622,465

## Abstract

PROJECT SUMMARY:
Rickettsial diseases caused by pathogens of the Anaplasmataceae family, including members of the genera
Ehrlichia and Anaplasma, have become a growing public health concern over the past three decades and are
a leading cause of tick-borne infections in humans throughout the USA and many parts of the world. The
diseases include the human monocytic and granulocytic ehrlichiosis caused by Ehrlichia chaffeensis and
Ehrlichia ewingii respectively, and the human granulocytic anaplasmosis resulting from Anaplasma
phagocytophilum infections. E. canis, first described as a canine pathogen, also causes infections in people.
Recently, another tick-borne pathogen, Ehrlichia muris subsp. eauclairensis, is also reported as causing
disease in people. These pathogens have evolved strategies to evade host immunity and cause persistent
infections. People with persistent infections are difficult to diagnose and pose risk to blood and organ
recipients. Through our recently established mutagenesis experiments, we created E. chaffeensis mutants
that contained insertions causing functional gene disruptions. An insertion mutation in the ECH_0660 gene
resulted in the pathogen's rapid clearance from two vertebrate hosts. Vaccination with this attenuated mutant
induced a strong host response and offered complete against blood stream infection and tick transmission
challenges with wild-type E. cahffeensis. Our further studies suggest that the ECH_0660 homologs are well
conserved among different Ehrlichia/Anaplasma species. Together, our extensive research forms the strong
foundation and premise for the proposed project. In this proposal, we will test the hypothesis that attenuation
through a functional deficiency in the E. chaffeensis ECH_0660 gene and its homologs in other related
rickettsials will result in safe and efficacious vaccines that are sufficient to prevent wild type infection into the
blood stream or from tick transmission; the two possible means by which tick-borne rickettsials cause
infections in people. We propose the following three specific aims: 1) Evaluate the duration of immunity
offered by the ECH_0660 gene mutant live attenuated vaccine (MLAV) against wild type infection challenge
through blood stream and tick-transmission. 2) Evaluate the protection of the MLAV against genetically distinct
E. chaffeensis strains. 3) Evaluate ECH_0660 gene homolog mutants in related Ehrlichia and Anaplasma
species for their efficacy as live attenuated vaccines in conferring protection against the pathogens' infection
into blood stream and by tick-transmission. The goals represent a logical extension of the substantial progress
we have made from our ongoing research. Further, we have included a rigorous experimental plan to execute
the project goals, which are critical in advancing the development of vaccines to prevent diseases caused by
several important tick-transmitted Ehrlichia and Anaplasma species pathogens. We have the high-level
expertise and ...

## Key facts

- **NIH application ID:** 10399534
- **Project number:** 5R01AI152418-03
- **Recipient organization:** KANSAS STATE UNIVERSITY
- **Principal Investigator:** ROMAN R. GANTA
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $622,465
- **Award type:** 5
- **Project period:** 2020-06-01 → 2022-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10399534

## Citation

> US National Institutes of Health, RePORTER application 10399534, Vaccines Against Ehrlichia and Anaplasma Species Infections (5R01AI152418-03). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10399534. Licensed CC0.

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