• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer
  • Locations:
  • Canyon
  • Center
  • College Station
  • Gonzales
  • TVMDL Career Center
  • Contact Us

Texas A&M Veterinary Medical Diagnostic Laboratory

Apple App

download on the Apple App Store
download the app on Google Play

Search

Translate:

  • Find a Form
  • Deliver a Sample
    • Specimen Collection Information
    • Packaging Samples for Shipment
    • Drop Off a Sample
    • Cremation
    • Order Supplies
  • Client Portal
    • Get Test Results
    • SVA Portal
    • Pay a Bill
  • Become a Client
  • Resources
    • TVMDL Bovine Testing Guidance and Reference Material
    • Diagnostic Plans
      • Bovine Syndromic Diagnostic Plans
      • Equine Syndromic Diagnostic Plans
      • Small Ruminant Syndromic Diagnostic Plans
      • Small Animal Syndromic Diagnostic Plans
    • Education Library
    • Case Study Library
    • Electronic Reporting: QR Coding Process
    • CoreOne Resources
  • About Us
    • Locations and Hours
    • Agency Leadership
    • Speaker’s Bureau
    • Texas Pullorum-Typhoid Program
    • TVMDL Mobile app
    • Contact Us
  • Locations
    • College Station Laboratory
    • Canyon Laboratory
    • Center Laboratory
    • Gonzales Laboratory
  • Contact Us

Collaborative project leads to improved diagnostic detection of strangles

September 21, 2022 by Mallory Pfeifer

Research initiated at the Equine Infectious Disease Laboratory (EIDL) at Texas A&M University aimed at exploring the genomic components of strangles has now led to an improved assay at the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL).

Strangles is caused by the bacterium Streptococcus equi subspecies equi (S. equi) and is a highly contagious disease that affects the upper respiratory system and lymph nodes of horses.  Though it maybe suspected due to clinical signs, diagnostic detection is the only definitive method of identifying strangles. The ancestor of S. equi, Streptococcus equi subsp. zooepidemicus (S. zoo), is considered a commensal organism and may cause pneumonia, endometriosis, and abortion in horses. Together, both organisms contribute to high morbidity and variable mortality among horses.

As a graduate research assistant at the EIDL, Ellen Ruth Alexander Morris, PhD, began working on the project in early 2020 with Dr. Noah Cohen, Director of the EIDL.

“There was no initial plan to develop a new assay,” Alexander Morris said. “The idea evolved from another ongoing project, where we were examining the genome-wide differences between 50 strains of S. equi and 50 strains of S. zoo using whole genome sequencing.”

Their evaluation of the different strains led to the development of additional primers, which are DNA sequences that can be used to detect both S. equi and S. zoo.

Current detection methods
Classically, strangles was detected by culturing S. equi and S. zoo; a slow and less sensitive method. Over time, multiple tests using polymerase chain reaction (PCR) technology have been developed to detect S. equiand S. zoo individually.

Although quicker and more sensitive than bacterial culture, PCR testing for strangles is still somewhat limited. PCR testing uses primers to target specific DNA sequences to determine an organism’s presence. Because of the genetic similarities between S. equi and S. zoo, some tests may not be able to differentiate between the two organisms and lead to false positives. Conversely, there are instances where the typically targeted sequence of S. equi has been truncated or deleted and therefore testing leads to a false negative. Other PCR tests, such as the one previously offered at TVMDL, cannot differentiate coinfection with S. equiand S. zoo due to the organisms’ multiple genetic similarities.

Improved PCR testing
The new primers were designed from S. equi and S. zoo strains collected from clinical samples of Texas horses and using publicly available S. equi and S. zoo strains from across the world. TVMDL’s molecular diagnostics section performed validation testing using the new primers and determined they could be used to detect and differentiate between S. equi and S. zoo. This assay also includes an internal control that serves as a monitor for PCR efficiency and sample inhibition. Following validation, TVMDL can now use these primers for routine diagnostic testing.

“Our hope is these new PCR targets will aid in the diagnosis of strangles, identify cases of concurrent infection of S. equi and S. zoo, or improve differentiation between the two organisms,” Alexander Morris, who is now a postdoctoral research assistant at TVMDL, said.

TVMDL now offers an improved version of Streptococcus equi Multiplex (rtPCR) at the College Station and Canyon laboratories. For more information on this test, or other equine testing options, visit tvmdl.tamu.edu or call the College Station or Canyon laboratories. To learn more about EIDL, visit their website at vetmed.tamu.edu/eidl.

Filed Under: News, Test Catalog Updates Tagged With: bacteriology, college station, equine, horse, microbacteriology, Molecular Diagnostics, PCR, strangles, Virology

Primary Sidebar

Latest News

  • Rare case of ocular onchocerciasis in a dog from south Texas January 25, 2023
  • Dimitrov contributes to literature over avian paramyxoviruses January 24, 2023
  • *Update 1/24 Canyon lab will be closed* January 23, 2023
  • Two professionals recognized with Texas A&M AgriLife Vice Chancellor’s Awards in Excellence January 19, 2023
  • Lemburg honored with Vice Chancellor Award in Excellence January 19, 2023
  • Five employees honored with Director’s Excellence Awards January 19, 2023

Footer

For Employees

  • Employee Email
  • TVMDL Rules & Procedures
  • TVMDL Career Center
  • Emergency Alert Systems
  • AgriLife People Directory
  • AgriLife Administrative Services
  • TAMUS Single Sign On
  • Facebook

State of Texas

  • Texas.gov Portal
  • Texas Veterans Portal
  • Statewide Search
  • Texas Homeland Security
  • Risk, Fraud, & Misconduct Hotline

Policies

  • Privacy and Security Policy
  • Accessibility Policy

Sign up for our species-specific newsletters!

Sign up for our species-specific newsletters!
  • Texas A&M AgriLife
  • Texas A&M Veterinary Medical Diagnostics Laboratory
  • Texas A&M Forest Service
  • Texas A&M AgriLife Extension Service
  • Texas A&M AgriLife Research

483 Agronomy Rd
College Station, TX 77843