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Association of pathogen strain-specific gene transcription and transmission efficiency phenotype of Anaplasma

Joseph T Agnes1, David Herndon, Massaro W Ueti

  • 1Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040, USA. jagnes@vetmed.wsu.edu

Infection and Immunity
|March 24, 2010
PubMed

Insights

Differences in Anaplasma marginale strains

Area of Science:

  • Microbiology
  • Vector-borne diseases
  • Genomics

Background:

  • Efficient pathogen transmission by arthropod vectors depends on pathogen replication and infectiousness within the vector.
  • Determinants of transmission efficiency for many bacterial and protozoan pathogens remain largely unknown.
  • Anaplasma marginale strains exhibit varying transmission efficiencies, with implications for disease spread.

Purpose of the Study:

  • To investigate the role of strain-specific genes in Anaplasma marginale transmission efficiency.
  • To identify genes expressed in the tick salivary gland that correlate with transmission efficiency differences between strains.
  • To explore the functional significance of these strain-specific genes in the context of vector colonization and pathogen infectivity.

Main Methods:

  • Comparative genomics using annotation-dependent and -independent analyses to identify strain-specific genes.
  • Whole-genome sequencing of high and low transmission efficiency Anaplasma marginale strains.
  • Transcriptional analysis of identified strain-specific genes in tick salivary glands at the time of pathogen transmission.

Main Results:

  • Identified 58 strain-specific genes between the high-transmission St. Maries strain and the low-transmission Israel vaccine strain of Anaplasma marginale.
  • Found that 20 St. Maries strain-specific genes and 16 Israel strain-specific genes were transcribed in the tick salivary gland during transmission.
  • Observed that expression levels of these strain-specific genes in the salivary gland were comparable to or lower than those in infected erythrocytes, suggesting broader functions.

Conclusions:

  • Strain-specific genes expressed in the tick salivary gland are associated with Anaplasma marginale transmission efficiency.
  • The identified genes likely arose from divergence from common ancestral genes rather than recent lateral gene transfer.
  • The function of these strain-specific genes may extend beyond salivary gland colonization, impacting pathogen infectivity in the mammalian host.

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