Quantitative differences in salivary pathogen load during tick transmission underlie strain-specific variation in transmission efficiency of Anaplasma marginale

Massaro W Ueti; Donald P Knowles; Christine M Davitt; Glen A Scoles; Timothy V Baszler; Guy H Palmer

doi:10.1128/IAI.01164-08

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Quantitative differences in salivary pathogen load during tick transmission underlie strain-specific variation in transmission efficiency of Anaplasma marginale

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Quantitative differences in salivary pathogen load during tick transmission underlie strain-specific variation in transmission efficiency of Anaplasma marginale

Massaro W Ueti, Donald P Knowles, Christine M Davitt, Glen A Scoles, Timothy V Baszler and Guy H Palmer

Infection and immunity, Vol.77(1), pp.70-75

01/2009

DOI: https://doi.org/10.1128/IAI.01164-08

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https://hdl.handle.net/2376/108899

PMCID: PMC2612265

PMID: 18955472

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Abstract

Anaplasma marginale - growth & development

Host-Pathogen Interactions

Animals

Tick-Borne Diseases - transmission

Cattle

Saliva - microbiology

Salivary Glands - microbiology

Colony Count, Microbial

Anaplasma marginale - isolation & purification

Ticks - microbiology

The relative fitness of arthropod-borne pathogens within the vector can be a major determinant of pathogen prevalence within the mammalian host population. Strains of the tick-borne rickettsia Anaplasma marginale differ markedly in transmission efficiency, with a consequent impact on pathogen strain structure. We have identified two A. marginale strains with significant differences in the transmission phenotype that is effected following infection of the salivary gland. We have proposed competing hypotheses to explain the phenotypes: (i) both strains are secreted equally, but there is an intrinsic difference in infectivity for the mammalian host, or (ii) one strain is secreted at a significantly higher level and thus represents delivery of a greater pathogen dose. Quantitative analysis of pathogen replication and secretion revealed that the high-efficiency St. Maries strain replicated to a 10-fold-higher titer and that a significantly greater percentage of infected ticks secreted A. marginale into the saliva and did so at a significantly higher level than for the low-efficiency Israel vaccine strain. Furthermore, the transmission phenotype of the vaccine strain could be restored to that of the St. Maries strain simply by increasing the delivered pathogen dose, either by direct inoculation of salivary gland organisms or by increasing the number of ticks during transmission feeding. We identified morphological differences in the colonization of each strain within the salivary glands and propose that these reflect strain-specific differences in replication and secretion pathways linked to the vector-pathogen interaction.

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Title: Quantitative differences in salivary pathogen load during tick transmission underlie strain-specific variation in transmission efficiency of Anaplasma marginale
Creators: Massaro W Ueti - Department of Veterinary Microbiology and Pathology, Washington State University, Pullman, WA 99164-7040, USA. massaro@vetmed.wsu.edu
Donald P Knowles
Christine M Davitt
Glen A Scoles
Timothy V Baszler
Guy H Palmer
Publication Details: Infection and immunity, Vol.77(1), pp.70-75
Academic Unit: Veterinary Microbiology and Pathology, Department of; Paul G. Allen School for Global Animal Health
Publisher: United States
Grant note: T32 AI007025 / NIAID NIH HHS R37 AI044005 / NIAID NIH HHS GR075800M / Wellcome Trust R01 AI044005 / NIAID NIH HHS AI44005 / NIAID NIH HHS
Identifiers: 99900547125601842
Language: English
Resource Type: Journal article