Transovarial Transmission of Anaplasma marginale in Rhipicephalus (Boophilus) microplus Ticks Results in a Bottleneck for Strain Diversity

DE LA FOURNIÈRE, SOFÍA; GUILLEMI, ELIANA CAROLINA; PAOLETTA, MARTINA SOLEDAD; PÉREZ, AGUSTINA; OBREGÓN, DASIEL; CABEZAS-CRUZ, ALEJANDRO; SARMIENTO, NÉSTOR FABIÁN; FARBER, MARISA DIANA

Pathogens

MDPI

Año: 2023 vol. 12

Anaplasma marginale is an obligate intraerythrocytic bacterium of bovines, responsible forlarge economic losses worldwide. It is mainly transmitted by Rhipicephalus (Boophilus) microplusticks and, despite mounting evidence suggesting transovarial transmission, the occurrence of thisphenomenon remains controversial. We evaluated the vector competence of R. microplus larvaevertically infected with A. marginale to transmit the bacterium to a naïve bovine. A subgroup ofengorged female ticks collected from an A. marginale-positive animal was dissected and the presenceof the pathogen in its tissues was confirmed. A second subgroup of ticks was placed under controlledconditions for oviposition. After confirming the presence of A. marginale in the hatched larvae,an experimental infestation assay was conducted. Larvae were placed on an A. marginale-freesplenectomized calf. The bacterium was detected in the experimentally infested bovine 22 dayspost-infestation. We analyzed the A. marginale diversity throughout the transmission cycle using themolecular marker MSP1a. Different genotypes were detected in the mammalian and arthropod hostsshowing a reduction of strain diversity along the transmission process. Our results demonstrate thevertical transmission of A. marginale from R. microplus females to its larvae, their vector competenceto transmit the pathogen, and a bottleneck in A. marginale strain diversity.