Comparison of Seroprevalence and Identification of Risk Factors for Theileria equi in Horses From Vector-Free and Infested Areas in Southern Brazil.

The apicomplexan hemoprotozoan Theileria equi is a tick-borne pathogen that causes disease in equids, and together with Babesia caballi, causes equine piroplasmosis (EP). Many ticks are associated with EP around the world, and in South America three species may be related: Dermacentor nitens, Amblyomma sculptum, and Rhipicephalus microplus, as they are commonly found in horses. Among the species cited above, only R. microplus is found in Rio Grande do Sul state, Southern Brazil. In addition, this state has the only area legally free of R. microplus in Brazil. This study aimed to compare the seroprevalence for T. equi on farms located in a tick-free area (23 farms, 215 horses) and a tick-infested (25 farms, 141 horses) adjacent areas, as well as to identify potential risk factors for exposure to T. equi. Blood was collected from 356 horses from both areas, and later an indirect enzyme-linked immunosorbent assay was performed to detect anti-T. equi antibodies. Besides the blood collection, questionnaires and interviews were conducted in an attempt to identify potential risk factors. The R. microplus-free zone had 6% seropositive horses against 70% in the tick-infested zone. Previous observation of ticks on horses of the herd increased four times the odds of a horse to be seropositive for T. equi, and by three times if ticks were observed on cattle which share paddocks with horses on the farm. The results showed a large difference in T. equi seroprevalence between tick-infested and free areas, and also emphasized the relevance of R. microplus in the epidemiology of T. equi. The study also reveals the potential of the establishment of a T. equi-free zone for horse breeding in Southern Brazil.

Genomic analysis on Brazilian strains of Anaplasma marginale / Análise genômica de cepas Brasileiras de Anaplasma marginale

Abstract Anaplasma marginale is a vector-borne pathogen that causes a disease known as anaplasmosis. No sequenced genomes of Brazilian strains are yet available. The aim of this work was to compare whole genomes of Brazilian strains of A. marginale (Palmeira and Jaboticabal) with genomes of strains from other regions (USA and Australia strains). Genome sequencing of Brazilian strains was performed by means of next-generation sequencing. Reads were mapped using the genome of the Florida strain of A. marginale as a reference sequence. Single nucleotide polymorphisms (SNPs) and insertions/deletions (INDELs) were identified. The data showed that two Brazilian strains grouped together in one particular clade, which grouped in a larger American group together with North American strains. Moreover, some important differences in surface proteins between the two Brazilian isolates can be discerned. These results shed light on the evolutionary history of A. marginale and provide the first genome information on South American isolates. Assessing the genome sequences of strains from different regions is essential for increasing knowledge of the pan-genome of this bacteria.

Resumo Anaplasma marginale é um patógeno transmitido por vetores que causam uma doença conhecida como anaplasmose. Até a presente data, não há genomas sequenciados de cepas brasileiras. O objetivo deste estudo foi comparar o genoma completo das cepas brasileiras de A. marginale (Palmeira e Jaboticabal) com os genomas de cepas de outras regiões (cepas dos EUA e Austrália). As sequências dos genomas das cepas brasileiras foram obtidas mediante sequenciamento de nova geração. As "reads" foram mapeadas usando-se como referência o genoma de A. marginale da cepa Florida. Foram identificados polimorfismos de nucleotídeo único (SNPs) e analisadas inserções/deleções (INDELs). As duas linhagens brasileiras se agruparam em um clado particular que, por sua vez, agrupou-se em um grupo maior junto com as linhagens norte-americanas. Além disso, foram identificadas diferenças significativas nas proteínas de superfície entre os dois isolados brasileiros. Esses resultados lançam luz sobre a história evolutiva de A. marginale e fornecem as primeiras informações de genomas de isolados sul-americanos. Avaliar as sequências de genomas de cepas de diferentes regiões é essencial para aumentar o conhecimento do pan-genoma dessa bactéria.