Differential expression analysis for subolesin in Rhipicephalus microplus infected with Anaplasma marginale

Molecular and Serological Identification of Anaplasma marginale and Borrelia burgdorferi in Cattle and Ticks from Nuevo Leon, Northern Mexico

Ticks and tick-borne diseases affect livestock productivity and cause significant economic losses. Therefore, surveillance of these pathogens and vectors is paramount to reducing these effects in livestock. This study aimed to identify Anaplasma marginale and Borrelia burgdorferi sensu lato in ticks collected from cattle. Molecular biology techniques were utilized to identify A. marginale for both types of samples, i.e., ticks and bovine blood. Serology of cattle using indirect immunofluorescence assay (IFA) was conducted to determine antibodies to B. burgdorferi s.l. from seven locations in Nuevo Leon, Mexico, between 2015 and 2017. From 404 bovines, 2880 ticks were collected: Rhipicephalus microplus (2391 females and 395 males), Amblyomma spp. (51 females and 42 males) and Dermacentor variabilis (1 female). Rhipicephalus microplus represented the largest specimens captured, with 96.7% within the seven study sites. PCR processed only 15% (442) of tick samples to identify A. marginale. Field genera proportions were followed to select testing tick numbers. Results showed that 9.9% (44/442) of A. maginale infected the pooled tick species, whereas the highest percent corresponded to 9.4% (38/404) in R. microplus. Regarding the molecular analysis of blood samples, 214 of 337 (63.5%) were positive for A. maginale. In each of the seven locations, at least one bovine sample tested positive for A. maginale. Borrelia burgdorferi s.l. was not found either in the ticks or serum samples. Two A.marginale DNA nucleotide sequences obtained in this study were deposited in the GenBank with the following accession numbers OR050501 cattle, and OR050500 R.microplus tick. Results of this work point to current distribution of bovine anaplasmosis in northern Mexico.

Coxiella Endosymbiont of Rhipicephalus microplus Modulates Tick Physiology With a Major Impact in Blood Feeding Capacity

In the past decade, metagenomics studies exploring tick microbiota have revealed widespread interactions between bacteria and arthropods, including symbiotic interactions. Functional studies showed that obligate endosymbionts contribute to tick biology, affecting reproductive fitness and molting. Understanding the molecular basis of the interaction between ticks and their mutualist endosymbionts may help to develop control methods based on microbiome manipulation. Previously, we showed that Rhipicephalus microplus larvae with reduced levels of Coxiella endosymbiont of R. microplus (CERM) were arrested at the metanymph life stage (partially engorged nymph) and did not molt into adults. In this study, we performed a transcriptomic differential analysis of the R. microplus metanymph in the presence and absence of its mutualist endosymbiont. The lack of CERM resulted in an altered expression profile of transcripts from several functional categories. Gene products such as DA-P36, protease inhibitors, metalloproteases, and evasins, which are involved in blood feeding capacity, were underexpressed in CERM-free metanymphs. Disregulation in genes related to extracellular matrix remodeling was also observed in the absence of the symbiont. Taken together, the observed alterations in gene expression may explain the blockage of development at the metanymph stage and reveal a novel physiological aspect of the symbiont-tick-vertebrate host interaction.

Molecular Cloning and Expression Analysis of Enolase in the Rhipicephalus microplus (Acari: Ixodidae)

Rhipicephalus microplus is the main blooding-sucking ectoparasite of bovines and is regarded as important vectors of animal diseases such as Babesiosis. Mining protective antigens of R. microplus to develop antitick vaccine is the most potential tick control strategy. In this study, the specific primers were designed according to the conserved nucleotide sequence of enolase gene in Haemaphysalis flava, Ixodes ricinus, and Ornithodoros moubata. The fragment of enolase gene was obtained by PCR using cDNA template from fully engorged female R. microplus. The full-length cDNA of enolase gene was amplified using rapid amplification of cDNA ends (RACE). Expression pattern of enolase gene in different tissues of R. microplus was analyzed by real-time quantitative PCR (qRT-PCR). Results showed that the full-length enolase cDNA containing 2052 bp was obtained successfully. The complete cDNA included an ORF of 1305 nucleotides encoding a protein of 434 amino acids. The enolase exhibited 85.0% amino acid identity to the enolase of H. flava, 81.1% to I. ricinus enolase, and 81.3% to O. moubata enolase. qRT-PCR analysis indicated that the enolase had the highest expression in the salivary gland of R. microplus.