Molecular and recombinant characterization of major surface protein 5 from Anaplasma marginale

Recombinant expression and characterization of Canine circovirus capsid protein for diagnosis

Canine circovirus (CanineCV) is a contagious virus that causes severe gastroenteritis, diarrhea, respiratory disease, and vasculitis, often resulting in fatality among infected dogs. In this study, a recombinant Capsid protein (rCap) of CanineCV was expressed in the Escherichia coli (E. coli) Rosetta (DE3) pLysS host cell, followed by affinity purification, and then analyzed by SDS-PAGE, revealing a molecular weight of approximately 31 kDa. The antigenicity of the CanineCV rCap protein was confirmed through recognition by a rabbit anti-CanineCV rCap protein polyclonal antibody (PoAb). Additionally, the reactivity and specificity of this PoAb were assessed using indirect enzyme-linked immunosorbent assay (ELISA) and Western blot analysis before applying in an immunohistochemistry (IHC), namely, immunoperoxidase detection. The immunoperoxidase assay using rabbit anti-CanineCV rCap protein PoAb demonstrated that the CanineCV Cap protein was predominantly located in immune cells, especially lymphocytes and macrophages, within the spleen, lung, tracheobronchial lymph nodes, small intestine, and kidney. Similarly, the Cap protein was also found in pneumocytes in the lung and renal tubular epithelial cells in the kidney. These findings reflected the biological activity and cell tropism of the virus. Therefore, the recombinant Cap protein and its PoAb could be used for the development of a valuable diagnostic tool for CanineCV detection.

RPA-CRISPR/Cas12a assay for the diagnosis of bovine Anaplasma marginale infection

Anaplasma marginale infection is one of the most common tick-borne diseases, causing a substantial loss in the beef and dairy production industries. Once infected, the pathogen remains in the cattle for life, allowing the parasites to spread to healthy animals. Since clinical manifestations of anaplasmosis occur late in the disease, a sensitive, accurate, and affordable pathogen identification is crucial in preventing and controlling the infection. To this end, we developed an RPA-CRISPR/Cas12a assay specific to A. marginale infection in bovines targeting the msp4 gene. Our assay is performed at one moderately high temperature, producing fluorescent signals or positive readout of a lateral flow dipstick, which is as sensitive as conventional PCR-based DNA amplification. This RPA-CRISPR/Cas12a assay can detect as few as 4 copies/μl of Anaplasma using msp4 marker without cross-reactivity to other common bovine pathogens. Lyophilized components of the assay can be stored at room temperature for an extended period, indicating its potential for field diagnosis and low-resource settings of anaplasmosis in bovines.

Molecular occurrence and genetic diversity of Ehrlichia canis in naturally infected dogs from Thailand

Canine monocytic ehrlichiosis is cause by Ehrlichia canis resulting in hematologic disorders and severe clinical signs. The aim of this study was to scrutinize the molecular detection and genetic diversity of E. canis based on the trp36 gene in dogs from Thailand's northern and central regions. A total of 120 dogs blood samples were amplified for trp36 gene of E. canis using the polymerase chain reaction (PCR). Forty-seven out of 120 dog blood samples (39.16%, 47/120) were positive for E. canis the trp36 DNA with 790 bp of PCR amplicon size. The factor significantly associated with E. canis infection is animal housing status (p < 0.05). Sequence and phylogenetic analysis showed that E. canis trp36 gene of Thailand isolates was clustered into 1st clade with similarity ranging from 95.65 to 100% together with the US genogroup. The 14 haplotypes of the trp36 gene shown in TCS network exhibited that haplotype #1-4 was found in Thailand. The entropy analysis of the trp36 gene illustrated 751 polymorphic sites and 271 entropy peaks of nucleic and amino acid sequences, respectively. Hence, these findings are crucial for better understanding the epidemiology of Ehrlichia infection and could be helpful for implementing control measures in Thailand.

Genetic characterization of genes encoding the major surface proteins of Anaplasma marginale from cattle isolates in Thailand reveals multiple novel variants

Bovine anaplasmosis is a serious tick-borne disease that is responsible for economic loss worldwide. The major surface proteins (MSPs), encoded by msp1 to msp5 genes of Anaplasma marginale, play an important role in host-pathogen and tick-pathogen interactions. These markers have been used for genetic characterization and phylogenetic studies. Despite domestic reports concerning suspected outbreaks of anaplasmosis in Thailand, genetic analysis of A. marginale in the country remains largely limited. Therefore, we aim to investigate the infection rate of the rickettsia organism in the Anaplasmataceae family throughout five regions of Thailand and to further characterize the key genetic markers: msp1a, msp2, and msp5 of A. marginale. From 2016 to 2021, we collected a total of 384 cattle blood samples across 18 provinces. Overall, the infection rate of the rickettsia organism in the Anaplasmataceae family was 46.1%. Over 65% of the positive samples were confirmed as A. marginale. We successfully obtained a total of 138 A. marginale msp1a (38), msp2 (79), and msp5 (21) sequences from all regions of the country. The msp1a and msp2 genes exhibit a high degree of genetic diversity, while the msp5 gene is highly conserved among the Thai isolates. Our findings regarding msp1a corroborated the genetic heterogeneity of A. marginale strains in endemic regions worldwide. Additionally, we found multiple novel variants for the first time in the current nationwide survey. We found 45 tandem repeat characters of the msp1a sequence. Among them, 24 characters were not shared with other countries. Collectively, we expanded the extent of genetic diversity in key markers; msp1a and msp2 genes, and further confirmed the previous finding that msp5 was highly conserved. The msp1a and msp2 genes could be useful for the surveillance of newly introduced strains. The current data may also be useful in designing a vaccine containing potential epitopes of different antigens in the future.

Ehrlichia canis: Molecular characterization and genetic diversity based on the p28 and trp36 genes

Ehrlichia canis is a common tick-borne intracellular pathogen causing canine monocytic ehrlichiosis (CME) in dogs worldwide. The aims of this study were to investigate the genetic diversity and antigenicity of E. canis based on the p28 and trp36 genes in dogs in Thailand. The E. canis p28 and trp36 genes were amplified by the polymerase chain reaction (PCR) and cloned for sequencing and bioinformatic analyses. 36% (44/120) of dog blood samples were positive for E. canis DNA consisting of p28 (31%, 14/44) and trp36 (69%, 30/44) genes with 792 and 882 bp of PCR products size, respectively. The E. canis TRP36 from all Thailand sequences exhibited encoded nine amino acids (TEDSVSAPA) with 11 copies of tandem repeats along the sequences. The phylogenetic trees of E. canis, using the p28 and trp36 genes, exhibited that the Thailand isolates fell into two clades and one clade with similarity ranging from 55.95 to 100% and 100%, respectively. The results of diversity analysis revealed 10 and 20 haplotypes of the p28 and trp 36 genes, respectively. The entropy analysis of the p28 and trp36 nucleic acid sequences showed 442 and 1321 high entropy peaks respectively, whereas those of the P28 and TRP36 amino acid sequences showed 477 and 388 high entropy peaks, respectively. For B-cell epitopes analysis, the conserved amino acid of P28 and TRP36 sequences has been also demonstrated. Therefore, the results could be utilized to improve the understanding of phylogenetic relationship, genetic diversity and antigenicity of E. canis Thailand isolates.

Molecular characterization and genetic diversity of Babesia bovis and Babesia bigemina of cattle in Thailand

Babesia bovis and B. bigemina are the most common tick-borne parasites that cause bovine babesiosis which effects livestock production, leading to economic losses in tropical and subtropical areas of the world. The aims of this study were to determine the molecular detection, genetic diversity and antigenicity prediction of B. bovis based on spherical body protein 2 (sbp-2) gene and B. bigemina based on rhoptry-associated protein 1a (rap-1a) gene in cattle in Thailand. By PCR assay, the molecular detection of B. bovis and B. bigemina infection revealed levels of 2.58% (4/155) and 5.80% (9/155), respectively. The phylograms showed that B. bovis sbp-2 and B. bigemina rap-1a sequences displayed 5 and 3 clades with similarity ranging between 85.53 to 100% and 98.28 to 100%, respectively, when compared within Thailand strain. Diversity analysis of sbp-2 and rap-1a sequences showed 18 and 4 haplotypes, respectively. The entropy analysis illustrated 104 and 7 polymorphic sites of sbp-2 and rap-1a nucleic acid sequences, respectively, while those of sbp-2 and rap-1a amino acid sequences showed 46 and 4 high entropy peaks, respectively. Motifs analysis exhibited the distribution and conservation among sbp-2 and rap-1a sequences. The continuous and discontinuous B-cell epitopes have also been evaluated in this work. Therefore, our findings may be used to ameliorate the understanding inputs of molecular phylogeny, genetic diversity and antigenicity of B. bovis and B. bigemina Thailand stains.

Bovine Anaplasmosis: Will there ever be an almighty effective vaccine?

Bovine anaplasmosis is a tick-borne bacterial disease with a worldwide distribution and the cause of severe economic losses in the livestock industry in many countries, including México. In the present work, we first review the elements of the immune response of the bovine, which allows ameliorating the clinical signs while eliminating the majority of the blood forms and generating an immunologic memory such that future confrontations with the pathogen will not end in disease. On the other hand, many vaccine candidates have been evaluated for the control of bovine anaplasmosis yet without no commercial worldwide effective vaccine. Lastly, the diversity of the pathogen and how this diversity has impaired the many efforts to control the disease are reviewed.

First study on molecular detection of three major canine tick-borne pathogens in subclinically infected dogs in Chiang Mai, Thailand

Background and Aim:

Canine tick-borne pathogens (CTBPs) are an important cause of morbidity in dogs in Thailand. This study aimed to evaluate the occurrence of three CTBPs in clinically normal, owned dogs to understand the risk for the general canine population. We also examined sex, age, tick infestation, and packed cell volume (PCV) of the animals in association with active infection of the CTBPs.

Materials and Methods:

A total of 139 dogs were included in the study. Blood samples were collected for thin blood smear, PCV and nested polymerase chain reaction (PCR) assay. Statistical analyses were performed to examine the association between individual factors and CTBP infection status determined by PCR. In addition, sensitivity, specificity, and Cohen’s kappa were calculated to assess the utility of routine blood smear.

Results:

The PCR results showed that 31 dogs (22.3%) were infected with at least one of the three pathogens. The occurrence rate for Ehrlichia canis, Anaplasma platys, and Hepatozoon canis was 2.2% (3/139), 18.7% (24/139), and 2.8% (4/139), respectively. There were two cases of coinfection with A. platys and E. canis. The univariate analyses did not yield any associations between recorded variables and the active infection. Microscopic examination showed good sensitivity and agreement only for H. canis (Sn: 75%, 95% confidence interval: 24.9-98.7, k=0.85).

Conclusion:

Our findings confirmed the endemicity of the CTBPs in owned canine population in the study site. In-depth epidemiological investigation would be warranted to elucidate environmental risk factors for CTBP infection.

Molecular genetic diversity and bioinformatic analysis of Leucocytozoon sabrazesi based on the mitochondrial genes cytb, coxI and coxIII and co-infection of Plasmodium spp

Leucocytozoon sabrazesi is an intracellular haemoprotozoan parasite responsible for leucocytozoonosis, which is transmitted by insect vectors and affects chickens in tropical and subtropical areas in many countries. It causes huge economic losses due to decreased meat and egg production. In the present study, we used nested PCR to determine the genetic diversity of L. sabrazesi based on the cytb, coxI, coxIII and concatenated genes in chickens in Thailand. In addition, we found co-infections between L. sabrazesi and Plasmodium spp. (P. gallinaceum or P. juxtanucleare) in chickens that were not identified by microscopic examination of blood smears. The phylogenetic analysis indicated that L. sabrazesi cytb and coxIII genes were conserved with similarity ranging from 99.9 to 100% and 98 to 100%, respectively whereas the coxI gene was diverse, with similarities ranging from 97 to 100%. These findings ascertained the nucleotide analysis of the cytb, coxI, coxIII and concatenated sequences in which 4, 8, 10 and 9 haplotypes were found, respectively. In addition, it was found that the large number of synonymous substitutions and conservative amino acid replacements in these mitochondrial genes occurred by non-synonymous substitution. The evolutionary analysis of the K_a/K_s ratio supported purifying selection and the negative values of both Fu’s Fs and Tajima’s D indicate selective sweep especially for the coxI gene. The entropy and Simplot analysis showed that the genetic variation in populations of Plasmodium spp. was higher than in Leucocytozoon. Hence, the nucleotide sequences of three mitochondrial genes could reflect the evolutionary analysis and geographic distribution of this protozoan population that switches hosts during its life cycle.

Molecular characterization of Anaplasma marginale based on the msp1a and msp1b genes

Anaplasma marginale is an intracellular rickettsial bacterium causing anaplasmosis in ruminants. A. marginale is transmitted biologically by ticks and mechanically by blood-sucking vectors. Anaplasmosis occurs in tropical and subtropical areas of the world. This disease causes huge economic losses due to decreasing meat yield and milk production. The aims of this study were to determine the genetic diversity and antigenicity of A. marginale based on the msp1a and msp1b genes in cattle in Thailand. The A. marginale msp1a and msp1b genes were amplified by the polymerase chain reaction (PCR). There have been four copies of MSP1a tandem repeats among A. marginale Thailand strain, and thirteen different MSP1a tandem repeats were found including repeats B, 25, 27, M, 3, S, C, H, β, 80, 4, TH1 and TH2. Notably, this study showed two copies of the novel conserved tandem sequences namely Thailand Type 1 (TH1) and Type 2 (TH2). The phylogenetic analysis revealed that A. marginale msp1a and msp1b genes were genetically diverse and showed 9 and 5 clades with similarity ranging from 98 to 100% and 79.5 to 100%, respectively, when compared within the isolates of this study. The results of diversity analysis showed 18 and 16 haplotypes of the msp1a and msp1b genes, respectively. The entropy analyses of msp1a and msp1b nucleic acid sequences showed 39 and 900 high entropy peaks with values ranging from 0.35 to 0.85 and from 0.41 to 1.48, respectively, while those of MSP1a and MSP1b amino acid sequences exhibited 75 and 72 high entropy peaks with values ranging from 0.35 to 1.06 and from 0.41 to 1.55, respectively. In addition, B-cell and T-cell epitopes have also been investigated in this study. Hence, our results could be employed to improve the insight input of molecular phylogenetics, genetic diversity and antigenicity of A. marginale Thailand strain.