Proteomic analysis reveals pathogen-derived biomarkers of acute babesiosis in erythrocytes, plasma, and urine of infected hamsters

Analysis of serum proteomic profiles of endangered Siamese and Burmese Eld's deer infected with subclinical Babesia bovis in Thailand

The endangered Eld's deer is a conserved species in Thailand, where tropical parasitic infections are endemic. Although Eld's deer with babesiosis are generally asymptomatic, they can still harbor the parasite and serve as reservoirs for ticks, spreading the infection to healthy animals within the herd. The present study aimed to investigate potential serum proteome biomarkers of Eld's deer with subclinical Babesia bovis infection. A total of 67 blood samples were collected from captive Siamese and Burmese Eld's deer showing no signs of parasitic infection. The nested polymerase chain reaction (nPCR) of a conserved spherical body protein 2 (sbp-2) gene of B. bovis was utilized to classify Eld's deer groups, with 25.37 % (17/67) testing positive for B. bovis. Additionally, the application of proteomic studies showed that six B. bovis proteins, such as Obg-like ATPase 1 (OLA1) and heat shock protein 90 (HSP90), were significantly upregulated by more than a two-fold change compared with the PCR-negative samples. Of the 55 overexpressed serum proteins in the PCR-positives, alpha 2-HS glycoprotein (AHSG) and immunoglobulin lambda variable 2-8 (IGLV2-8) were notably among the top 10 proteins with the highest area under curve (AUC) values. Hence, they were proposed as potential biomarkers for subclinical B. bovis infection in Eld's deer. Analysis of the protein interaction network revealed interactions between Eld's deer AHSG and B. bovis OLA1 and HSP90, alongside associations with other proteins such as erb-b2 receptor tyrosine kinase 2 (ERBB2) and epidermal growth factor receptor (EGFR). These interactions were involved in the immune system pathway and inflammatory responses. Our findings shed light on subclinical infection of B. bovis in Eld's deer and identify potential biomarkers, contributing to the further effective detection and monitoring of B. bovis infection in this endangered species.

Specific and Sensitive Diagnosis of Babesia microti Active Infection Using Monoclonal Antibodies to the Immunodominant Antigen BmGPI12

The apicomplexan pathogen Babesia microti is responsible for most cases of human babesiosis worldwide. The disease, which presents as a malaria-like illness, is potentially fatal in immunocompromised or elderly patients, making the need for its accurate and early diagnosis an urgent public health concern. B. microti is transmitted primarily by Ixodes ticks but can also be transmitted via blood transfusion. The parasite completes its asexual reproduction in the host red blood cell, where each invading merozoite develops and multiplies to produce four daughter parasites. While various techniques, such as microscopy, PCR, and indirect fluorescence, have been used over the years for babesiosis diagnosis, detection of the secreted B. microti immunodominant antigen BmGPI12 using specific polyclonal antibodies was found to be the most effective method for the diagnosis of active infection and for evaluation of clearance following drug treatment. Here, we report the development of a panel of 16 monoclonal antibodies against BmGPI12. These antibodies detected secreted BmGPI12 in the plasma of infected humans. Antigen capture assays identified a combination of two monoclonal antibodies, 4C8 and 1E11, as a basis for a monoclonal antibody-based BmGPI12 capture assay (mGPAC) to detect active B. microti infection. Using a collection of 105 previously characterized human plasma samples, the mGPAC assay showed 97.1% correlation with RNA-based PCR (transcription-mediated amplification [TMA]) for positive and negative samples. The mGPAC assay also detected BmGPI12 in the plasma of six babesiosis patients at the time of diagnosis but not in three matched posttreatment samples. The mGPAC assay could thus be used alone or in combination with other assays for accurate detection of active B. microti infection.

Babesia microti Immunoreactive Rhoptry-Associated Protein-1 Paralogs Are Ancestral Members of the Piroplasmid-Confined RAP-1 Family

Babesia, Cytauxzoon and Theileria are tick-borne apicomplexan parasites of the order Piroplasmida, responsible for diseases in humans and animals. Members of the piroplasmid rhoptry-associated protein-1 (pRAP-1) family have a signature cysteine-rich domain and are important for parasite development. We propose that the closely linked B. microti genes annotated as BMR1_03g00947 and BMR1_03g00960 encode two paralogue pRAP-1-like proteins named BmIPA48 and Bm960. The two genes are tandemly arranged head to tail, highly expressed in blood stage parasites, syntenic to rap-1 genes of other piroplasmids, and share large portions of an almost identical ~225 bp sequence located in their 5' putative regulatory regions. BmIPA48 and Bm960 proteins contain a N-terminal signal peptide, share very low sequence identity (<13%) with pRAP-1 from other species, and harbor one or more transmembrane domains. Diversification of the piroplasmid-confined prap-1 family is characterized by amplification of genes, protein domains, and a high sequence polymorphism. This suggests a functional involvement of pRAP-1 at the parasite-host interface, possibly in parasite adhesion, attachment, and/or evasion of the host immune defenses. Both BmIPA48 and Bm960 are recognized by antibodies in sera from humans infected with B. microti and might be promising candidates for developing novel serodiagnosis and vaccines.

Babesia microti: Pathogen Genomics, Genetic Variability, Immunodominant Antigens, and Pathogenesis

More than 100 Babesia spp. tick-borne parasites are known to infect mammalian and avian hosts. Babesia belong to Order Piroplasmid ranked in the Phylum Apicomplexa. Recent phylogenetic studies have revealed that of the three genera that constitute Piroplasmida, Babesia and Theileria are polyphyletic while Cytauxzoon is nested within a clade of Theileria. Several Babesia spp. and sub-types have been found to cause human disease. Babesia microti, the most common species that infects humans, is endemic in the Northeastern and upper Midwestern United States and is sporadically reported elsewhere in the world. Most infections are transmitted by Ixodid (hard-bodied) ticks, although they occasionally can be spread through blood transfusion and rarely via perinatal transmission and organ transplantation. Babesiosis most often presents as a mild to moderate disease, however infection severity ranges from asymptomatic to lethal. Diagnosis is usually confirmed by blood smear or polymerase chain reaction (PCR). Treatment consists of atovaquone and azithromycin or clindamycin and quinine and usually is effective but may be problematic in immunocompromised hosts. There is no human Babesia vaccine. B. microti genomics studies have only recently been initiated, however they already have yielded important new insights regarding the pathogen, population structure, and pathogenesis. Continued genomic research holds great promise for improving the diagnosis, management, and prevention of human babesiosis, and in particular, the identification of lineage-specific families of cell-surface proteins with potential roles in cytoadherence, immune evasion and pathogenesis.

Tick-borne zoonoses and commonly used diagnostic methods in human and veterinary medicine

Around the world, human health and animal health are closely linked in terms of the One Health concept by ticks acting as vectors for zoonotic pathogens. Animals do not only maintain tick cycles but can either be clinically affected by the same tick-borne pathogens as humans and/or play a role as reservoirs or sentinel pathogen hosts. However, the relevance of different tick-borne diseases (TBDs) may vary in human vs. veterinary medicine, which is consequently reflected by the availability of human vs. veterinary diagnostic tests. Yet, as TBDs gain importance in both fields and rare zoonotic pathogens, such as Babesia spp., are increasingly identified as causes of human disease, a One Health approach regarding development of new diagnostic tools may lead to synergistic benefits. This review gives an overview on zoonotic protozoan, bacterial and viral tick-borne pathogens worldwide, discusses commonly used diagnostic techniques for TBDs, and compares commercial availability of diagnostic tests for humans vs. domestic animals, using Germany as an example, with the aim of highlighting existing gaps and opportunities for collaboration in a One Health framework.

Evaluation of pathogen specific urinary peptides in tick-borne illnesses

Mass spectrometry enhanced by nanotechnology can achieve previously unattainable sensitivity for characterizing urinary pathogen-derived peptides. We utilized mass spectrometry enhanced by affinity hydrogel particles (analytical sensitivity = 2.5 pg/mL) to study tick pathogen-specific proteins shed in the urine of patients with (1) erythema migrans rash and acute symptoms, (2) post treatment Lyme disease syndrome (PTLDS), and (3) clinical suspicion of tick-borne illnesses (TBI). Targeted pathogens were Borrelia, Babesia, Anaplasma, Rickettsia, Ehrlichia, Bartonella, Francisella, Powassan virus, tick-borne encephalitis virus, and Colorado tick fever virus. Specificity was defined by 100% amino acid sequence identity with tick-borne pathogen proteins, evolutionary taxonomic verification for related pathogens, and no identity with human or other organisms. Using a cut off of two pathogen peptides, 9/10 acute Lyme Borreliosis patients resulted positive, while we identified zero false positive in 250 controls. Two or more pathogen peptides were identified in 40% of samples from PTLDS and TBI patients (categories 2 and 3 above, n = 59/148). Collectively, 279 distinct unique tick-borne pathogen derived peptides were identified. The number of pathogen specific peptides was directly correlated with presence or absence of symptoms reported by patients (ordinal regression pseudo-R2 = 0.392, p = 0.010). Enhanced mass spectrometry is a new tool for studying tick-borne pathogen infections.