Molecular evidence of zoonotic Babesia species, other than B. microti, in ixodid ticks collected from small mammals in the Republic of Korea

Current Status of Trypanosoma grosi and Babesia microti in Small Mammals in the Republic of Korea

Small mammals, such as rodents and shrews, are natural reservoir hosts of zoonotic diseases, including parasitic protozoa. To assess the risk of rodent-borne parasitic protozoa in the Republic of Korea (ROK), this study investigated the status of parasitic protozoa, namely Trypanosoma, Babesia, and Theileria, in small mammals. In total, 331 blood samples from small mammals were analyzed for parasites using PCR and sequenced. Samples were positive for Trypanosoma grosi (23.9%; n = 79) and Babesia microti (10%; n = 33) but not Theileria. Small mammals from Seogwipo-si showed the highest infection rate of T. grosi (48.4%), while the highest B. microti infection rate was observed in those from Gangneung-si (25.6%). Sequence data revealed T. grosi to be of the AKHA strain. Phylogenetic analysis of B. microti revealed the US and Kobe genotypes. B. microti US-type-infected small mammals were detected throughout the country, but the Kobe type was only detected in Seogwipo-si. To our knowledge, this is the first nationwide survey that confirmed T. grosi and B. microti infections at the species level in small mammals in the ROK and identified the Kobe type of B. microti. These results provide valuable information for further molecular epidemiological studies on these parasites.

Molecular detection of Babesia microti in dromedary camels in Egypt

Babesia microti (Apicomplexa: Piroplasmida) causes a medically important tick-borne zoonotic protozoan disease. Egyptian camels are susceptible to Babesia infection; however, just a few cases have been documented. This study aimed to identify Babesia species, specifically Babesia microti, and their genetic diversity in dromedary camels in Egypt and associated hard ticks. Blood and hard tick samples were taken from 133 infested dromedary camels slaughtered in Cairo and Giza abattoirs. The study was conducted from February to November 2021. The 18S rRNA gene was amplified by polymerase chain reaction (PCR) to identify Babesia species. Nested PCR targeting the β-tubulin gene was used to identify B. microti. The PCR results were confirmed by DNA sequencing. Phylogenetic analysis based on the ß-tubulin gene was used to detect and genotype B. microti. Three tick genera were identified in infested camels (Hyalomma, Rhipicephalus, and Amblyomma). Babesia species were detected in 3 out of 133 blood samples (2.3%), while Babesia spp. were not detected in hard ticks by using the 18S rRNA gene. B. microti was identified in 9 out of 133 blood samples (6.8%) and isolated from Rhipicephalus annulatus and Amblyomma cohaerens by the β-tubulin gene. The phylogenetic analysis of the β-tubulin gene revealed that USA-type B. microti was prevalent in Egyptian camels. The results of this study suggested that the Egyptian camels may be infected with Babesia spp. and the zoonotic B. microti strains, which pose a potential risk to public health.

Establishment of a Transient and Stable Transfection System for Babesia duncani Using a Homologous Recombination Strategy

Genetic modification provides an invaluable molecular tool to dissect the biology and pathogenesis of pathogens. However, no report is available about the genetic modification of Babesia duncani, a pathogen responsible for human babesiosis that is widespread in North America, suggesting the necessity to develop a genetic manipulation method to improve the strategies for studying and understanding the biology of protozoan pathogens. The establishment of a genetic modification method requires promoters, selectable markers, and reporter genes. Here, the double-copy gene elongation factor-1α (ef-1α) and its promoters were amplified by conventional PCR and confirmed by sequencing. We established a transient transfection system by using the ef-1αB promoter and the reporter gene mCherry and achieved stable transfection through homologous recombination to integrate the selection marker hDHFR-eGFP into the parasite genome. The potential of this genetic modification method was tested by knocking out the thioredoxin peroxidase-1 (TPX-1) gene, and under the drug pressure of 5 nM WR99210, 96.3% of the parasites were observed to express green fluorescence protein (eGFP) by flow cytometry at day 7 post-transfection. Additionally, the clone line of the TPX-1 knockout parasite was successfully obtained by the limiting dilution method. This study provided a transfection method for B. duncani, which may facilitate gene function research and vaccine development of B. duncani.

Molecular evidence of zoonotic Babesia species, other than B. microti, in ixodid ticks collected from small mammals in the Republic of Korea

The occurrence of tick‐borne infectious diseases, including zoonotic babesiosis, has become a serious concern in recent years. In this study, we detected Babesia spp. using polymerase chain reaction (PCR) amplification of the 18S rRNA of the parasites isolated from ixodid ticks collected from small mammals in the Republic of Korea (ROK). Sequence analysis of the PCR amplicon revealed the presence of B. duncani, B. venatorum, B. capreoli/divergens, and, the most prevalent, B. microti in the ticks. The molecular phylogenetic analysis showed that the four species‐specific18S rRNA sequences clustered in four distinct clades. This is the first study to provide molecular evidence for the presence of zoonotic Babesia spp. other than B. microti in ticks in the ROK.