Theileria orientalis is a benign bovine protozoan parasite that occasionally causes serious economic loss in the livestock industry. We report the findings of a molecular epidemiological survey of T. orientalis in 94 Vietnamese yellow cattle, 43 water buffaloes, 21 sheep, 21 goats and 85 blood-sucking ticks of cattle in the Thua Thien Hue province of Vietnam. The major piroplasm surface protein (MPSP) gene of T. orientalis was detected using polymerase chain reaction from 13 cattle (13.8%), 11 water buffaloes (25.6%), 1 sheep (4.8%) and 9 ticks (10.6%). Phylogenetic analysis using MPSP gene sequences showed the presence of seven genotypes, four previously categorized genotypes (Types 1, 3, 5 and 7) and three new genotypes (Types N-1, N-2 and N-3).

Hemoprotozoan infections often cause serious production losses in livestock. In the present study, we conducted a PCR-based survey of Babesia bovis, Babesia bigemina, Theileria annulata, Theileria orientalis, Trypanosoma evansi and Trypanosoma theileri, using 423 DNA samples extracted from blood samples of cattle (n=202), water buffaloes (n=43), sheep (n=51) and goats (n=127) bred in the Hue and Hanoi provinces of Vietnam. With the exception of T. annulata and T. evansi, all other parasite species (B. bovis, B. bigemina, T. orientalis and T. theileri) were detected in the cattle populations with B. bovis being the most common among them. Additionally, four water buffaloes and a single goat were infected with B. bovis and B. bigemina, respectively. The Hue province had more hemoprotozoan-positive animals than those from the Hanoi region. In the phylogenetic analyses, B. bovis-MSA-2b, B. bigemina-AMA-1 and T. theileri-CATL gene sequences were dispersed across four, one and three different clades in the respective phylograms. This is the first study in which the presence of Babesia, Theileria and Trypanosoma parasites was simultaneously investigated by PCR in Vietnam. The findings suggest that hemoprotozoan parasites, some of which are genetically diverse, continue to be a threat to the livestock industry in this country.

The production and roles of endogenous tumor necrosis factor alpha (TNF‐α) and gamma interferon (IFN‐γ) in the infection of Corynebacterium (C.) pseudotuberculosis were investigated in mice. The maximum levels of TNF‐α and IFN‐γ were detected on day 4 after infection. The administration of anti‐TNF‐α monoclonal antibody (mAb) as well as anti‐IFN‐γ mAb increased bacterial proliferation in the organs, leading to the death of infected mice, but anti‐IFN‐γ mAb showed a less marked effect than anti‐TNF‐α mAb. The suppressive effect of anti‐TNF‐α and anti‐IFN‐γ mAbs on anticorynebacterial resistance was augmented by the simultaneous administration of these antibodies. Anti‐TNF‐α mAb was found to be highly effective when administered on day 0 and day 4, suggesting that TNF‐α produced during the early stage of infection is critical for the generation of resistance. Histologically, many microabscesses, severe follicular swelling and lymphocyte destruction were observed in mice treated with anti‐TNF‐α or anti‐IFN‐γ mAb. Injection of anti‐CD4 or anti‐CD8 mAb also resulted in significantly increased mortality and a marked suppression of IFN‐γ production, but had no effect on TNF‐α production. Carrageenan also showed a marked effect on the exacerbation of infection. Taken together, these results suggest that endogenously produced TNF‐α and IFN‐γ are both essential to the host defense against C. pseudotuberculosis infection and that these cytokines may have an additive effect.

ABSTRACT. Babesia ovata is a tick-transmitted hemoprotozoan parasite that infects cattle. In our study, bovine blood samples (n=2,034) were collected from 10 different countries (Brazil, China, Ghana, Japan, Mongolia, the Philippines, South Africa, Sri Lanka, Thailand and Vietnam) and DNA extracted. The DNA samples were screened using an established and specific polymerase chain reaction (PCR) assay targeting the Apical membrane antigen 1 (AMA-1) gene. Parasite DNA was detected among samples collected from Japan, Mongolia and Thailand. Sequence analyses confirmed that the PCR assay detected only B. ovata AMA-1, and that amplicons from different geographical locations were conserved. Our findings highlight the importance of designing adequate strategies to control B. ovata infection in Japan, Mongolia, and Thailand.

A PCR-based survey of hemoprotozoa parasites detected Babesia bigemina, Theileria orientalis and Trypanosoma theileri among cattle and water buffalo in Vietnam, and a new Babesia sp. closely related to Babesia ovata was detected in cattle only. In addition, Theileria annulata and Trypanosoma evansi were not detected in both cattle and water buffalo. Phylogenetic analysis detected T. orientalis MPSP genotypes 3, 5, 7 and N3 in cattle and 5, 7, N1 and N2 in water buffalo. Additionally, water buffalo-derived T. theileri CATL sequences clustered together with a previously reported cattle-derived sequence from Vietnam. This is the first report of a new Babesia sp. in cattle, and T. orientalis MPSP genotype 7 and T. theileri in water buffalo in Vietnam.