Seroprevalence, Isolation, Genotyping, and Pathogenicity of Toxoplasma gondii Strains from Sheep in China.

Toxoplasma gondii is an important cause of reproductive failure in small ruminants that also poses a risk to consumers who consume undercooked meat. However, little is known about sheep toxoplasmosis in China for the world. Therefore, this study was conducted to assess the prevalence of T. gondii infection in sheep from China, to isolate T. gondii via bioassay in mice and to evaluate the virulence of the isolated T. gondii based on vero cell invasion and mice. A total of 840 samples (304 unfrozen hearts and 536 sera) from sheep in China were collected from 2014 to 2016. Heart samples (n = 36) of T. gondii seropositive sheep (MAT, ≥25) were bioassayed in mice individually. DNA derived from cell cultured tachyzoites of the isolated T. gondii was characterized by PCR-RFLP of 10 loci (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico). The virulence of the T. gondii was evaluated based on the mortality and encystation in mice, as well as their growth characteristics in cell culture. Antibodies to T. gondii were found in 174 of 840 (20.71%, 304 hearts juice and 536 sera) sheep by the modified agglutination test (cut-off 1:25). Viable T. gondii was isolated from the hearts of two of 36 seropositive sheep hearts. Both genotypes of the sheep heart isolates were ToxoDB#9. The virulence of the two ToxoDB#9 isolations varied significantly. To the best of our knowledge, this is the first report of isolation of ToxoDB#9 strain of T. gondii from sheep in China.

Isolation and genetic characterization of viable Toxoplasma gondii from tissues and feces of cats from the central region of China.

Cats are important in the epidemiology of toxoplasmosis because they are the only definitive hosts that excrete environmentally resistant Toxoplasma gondii oocysts. Little is known of feline toxoplasmosis in China and most of the literature is in Chinese. Here we summarized all published reports on feline toxoplasmosis in English and report first identification of oocyst excretion by naturally infected cats in China. Unfrozen tissues of 42 cats and feces of 360 cats from China were bioassayed in mice for isolation of T. gondii. Antibodies to T. gondii were found in 21 of 42 (50%) of cats by the modified agglutination test (cut-off 1:25). Viable T. gondii was isolated from tissues of eight of 21 seropositive but not from 21 seronegative (<1:25) cats. Viable T. gondii was isolated from feces of one cat. DNA derived from cell cultured tachyzoites of all nine T. gondii isolates was characterized by PCR-RFLP at 10 loci (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico). Four genotypes were found; the genotypes of tissue isolates were ToxoDB #9 in six, ToxoDB #2 in one, and ToxoDB #17 in one. The fecal isolate was ToxoDB #1.To our knowledge, the present study is the first isolation of T. gondii from cat feces from China.

Prevalence and Risk Factors of Intestinal Parasites in Cats from China.

The prevalence of intestinal parasites in cats from China was largely unknown prior to this study. The aim of the present study was to investigate the presence of intestinal parasites in cats from central China and also identify risk factors for parasitism. Fecal samples from 360 cats were examined using sugar flotation procedure and fecal smear test by microscope. Cats had mixed two or three kinds of parasites infections. Of the 360 cats feces, intestinal parasites positive feces were 149 (41.39%). 64 (17.78%) were infected with Toxocara cati, 61 (16.94%) with Isospora felis, 41 (11.39%) with Isospora rivolta, 33 (9.17%) with Paragonimus, 23 (6.39%) with hookworms, 11 (3.06%) with Toxoplasma-like oocysts, 10 (2.78%) with Trichuris, 4 (1.11%) with lungworm, 2 (0.56%) with Sarcocystis, and 1 (0.28%) with Trematode. The cats' living outdoor was identified as risk factor by statistical analysis. These results provide relevant basic data for assessing the infection of intestinal parasites in cats from central region of China. In conclusion, there was high prevalence of intestinal parasites in cats from China.

Marek's disease virus-encoded analog of microRNA-155 activates the oncogene c-Myc by targeting LTBP1 and suppressing the TGF-ß signaling pathway.

Marek's disease virus (MDV) is a representative alpha herpes virus able to induce rapid-onset T-cell lymphoma in its natural host and regarded as an ideal model for the study of virus-induced tumorigenesis. Recent studies have shown that the mdv1-miR-M4-5p, a viral analog of cellular miR-155, is critical for MDV׳s oncogenicity. However, the precise mechanism whereby it was involved in MD lymphomagenesis remained unknown. We have presently identified the host mRNA targets of mdv1-miR-M4-5 and identified the latent TGF-ß binding protein 1 (LTBP1) as a critical target for it. We found that during MDV infection, down-regulation of LTBP1 expression by mdv1-miR-M4-5p led to a significant decrease of the secretion and activation of TGF-ß1, with suppression of TGF-ß signaling and a significant activation of expression of c-Myc, a well-known oncogene which is critical for virus-induced tumorigenesis. Our findings reveal a novel and important mechanism of how mdv1-miR-M4-5p potentially contributes to MDV-induced tumorigenesis.

Low prevalence of Neospora caninum and Toxoplasma gondii antibodies in dogs in Jilin, Henan and Anhui Provinces of the People's Republic of China.

BACKGROUND: Neospora caninum and Toxoplasma gondii are important pathogens of worldwide distribution. N. caninum is a major cause of abortion in cattle and dogs are main reservoirs because they excrete the environmentally resistant oocysts. Toxoplasmosis is a worldwide zoonosis and dogs are considered as sentinels for this parasite because of their close contact with people and cats; additionally dog meat is also used for human consumption in China. The aim of the present study was to assess the prevalence of N. caninum and T. gondii infection in dogs from China. A total of 425 countryside dog hearts in Jilin, Henan and Anhui provinces of the People's Republic of China were collected from slaughter houses in two batches; the first batch of 96 in October 2013, and the second batch of 329 in April 2014. Serum samples extracted from 96 dog hearts were tested for antibodies to N. caninum and from 425 dog hearts were tested for T. gondii antibodies in the modified agglutination tests (cut-off 1:25 for both), using respective antigens. RESULTS: Antibodies to N. caninum were 6 of 96 (6.25%) of dogs with titers of 1:25 in 2, 1:50 in 3, and 1:100 in 1. All seropositive dogs were more than 1 year old. Antibodies to T. gondii were found in 35 of 425 (8.24%) dogs with titers of 1:25 in 15, 1:50 in 14; and 1:100 in 6. CONCLUSION: The results of the present study indicated low prevalence of N. caninum and T. gondii antibodies in dogs of China, compared with Europe and America. Identification of the risk factors that underlie these differences may help prevention of neosporosis and toxoplasmosis. This is the first report of N. caninum infection in dogs from China.

Chicken intestine defensins activated murine peripheral blood mononuclear cells through the TLR4-NF-kappaB pathway.

Defensins serve as alarm signals in mobilizing the immune system and activating the innate and adaptive immune responses. In order to investigate whether avian defensins could activate monocytes of another species, and whether chicken defensins could modulate or amplify the adaptive immune responses of murine through the TLR-NF-kappaB pathway, the relationship between the chicken intestinal defensin AvBD13 and TLR4 in murine peripheral blood mononuclear cells (PBMCs) was explored in vitro. Monocytes were stimulated with AvBD13 (1 microg/mL). The levels of NF-kappaB p65, CD80, CD86, IL-12 and IFN-alpha were measured by immunohistochemical analysis of the cells or enzyme-linked immunosorbent assay (ELISA), and the TLR4 levels in monocytes were measured by flow-cytometry. We found that AvBD13 can activate NF-kappaB, induce the inflammatory cytokines IL-12 and IFN-alpha, and upregulate costimulatory molecules like CD80 and monocyte proliferation, which was clearly inhibited by the anti-TLR4 antibody. TLR4 expression was rapidly downregulated in the presence of AvBD13. AvBD13 could modulate monocytes directly and serve as an endogenous ligand for TLR4 and upregulate costimulatory molecules and monocyte proliferation. Thus, TLR4 is involved in AvBD13-mediated activation of adaptive immune responses.