Wei-Li Wang

Isolation of active compounds from methanol extracts of Toddalia asiatica against Ichthyophthirius multifiliis in goldfish (Carassius auratus)

The parasitic ciliate Ichthyophthirius multifiliis infests all species of freshwater fish and can cause severe economic losses in fish breeding. The present study aims to evaluate the antiparasitic activity of the active components from Toddalia asiatica against I. multifiliis. Bioassay-guided fractionation and isolation of compounds with antiparasitic activity were performed on the methanol extract of T. asiatica yielding two bioactive compounds: chelerythrine and chloroxylonine identified by comparing spectral data (NMR and ESI-MS) with literature values. Results from in vitro antiparasitic assays revealed that chelerythrine and chloroxylonine could be 100% effective against I. multifiliis at the concentration of 1.2 mg L(-1) and 3.5 mg L(-1), with the median effective concentration (EC50) values of 0.55 mg L(-1) and 1.90 mg L(-1) respectively. In vivo experiments demonstrated that fish treated with chelerythrine and chloroxylonine at the concentrations of 1.8 and 8.0 mg L(-1) carried significantly fewer parasites than the control (P<0.05). The acute toxicity (LC50) of chelerythrine for goldfish was 3.3 mg L(-1).

Seroprevalence of Toxoplasma gondii antibodies and associated risk factors among children in Shandong and Jilin provinces, China

OBJECTIVE Infection by the protozoan parasite Toxoplasma gondii is generally prevalent in animals and humans worldwide. However, little is known about T. gondii infection among children in China. Thus, the present study was conducted to detect the seroprevalence of T. gondii infection and estimate associated risk factors among children in eastern China. METHODS A cross-sectional study of 1500 children from three cities (Changchun, Qingdao, Weihai) was conducted between May 2013 and July 2014 to estimate the seroprevalence and potential risk factors associated with acquiring T. gondii infection in children in China. Demographic and blood samples were collected, and anti-T. gondii IgG and IgM antibodies were measured by ELISA. RESULTS The mean age of the 1500 children participating in the study was 9.03 years (range 1-18). The overall seroprevalence of Toxoplasma infection was 15.13%, of which 13.13% were positive for only anti-Toxoplasma IgG antibodies, 3.13% were positive for both anti-Toxoplasma IgG and IgM antibodies and 2.00% were IgM positive and IgG negative. Moreover, raising cats at home (OR=1.94, 95% CI=1.288-2.912, P=0.002) and hand washing habits (OR=0.38, 95% CI=0.230-0.635, P<0.001) were estimated to be risk and protective factors associated with Toxoplasma seroprevalence, respectively. CONCLUSIONS The present study revealed for the first time that childrens infection with T. gondii is common in eastern China. The present data indicate a need to implement methods of prevention and control measures against Toxoplasma infection in China.

Seroprevalence and risk factors of hepatitis E virus infection among children in China

Hepatitis E virus (HEV) infection is an important public health concern worldwide, especially in developing countries, causing waterborne outbreaks as well as sporadic autochthonous hepatitis. China is usually considered to be a HEV‐endemic area, but the prevalence of HEV infection in children in mainland China remains unclear. Between May 2013 and July 2014, a cross‐sectional study was conducted to estimate the seroprevalence and potential risk factors associated with the acquisition of HEV infection by children in China. A total of 1,500 healthy children (range 1–18; 942 and 558 from urban and rural areas, respectively) were recruited to examine for the presence of anti‐HEV IgG and IgM antibodies by enzyme‐linked immunosorbent assay. Socio‐demographic and behavioral characteristics from the examined children were obtained. The overall seroprevalence of HEV in the examined children was 14.93%. Of these, 174 (11.60%) were positive for only anti‐HEV IgG antibodies, 50 (3.33%) were IgM positive and IgG negative, and 44 (2.93%) were positive for both anti‐HEV IgG and IgM antibodies. Age, type of residence area, contact with pigs, and source of drinking water were found to be associated with HEV infection. These findings demonstrated the high prevalence of HEV and the considerable potential for the transmission of HEV infection in children in China. J. Med. Virol. 87:1573–1577, 2015.

Seroprevalence of and risk factors for Neospora caninum infection in yaks (Bos grunniens) in China

The aim of the present study was to detect the seroprevalence of Neospora caninum infection in yaks in Gansu province, China. Serum samples from 974 white yaks and 610 black yaks were tested by a commercial competitive-inhibition ELISA for the detection of specific anti-N. caninum antibodies.; N. caninum antibodies were detected in 10.4% of yaks with higher prevalence in black (11.5% of 610) than white yak (8.6% of 974). Age, regions and sampling times were considered as risk factors associated with N. caninum infection. These results revealed the seroprevalence of N. caninum in white yaks for the first time in China.

Seroprevalence of Neospora caninum infection in farmed sika deer (Cervus nippon) in China.

Neospora caninum is a worldwide protozoan that can induce neuromuscular disease in dogs and reproductive failure in domestic and wild ruminants. The objective of the present investigation was to determine the seroprevalence of N. caninum infection in farmed sika deer in China as little is known of this host-parasite relationship. A total of 1800 serum samples were collected during 2013 and 2014 from farmed sika deer in the major production areas of Liaoning, Jilin and Heilongjiang provinces.Assay by ELISA for N. caninum antibodies indicated a seroprevalence of 13.6% in 2013 and 15.8% in 2014, varying in different regions from 9.5% to 27.5%. Statistical analysis revealed that prevalence in animals aged >4 years (20.4%) was significantly higher than in the age ranges <2 years (9.6%) and 2-4 years (11.4%) (P<0.01). Moreover, sika deer in herds with a history of miscarriage (41.9%) had a significantly higher seroprevalence than in those without (12.6%) (P<0.01). The present survey confirms that N. caninum does occur in farmed sika deer in China and provides base-line data for the design and evaluation of measures for its control and prevention in this host.

Coxiella burnetii (Q fever) Infection in Farmed Ruminants in Three Northeastern Provinces and Inner Mongolia Autonomous Region, China.

Coxiella burnetii is the pathogenic agent of Q fever, a zoonosis that occurs worldwide. In China, the organism infects people and a wide range of wild and farmed animals. However, little is known about C. burnetii infection in farmed ruminants in northeastern China, and there appears to have been no previous study on sika deer. The present study was conducted to determine the seroprevalence of C. burnetii in farmed ruminants in this region of China. A total of 3147 domestic ruminants (784 sheep, 1016 cattle, and 1347 sika deer) were randomly collected for this study. An indirect enzyme-linked immunosorbent assay kit was used to detect the antibodies to C. burnetii. The results showed an overall seroprevalence of 16.7% in domestic ruminants (24.9%, 13.5%, and 12.3% in cattle, sheep, and sika deer, respectively). This is the first report of C. burnetii seroprevalence in sika deer in China. Protective and hygiene measures should be applied in farm management to reduce the risk of exposure of C. burnetii to humans.

Seroprevalence of Encephalitozoon cuniculi and Toxoplasma gondii in domestic rabbits (Oryctolagus cuniculus) in China

The breeding of domestic rabbits (Oryctolagus cuniculus) for human consumption has a long tradition in China. Infections that can affect the production of meat or even be transmitted from animals to humans are important to monitor, especially for public health reasons as well as for their impact on animal health. Thus, a total of 1,132 domestic rabbit sera from 4 regions in China were collected for serological screening for Encephalitozoon cuniculi and for Toxoplasma gondii by ELISA and modified agglutination test (MAT), respectively. Antibodies to E. cuniculi were detected in 248/1,132 (21.9%) sera tested while antibodies against T. gondii revealed a seroprevalence of 51/1,132 (4.5%). We believe that the present results are of epidemiological implications and public health importance due to the acknowledged susceptibility of humans to E. cuniculi and T. gondii infections. Therefore, routine screening tests of domestic rabbits are proposed considering the zoonotic potential of these parasites.

Differential expression of ATP-dependent RNA helicase gene in viable but nonculturable Salmonella pullorum

The purpose of this study was to screen new gene involved in viable but nonculturable (VBNC) Salmonella using messenger ribonucleic acid (mRNA) differential display. Strain cultured on liquid lysogeny broth (LB) medium at 4°C was induced for VBNC state; activated genes were detected using mRNA differential display and differential fragment of adenosine triphosphate (ATP)-dependent RNA helicase rh1B gene was verified. The fragment coded adenosine triphosphatase (ATPase) structure domain of DEAD-box helicase. The screened fragment which codes ATPase structure domain of DEAD-box helicase may be a candidate marker for VBNC Salmonella detection. Key words : Viable but nonculturable, Salmonella , ATP-dependent RNA helicase.

Prevalence of Neospora spp. in donkeys in China

This study was conducted to detect specific anti-Neospora antibodies using a commercial competitive-inhibition ELISA kit, and to evaluate the risk factors for Neospora spp. infection. Out of a total of 2,228 donkey sera collected in three provinces in China, 211 (9.5%) were found to be positive for anti-Neospora antibodies. Statistical analysis revealed that age (p = 0.019, OR = 1.62, 95%CI: 1.08-2.44), feeding status (p < 0.001, OR = 3.79, 95%CI: 2.65-5.43), miscarriage history (p = 0.006, OR = 2.56, 95%CI: 1.27-4.01), and contact with dogs (p < 0.001, OR = 2.69, 95%CI: 1.86-3.88) were significant risk factors for Neospora spp. infection. This is the first evidence of Neospora infection in donkeys in China.

A TaqMan-based real-time PCR assay for the detection of Ungulate bocaparvovirus 2

Ungulate bocaparvoviruses (UBoV) 2-5 are recently discovered porcine bocaparvoviruses belonging to the family Parvoviridae, and are considered to be a potentially major cause of swine diseases. In order to detect local UBoV2 epidemics in China, we developed a TaqMan-based real-time PCR (qPCR) assay targeting the UBoV2 VP1 gene and compared the results of qPCR with conventional PCR (cPCR). The qPCR reproducibly detected a recombinant DNA plasmid containing the VP1 gene over a range of eight orders of magnitude, from 9.97 × 10-1-106 copies/μL, with a lower limit of detection of 9.97 copies/μL, compared with approximately 9.97 × 102 copies/μL for cPCR. The qPCR assay showed no cross-reactivity with other UBoVs or other porcine viruses. This qPCR assay detected UBoV2 in 18.1% (84/463) of pig samples collected from Chinese swine herds, with the highest infection rate of 35.3% (53/150) in loose stools. UBoV2 was not detected in liver samples. The TaqMan-based qPCR assay established in this study was highly sensitive and specific for the diagnosis and quantification of UBoV2. The results of this study will further our understanding of the etiology, epidemiology, and pathogenesis of UBoV2 infection.