Seroprevalence and Risk Factors of Toxoplasma gondii Infection in Farmed Minks (Neovison vison) in Northeastern and Eastern China

An adenovirus-vectored vaccine based on the N protein of feline coronavirus elicit robust protective immune responses

Feline coronavirus (FCoV) is an unsegmented, single-stranded RNA virus belonging to the Alphacoronavirus genus. It can cause fatal feline infectious peritonitis (FIP) in cats of any ages. Currently, there are no effective prevention and control measures to against FCoV. In this study, we developed a recombinant adenovirus vaccine, AD5-N, based on the nucleocapsid(N) protein of FCoV. The immunogenicity of AD5-N was evaluated through intramuscular immunization in 6-week-old Balb/c mice and 9-12 months old cats. Compared to the control group, AD5-N specifically induced a significant increase in IgG and SIgA levels in the vaccinated mice. Furthermore, AD5-N not only effectively promoted strong cellular immune responses in cats but also induced high levels of specific SIgA, effectively helping cats resist FCoV infection. Our findings suggest that adenovirus vector vaccines based on the N gene have the potential to become candidate vaccines for the prevention and control of FCoV infection.

Novel study on the prevalence of Trichinella spiralis in farmed American minks (Neovison vison) associated with exposure to wild rats (Rattus norvegicus) in China

Minks and brown rats are reservoir hosts for many endoparasites including those of the genus Trichinella, a group of parasite nematodes with a worldwide distribution. However, little is known about the prevalence of Trichinella sp. infection in the American mink (Neovison vison) and rats (Rattus norvegicus) in China. Therefore, we aimed to examine the prevalence of Trichinella sp. infection in farmed minks in Weihai city, Shandong province, China and infer the possible route for Trichinella transmission to farmed American minks. In total, 289 muscle samples from minks and 102 carcasses of rats were collected from Weihai City. The appearance of Trichinella sp. was examined using the pooled artificial HCl-pepsin digestion method. The results showed that muscle larvae were detected in 20 of 289 minks (6.92%) and 2 of 102 synanthropic rats (1.96%). The larval density of Trichinella sp. in mink samples ranged from 0.025 to 0.815 larvae per gram (lpg), while the average larval burden in rats was 0.17 lpg. The isolates derived from minks and rats were identified at the species level using multiplex polymerase chain reaction (PCR), which revealed that the size of the two PCR products matched that of T. spiralis at 173 bp. Furthermore, sequence analysis showed 100% identity of the 5S rDNA inter-gene spacer regions of the two isolates to that of T. spiralis. This study presents a novel report of T. spiralis-mediated infection in minks and synanthropic rats in China. We highlight the vulnerability of farmed minks to Trichinella infection through exposure to synanthropic rats, which may raise a public health concern of potential zoonotic risks for domestic animals.

Recent epidemiologic and clinical Toxoplasma gondii infections in wild canids and other carnivores: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. The present review summarizes worldwide information on the prevalence of clinical and subclinical infections, epidemiology, diagnosis, and genetic diversity of T. gondii in wild canids and other carnivores for the past decade. Seroprevalence estimates of T. gondii worldwide were tabulated for each host. Seroprevalence in wild foxes was very high compared with farmed Arctic foxes. Economic and public health aspects of some of the carnivore species raised for fur and meat (raccoon dogs, mink) are discussed. Diagnostic efficacies of different serological methods and PCR methods are discussed. Clinical toxoplasmosis was observed mainly in carnivores concurrently infected with immunosuppressive Canine Distemper Virus infection. Abortion and blindness were noted in mink. Genetic diversity of isolates using DNA derived from 162 (89 viable T. gondii isolates and 73 DNA extracted from tissues) of wild carnivores from several countries is discussed. However, 69 of the 162 T. gondii isolates were strains from USA and these were genetically diverse with predominance of ToxoDB genotypes #4 and #5 (haplogroup 12). Only limited information is available concerning genotyping of T. gondii isolates from other countries; none of the 93 T. gondii isolates from other countries (Brazil, China, France, Grenada) were haplogroup 12.

Seroprevalence and risk factors of Toxoplasma gondii infection in domestic raccoon dogs in four provinces in northern China

Toxoplasma gondii is an obligate intracellular apicomplexan parasite that can infect almost all homoiothermal animals, including domestic raccoon dogs (Nyctereutes procyonoides). However, related reports on T. gondii infection in domestic raccoon dogs were limited in China. Therefore, a serological investigation was undertaken to investigate the seroprevalence and risk factors for T. gondii infection in domestic raccoon dogs. A total of 962 serum samples were collected from Jilin, Liaoning, Heilongjiang and Hebei provinces, northern China between April 2016 and November 2017, and were detected by the indirect hemagglutination test (IHA). The seroprevalence of T. gondii infection was 7.28% in the overall surveyed raccoon dogs by IHA, which was different among the four provinces ranging from 6.54% to 7.57%. The seroprevalence of T. gondii infection in male and female raccoon dogs was 6.62% and 7.79%, respectively. Based on statistical analysis, age was regarded as an important risk factor for T. gondii infection in raccoon dogs in this study (P < 0.05). This study reported the seroprevalence and risk factors of T. gondii infection in domestic raccoon dogs in northern China, which provided essential data for prevention and control of T. gondii infection in raccoon dogs in Jilin province, Liaoning province, Heilongjiang province and Hebei province.

Seroprevalence and Risk Factors of Chlamydia abortus Infection in Goats in Hunan Province, Subtropical China

Chlamydia abortus is an obligate intracellular Gram-negative bacteria, which can infect animals and human, including goats. However, little information on C. abortus infection is available in goats in Hunan province, subtropical China. To investigate the seroprevalence and risk factors of C. abortus infection in goats in Hunan province, China, a total of 911 goat blood samples were collected randomly from 14 herds having number of goats ranging from 1000 to 3000 from March 2014 to December 2015. Seropositive animals were found in 11 out of 14 (78.57%) goat herds with seroprevalence ranging from 0.00% to 29.94% in individual herds. Overall, the seroprevalence of C. abortus infection was different among regions (southern Hunan: 1.78%; northeast Hunan: 5.47%; and west Hunan: 15.29%), gender (male: 4.58% and female: 9.10%), seasons (spring: 5.97%; summer: 2.61%; autumn: 16.88%; and winter: 10.94%), and ages (year ≤1: 2.39%; 1 < year ≤2: 9.58%; 2 < year ≤3: 9.16%; and year >3: 17.57%). Risk factors for C. abortus infection were associated with region, season, and age in this study. To our knowledge, this is the first document to demonstrate the existence of C. abortus infection in goats, and the seroprevalence was 8.45% out of 911 goats in Hunan province.

Seroprevalence and Risk Factors of Toxoplasma gondii Infection in Farmed Raccoon Dogs (Nyctereutes procyonoides) in China

Toxoplasma gondii, an obligate intracellular apicomplexan parasite, can infect homoiothermal vertebrate animals, including raccoon dogs (Nyctereutes procyonoides). Regretfully, data on T. gondii infection in raccoon dogs were limited in China. Therefore, to investigate the seroprevalence and to evaluate risk factors for T. gondii infection in raccoon dogs, a total of 1181 raccoon dog blood samples were collected from Jilin and Shandong provinces, China, from September to December 2014. The antibodies of T. gondii were examined using the modified agglutination test. Overall, the seroprevalence of T. gondii infection was 8.64% in the examined raccoon dogs. The prevalences of T. gondii infection were different among cities (ranging from 2.96% in Yantai to 17.62% in Qingdao), genders (female: 7.58%; male: 9.22%), and ages (young: 8.53%; subadult: 7.71%; adult: 7.73%). Region was considered as an important risk factor for T. gondii infection in this study. This is the first report of T. gondii infection in raccoon dogs in China, providing baseline information for prevention and control of T. gondii infection in raccoon dogs in Jilin and Shandong provinces, China.