Evidence of red panda as an intermediate host of Toxoplasma gondii and Sarcocystis species

Barriers and corridors: Assessment of gene flow and movement among red panda populations in eastern Himalayas

Landscape features can impede dispersal, gene flow, and population demography, resulting in the formation of several meta-populations within a continuous landscape. Understanding a species' ability to overcome these barriers is critical for predicting genetic connectivity and population persistence, and implementing effective conservation strategies. In the present study, we conducted a fine-scale spatial genetic analysis to understand the contemporary gene flow within red panda populations in the Eastern Himalayas. Employing geometric aspects of reserve design, we delineated the critical core habitats for red pandas, which comprise 14.5 % of the landscape (12,189.75 Km2), with only a mere 443 Km2 falling within the protected areas. We identified corridors among the core habitats, which may be vital for the species' long-term genetic viability. Furthermore, we identified substantial landscape barriers, including Sela Pass in the western region, Siang river in the central region, and the Dibang river, Lohit river, along with Dihang, Dipher, and Kumjawng passes in the eastern region, which hinder gene flow. We suggest managing red panda populations through the creation of Community Conservation Reserves in the identified core habitats, following landscape-level management planning based on the core principles of geometric reserve design. This includes a specific emphasis on identified core habitats of red panda (CH-RP 5 and CH-RP 8) to facilitate corridors and implement meta-population dynamics. We propose the development of a comprehensive, long-term conservation and management plan for red pandas in the transboundary landscape, covering China, Nepal, and Bhutan.

Gut commensal bacteria exacerbate toxoplasmosis associated with TgSheepCHn5 (ToxoDB#2) and TgRedpandaCHn1 (ToxoDB#20) through Th1 immune response

Oral infection of mice with several strains of Toxoplasma gondii results in intestinal pathological lesions, which contributes to the invasion of this parasite. However, the exact mechanism is unclear, and only a few strains have been explored. Here, T. gondii TgSheepCHn5 and TgRedpandaCHn1 strains from sheep and red panda were evaluated. The TgSheepCHn5 and TgRedpandaCHn1 strains induced intestinal lesions, loss of Paneth cells, and gut commensal bacteria dysbiosis in Swiss Webster mice. The lesions and loss of Paneth cells were dependent on IFN-γ and gut commensal bacteria during T. gondii infection. Deleting IFN-γ or gut commensal bacteria suppressed the Th1 immune response, alleviated the lesions and parasite loading, and upregulated the number of Paneth cells. Loss of IFN-γ production accelerated mice death, whereas the deletion of gut commensal bacteria enhanced the survival time of the host. The Th1 cell immune responses have positive and negative effects on toxoplasmosis, resistance to T. gondii infection, and acceleration intestine lesions. Adjustment of Th1 cell responses and gut commensal bacteria may be effective treatments for toxoplasmosis.

Isolation and Genetic Characterization of Toxoplasma gondii from a Patas Monkey (Erythrocebus patas) in China

Many cases of Toxoplasma gondii infection have been reported worldwide in non-human primates (NHPs), especially in captive New World monkeys. However, few studies on toxoplasmosis in Old World monkeys have been conducted. In this study, serological and molecular biological analyses were carried out to look for T. gondii antibodies and T. gondii infection in 13 NHPs from China. T. gondii infection was confirmed in 8 NHP cases. T. gondii antibodies were detected in 1/5 New World monkeys and in 4/7 Old World monkeys. T. gondii DNA was detected in 3/5 New World monkeys and 5/7 Old World monkeys. The one ring-tailed lemur was negative for both antibodies and DNA of T. gondii. The most common clinical manifestations of T. gondii infection were malaise, poor appetite, emaciation, and foamy nasal discharge. The most common histopathological findings were interstitial pneumonia, necrotic hepatitis, necrotizing myocarditis, lymphadenitis, and necrotic splenitis. One viable T. gondii strain was successfully isolated from the myocardium of a patas monkey (Erythrocebus patas) by bioassay in mice. T. gondii tachyzoites were obtained from cell cultures and were designated as TgMonkeyCHn2. The genotype of this strain belongs to ToxoDB genotype #9, and the allele of ROP18/ROP5 gene was 3/6. TgMonkeyCHn2 tachyzoites were avirulent in Swiss mice. To our knowledge, this is the first report of fatal toxoplasmosis in a patas monkey. T. gondii infection in patas monkeys may indicate environmental contamination by oocysts. The patas monkey is a new host record for T. gondii.

Seroprevalence and risk factor analysis of Toxoplasma gondii infection in Siberian tigers (Panthera tigris altaica) and giant pandas (Ailuropoda melanoleuca) in China

Toxoplasmosis, caused by Toxoplasma gondii, is a worldwide zoonosis. The aim of the present study was to detect the seroprevalence of T. gondii infection and associated risk factors among Siberian tigers (Panthera tigris altaica) and giant pandas (Ailuropoda melanoleuca) in China. Blood samples from 112 Siberian tigers and 22 giant pandas were tested for immunoglobulin G (IgG) against T. gondii by enzyme-linked immunosorbent assay (ELISA). The seroprevalence of T. gondii infection was 7.14% among Siberian tigers and 9.09% among giant pandas. No risk factors were found to be significantly associated with seroprevalence (P > 0.05). This is the first study to evaluate T. gondii infection in Siberian tigers on a large scale in China, and it also updates the information regarding the positivity rate of T. gondii infection among giant pandas in China.

Reaching over the gap: A review of trends in and status of red panda research over 193 years (1827-2020)

The red panda is a unique species taxonomically known for its peculiar biological and ecological characteristics, and extreme attractiveness. Despite being highly significant from conservation, scientific and economic perspectives, this species has experienced a declining population in the wild. Thus, to direct further research priorities and conservation actions and assess gaps in the current research trend of this species, a systematic literature review was conducted covering 175 journal articles published in English over 193 years (1827-2020). This review revealed that (1) the biological aspect was highly studied compared to other thematic areas of red panda (2) captive-based studies are relatively higher than the studies based in wild populations (3) China is leading the red panda studies amongst all red panda range (4) The universities were found contributing more to red panda studies than other institutions. Surprisingly, we found that the researchers from the non-range country were leading red panda study than those from range countries. Our review highlighted the need of prioritising studies in underrepresented locations and understudied thematic areas focusing on the assessment of climate change impact, bamboo distribution status, ecosystem services of red panda habitat, behavior and movement ecology, population estimation, and metapopulation dynamics. We urge landscape-level studies and long-term population monitoring. Besides, we also suggest the documentation and evaluation of the effectiveness of ongoing red panda-focused conservation programs. We also stress the need for strengthening the capacity of institutions and people from range countries.

Comparative Immunological Response and Pathobiology of Mice Inoculated with Toxoplasma gondii Isolated from Different Hosts

Toxoplasma gondii is an obligate intracellular parasite that has a worldwide distribution and can infect almost all warm-blood animals. Serological tests are the main detection methods for T. gondii infection in animals and humans. Little is known of biological behavior, antibody responses, and virulence of T. gondii strains in mice from China. Here we document antibody responses, tissue cyst burden, and mouse virulence of T. gondii strains isolated from different hosts in China. All T. gondii strains formed tissue cysts in the brains of mice and positively correlated with the T. gondii antibody titer (R2 = 0.3345). These results should aid in the diagnosis and characterization of T. gondii isolates.

CLINICOPATHOLOGICAL FEATURES OF TOXOPLASMOSIS IN FOUR RED PANDAS (AILURUS FULGENS)

Two geriatric red pandas (Ailurus fulgens) over a 4-yr period presented with vague clinical signs including anorexia, lethargy, and difficulty ambulating. Treatment protocols using enrofloxacin, steroids, and clindamycin were unsuccessful. Necropsy examination confirmed disseminated toxoplasmosis infection in these cases, and a modified agglutination test had been positive for a prolonged period of time before one panda showed signs of disease. A review of the Red Panda Species Survival Plan pathology database revealed two additional cases of disseminated toxoplasmosis in geriatric red pandas. Many organ systems were affected, but dissemination to the brain, lungs, and liver predominated. Immunohistochemistry or polymerase chain reaction was required to confirm a diagnosis in serologically positive animals, as well as in animals in which a histological diagnosis was suspected. This case series describes the clinical and pathological features of toxoplasmosis in geriatric red pandas.