Isolation and characterization of Toxoplasma gondii from captive caracals (Caracal caracal)

Abstract

Toxoplasma gondii infects most warm-blooded animals, including humans. Felids can serve as both intermediate and definitive hosts for T. gondii . However, there is no direct evidence to prove the caracal ( Caracal caracal ) is an intermediate host for T. gondii . Here, we report T. gondii infection in two caracals in a zoo from China. Antibodies against T. gondii were found in both caracals by modified agglutination test (MAT) (cut-off titer: 1:25). Tissue cysts were observed in the leg and tongue muscles of caracal case # 1. These cysts were confirmed as T. gondii by immunohistochemical staining and T. gondii was detected by polymerase chain reaction (PCR). Viable T. gondii strain was isolated from the striated muscles of caracal case # 2 and designated as TgCaracalCHn1. DNA from tachyzoites obtained from cell cultures was characterized by RFLP-PCR using ten markers ( SAG1, SAG3, SAG2, BTUB, c22-8, GRA6, c29-2, PK1, L358, and Apico ) and the virulence genes ( ROP5 and ROP18 ). The results indicate that this isolate belongs to ToxoDB genotye #2 (Type III). The virulence of this isolate was evaluated in BALB/c mice. A dose of 10 4 TgCaracalCHn1 tachyzoites was non-lethal to mice. Tissue cysts were found in brain tissues of infected mice. This result confirmed that the TgCaracalCHn1 is non-virulent to mice. Current study documents first isolation of viable T. gondii strain from caracal and also indicates that caracal can act as new intermediate host for T. gondii .

Isolation, genotyping and virulence determination of aToxoplasma gondiistrain from non‐human primate from China

“…This finding indicates that T. gondii oocysts contaminate the habitat of these monkeys. The high seropositivity and isolated viable of T. gondii in captive tigers, serval, caracals, white spoonbills and sheep from Central China support this hypothesis (Dong et al., 2019; Jiang et al., 2020a, 2020b; Yang et al., 2019, 2020). It should not be ignored that T. gondii tachyzoites were recovered from the bronchoalveolar lavages of T. gondii ‐inoculated squirrel monkeys and that T. gondii may be horizontally transmitted by aerosol between infected monkeys and cage mates (Furuta et al., 2001).…”

“…Previous studies have identified ToxoDB#9 ( Chinese 1 ), ToxoDB#2, ToxoDB#4, ToxoDB#20, ToxoDB#17, ToxoDB#292 T . gondii genotypes in animals from Central China, ToxoDB#9 and ToxoDB#2 were the predominant genotypes in China (Dong et al., 2019; Jiang et al., 2020a, Jiang et al., 2020b; Su et al., 2019; Yang et al., 2015, 2019). ToxoDB#3 and mixed infections were identified in a ring‐tailed lemur and a squirrel monkey from China (Huang et al., 2018; Yang et al., 2017).…”

Additional evidence of tigers (Panthera tigris altaica) as intermediate hosts for Toxoplasma gondii through the isolation of viable strains

“…ToxoDB#2 (type III) is widely distributed worldwide, including Asia, Africa, South Europe, North America, South, and Central America ( Chaichan et al, 2017 ; Dubey, 2010 ; Dubey et al, 2013 , 2014 ; Shwab et al, 2018 ). ToxoDB#2 T. gondii strains have been found in cats ( Yang et al, 2015 ), lambs ( Jiang et al, 2020a ), caracal ( Jiang et al, 2020b ), white Spoonbill ( Yang et al, 2020 ), and kangaroo ( Yang et al, 2023 ) from central China, all of them were 3/3 for ROP18/ROP5 and most of them were avirulence for mice (except TgRooCHn3). They share the same genotype, and ROP18/ROP5 allele, this indicates that TgTigerCHn4 may be of local origin.…”

Unifying Virulence Evaluation in Toxoplasma gondii: A Timely Task

“…a ROP18/5 allele combination and CS3 profile are considered to have predictive value for the virulence in mice ( Pena et al., 2008 ; Shwab et al., 2016 ); isolates with low passage history ( Khan et al., 2014 ). b Morbidity scoring and humane endpoint ( Pena et al., 2021 ); tabulation of data ( Jiang et al., 2020 ); LD 50 calculations (Probit tests). c Virulence classification ( Su et al., 2002 ; Dubey et al., 2014 ; Saraf et al., 2017 ).…”

“…Another useful way to measure parasite transmissibility is to evaluate parasite cystogenesis, the capacity and capability of T. gondii to form tissue cysts. The central nervous system (CNS) is the tissue par excellence to study the development of cysts during the chronic phase of the infection but the T. gondii tropism towards immune privileged organs also involves ocular or muscle tissues ( Jiang et al., 2020 ; Yang et al., 2020 ; Dubey, 2021 ). Cysts can be quantified and even measured (diameter) by microscopic observation of fresh/unstained ( Dubey et al., 2012 ) and immunostained fixed brain sections or brain homogenates ( Masatani et al., 2020 ; Wang and Sibley, 2020 ).…”