Animals and parasites

T. spiralis stains were identified by OIE Collaborating Center on Foodborne Parasites in Asian-Pacific Region in August 2014 and maintained in Institute of Zoonoses, Jilin University. Female C57BL/6 mice, 6–8 weeks old, were purchased from Jilin University experimental animal center (Jilin, China), with the certificate No. 2016–0001 in conformity of SCXK (Jilin). The muscle larvae of T. spiralis were recovered from infected mice by artificial digestion method as previously described (Friend et al. 1996).

All mice were infected with 300 muscle larvae per os. Experimental mice infected with T. spiralis were given the reported TLR3 agonist poly(I:C) (InvivoGen) 7.5 mg/kg, TLR4 agonist LPS (InvivoGen) 2 mg/kg, TLR8 agonist TL8-506 (InvivoGen) 5 mg/kg, and TLR9 agonist ONDM362 (InvivoGen) 5 mg/kg by tail vein injection at 0, 2, 5, 8, 11, 14, 17, 20, and 27, 34 days post infection (dpi). Meanwhile, the control group of mice was only injected with PBS. Parasite burden was calculated as the total number of larvae per gram (LPG) of muscle tissue at 35 dpi. The reduction percentage of LPG in the treated animals was calculated as follows: LPG reduction rate = (control group mean LPG − treated group mean LPG) / control group mean LPG × 100% (Garcia et al. 2013; Gurish et al. 2004)