Somatic soluble proteins (crude antigens) from variousT. expression pattern and distribution signature of TsTryp at various life-cycle Letermovir stages ofT. spiraliswere analyzed by quantitative PCR, western blotting and the immunofluorescence test. An ELISA with rTsTryp and ML ES antigens was used to detect immunoglobulins G and M (IgG, IgM) in serum samples of infected mice, swine and humans. The seropositive results were further confirmed by western blot with rTsTryp and ML ES antigens. == Results == TsTryp expression was observed in diverseT. spiralislife-cycle phases,with particularly high expression in the early developmental phase (intestinal infectious larvae and adults), with distribution observed mainly at the nematode outer cuticle and stichosome. rTsTryp was identified byT. spiralis-infected mouse sera and anti-rTsTryp sera. Natural TsTryp protease was SMAD2 detected in somatic soluble and ES antigens of the nematode. In mice infected with 200T. spiralisML, serum-specific IgG was first detected by rTsTryp-ELISA at 8 days post-infection (dpi), reaching 100% positivity at 12 dpi, and first detected by ES-ELISA at 10 dpi, reaching 100% positivity at 14 dpi. Specific IgG was detected by rTsTryp 2 days earlier than by ES antigens. When specific IgG was determined in serum samples from trichinellosis patients, the sensitivity of rTsTryp-ELISA and ES antigens-ELISA was 98.1% (51/52 samples) and 94.2% (49/52 samples), respectively (P= 0.308), but the specificity of rTsTryp was significantly higher than that of ES antigens (98.7% vs. 95.4%;P= 0.030). Additionally, rTsTryp conferred a lower cross-reaction, with only three serum samples in total testing positive from 11 clonorchiasis, 20 cysticercosis and 24 echinococcosis patients (1 sample from each patient group). == Conclusions == TsTryp was shown to be an early and highly expressed antigen at intestinalT. spiralisstages, indicating that rTsTryp represents a valuable diagnostic antigen for the serodiagnosis of Letermovir earlyTrichinellainfection. == Graphical Abstract == == Supplementary Information == The online version contains supplementary material available at 10.1186/s13071-023-06067-7. Keywords:Trichinellosis,Trichinella spiralistrypsin, Recombinant antigen, Serodiagnosis, ELISA == Background == Trichinellosis is an important zoonotic parasitosis caused by nematodes of the genusTrichinella. In humans,Trichinellainfection occurs through the ingestion of raw or semi-cooked meat of animals infected withTrichinellalarvae, withTrichinella spiralisthe prime causative agent [1,2]. This parasitic disease can occur worldwide, with 50 trichinellosis outbreaks reported in the European Union between 2015 and 2019 [3] and 13 trichinellosis outbreaks involving 1604 cases and 12 deaths were recorded in Southeast Asian countries from 2001 to 2021 [4]. In China, specifically, eight trichinellosis outbreaks were documented during the 20092020 period, with 479 patients and two deaths reported [5]. The consumption of undercooked pork and pork products are the predominant source ofT. spiralisinfection. Trichinellosis therefore remains a thorny challenge and threat to public health and food safety [6]. Following the ingestion ofTrichinella-infected meat, muscle larvae (ML) are liberated and develop into intestinal infectious larvae (IIL) in the small intestine, where they undergo molting 4 times to ultimately develop into adult worms (AW). Following copulation, the mature Letermovir females produce newborn larvae (NBL), which penetrate the skeletal muscles through the circulatory and lymphatic systems and develop into the encapsulated ML [7]. The clinical manifestations of trichinellosis at these different development stages differ. The initial intestinal stage of the infection is often accompanied by nonspecific gastrointestinal symptoms, including nausea, emesis, abdominal pain and diarrhea. The major symptoms and signs at the muscular stage (acute stage) are fever, periorbital edema, myalgia or muscle weakness, skin eruption, among others [8,9]. Clinical diagnosis of trichinellosis is rather difficult due to its non-pathognomonic symptomatology in the initial stage of infection, especially in sporadic cases and upon presentation of early cases of a new outbreak. Moreover, medical practitioners from non-endemic areas are usually unfamiliar with the manifestations of trichinellosis, and patients are often not taken seriously and/or misdiagnosed. The definitive diagnosis.