Molecular characterization of a Trichinella spiralis serine proteinase

Abstract

The aim of this study was to investigate the biological characteristics and functions of a Trichinella spiralis serine proteinase (TsSerp) during larval invasion and development in the host. The full-length TsSerp cDNA sequence was cloned and expressed in Escherichia coli BL21. The results of RT-PCR, IFA and western blotting analyses showed that TsSerp was a secretory protein that was highly expressed at the T. spiralis intestinal infective larva and muscle larva stages and primarily located at the cuticle, stichosome and intrauterine embryos of the parasite. rTsSerp promoted the larval invasion of intestinal epithelial cells (IECs) and the enteric mucosa, whereas an anti-rTsSerp antibody impeded larval invasion; the promotion and obstruction roles were dose-dependently related to rTsSerp and the anti-rTsSerp antibodies, respectively. Vaccination of mice with rTsSerp elicited a remarkable humoral immune response (high levels of serum IgG, IgG1/IgG2a, IgE and IgM), and it also triggered both systemic (spleen) and local intestinal mucosal mesenteric lymph node (MLN) cellular immune responses, as demonstrated by a significant elevation in Th1 cytokines (IFN-γ) and Th2 cytokines (IL-4) after the spleen and MLN cells from vaccinated mice were stimulated with rTsSerp. Anti-TsSerp antibodies participated in the killing and destruction of newborn larvae via ADCC. The mice vaccinated with rTsSerp exhibited a 48.7% reduction in intestinal adult worms and a 52.5% reduction in muscle larvae. These results indicated that TsSerp participates in T. spiralis invasion and development in the host and might be considered a potential candidate target antigen to develop oral polyvalent preventive vaccines against Trichinella infection.

Disruption of Epithelial Barrier of Caco-2 Cell Monolayers by Excretory Secretory Products of Trichinella spiralis Might Be Related to Serine Protease

“…However, these glycoproteins were verified to be serine proteases ( Romaris et al, 2002 ). Furthermore, r Ts Serp has been reported to help larvae invade IECs during infection ( Yue et al, 2020 ). Therefore, it is likely that serine proteases act on TJ proteins to achieve the intestinal barrier disruption.…”

Specific binding of aspartic protease and enterocytes promotes Trichinella spiralis invasion of murine intestinal epithelium cells

“…Vaccination of mice with rTsASP2 also induced the significant protection, as intestinal adult worms, NBL production and muscle larval burden in vaccinated mice was distinctly reduced. The immune protection (e.g., muscle larval burden reduction) induced by vaccination of rTsASP2 could be comparable with that of several recombinant T. spiralis proteins, such as cathepsin B (50.90%; Cui et al, 2019), serine protease (52.10%; Sun et al, 2018a), serine proteinase (52.50%; Yue et al, 2020), peptidase (41.93%; Lei et al, 2020), elastase-1 (64.06%; , and TsASP1 (60.50%; Xu et al, 2021). The reduction of the worm burden might be related with the Th1/Th2 immune response which may interrupt larval invasion of enterocytes, impair larval establishment and development in enteric epithelium (McVay et al, 2000;Song et al, 2018b).…”

“…The first group of mice was immunized subcutaneously with 20 μg of rTsASP2 emulsified in ISA201 adjuvant and two booster immunization was performed using the same method at a 2-week-interval. Other three groups were subcutaneously immunized with MBP protein emulsified in ISA201, only ISA20 adjuvant or PBS alone using the same vaccination scheme (Long et al, 2014;Yue et al, 2020). To evaluate the induced systemic responses, serum samples were collected from vaccinated mice at weeks 0, 2, 4 and 6 after immunization.…”

Characterization of a Novel Glutamine Synthetase From Trichinella spiralis and Its Participation in Larval Acid Resistance, Molting, and Development

“…After washes with PBS, the worms were stained using goat anti-mouse IgG-FITC conjugate (1:100; Santa Cruz, United States). Following washes again, whole worms and cross-sections were examined under a fluorescence microscope (Olympus, Tokyo, Japan) ( Lei et al, 2020 ; Yue et al, 2020 ).…”