Protective immunity against Trichinella spiralis in mice elicited by oral vaccination with attenuated Salmonella-delivered TsSP1.2 DNA

Jie Feng Li,Peng Jiang,Kai Xia Guo,Xin Qi,Yue Han,Zhong Quan Wang,Xiang Chao Cheng,Jing Cui,Chuan Yu,Shu Wei Yan,Jun Jun Lei

doi:10.1186/s13567-018-0582-2

Abstract

Trichinellosis is a worldwide important food-borne zoonosis caused mainly by ingesting raw or undercooked pork infected with Trichinella spiralis larvae. The development of vaccine is needed for preventing swine from Trichinella infection to ensure pork safety. Previous studies showed that T. spiralis serine protease 1.2 (TsSP1.2) is a vaccine candidate against Trichinella infection. In this study, the complete TsSP1.2 cDNA sequences were cloned into pcDNA3.1, and the rTsSP1.2 DNA was transformed into attenuated Salmonella typhimurium strain ΔcyaSL1344. Oral vaccination of mice with Salmonella-delivered rTsSP1.2 DNA vaccine induced an obvious intestinal mucosal IgA response and a systemic Th1/Th2 immune response; the vaccinated mice showed a 33.45% reduction of intestinal adult worms and 71.84% reduction of muscle larvae after T. spiralis larval challenge. The protection might be due to the rTsSP1.2-induced production of specific anti-TsSP1.2 sIgA, IgG, IgG1/IgG2a, and secretion of IFN-γ, IL-4 and IL-10, which protected intestinal mucosa from the parasite invasion, inhibited worm development and reduced female fecundity. The results indicate that the attenuated Salmonella-delivered rTsSP1.2 DNA vaccine offers a prospective strategy for the prevention and control of animal Trichinella infection.

Highlights

Trichinellosis, an important food-borne zoonosis worldwide, is principally caused by the parasitic nematode Trichinella spiralis [1]
Sequencing results revealed that the amplified TsSP1.2 fragment consisted of 948 bp, the predicted open reading frame (ORF) encoded a protein of 315 amino acids of 35.2 kDa, with 99.58% identity to those of TsSP1.2 in GenBank (EU302800)
An amplified TsSP1.2 fragment was detected in cells transfected with pcDNA3.1-TsSP1.2, but not in cells transfected with empty pcDNA3.1 and nontransfected baby hamster kidney cells (BHK)-21 cells

Summary

Introduction

Trichinellosis, an important food-borne zoonosis worldwide, is principally caused by the parasitic nematode Trichinella spiralis [1]. T. spiralis infection is acquired mainly from ingesting raw or semi-cooked meat contained with the encapsulated infective muscle larvae (ML). Domestic pork is a major source of this infection in southern America, Southeast Asia, China and other countries [2,3,4,5]. In China, 12 trichinellosis outbreaks caused by eating contaminated pork were recorded from 2004 to 2009 [6]. Trichinella infection in domestic pigs has a serious impact on meat safety and public health [7]. Because a large amount of pork was consumed in the world, the

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Conclusion