Oral vaccination with Trichinella spiralis DNase II DNA vaccine delivered by attenuated Salmonella induces a protective immunity in BALB/c mice

Xin Qi,Ge Ge Sun,Peng Jiang,Xin Yue,Shao Rong Long,Hua Nan Ren,Chuan Yu,Jing Cui,Yue Han,Zhong Quan Wang,Xiang Chao Cheng

doi:10.1186/s13567-018-0614-y

Xin Qi, Ge Ge Sun + Show 9 more

Open Access

https://doi.org/10.1186/s13567-018-0614-y

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Abstract

Trichinellosis is one of the most serious foodborne parasitic zoonosis with worldwide distribution, and it is necessary to develop a vaccine to interrupt transmission from animals to humans. Trichinella spiralis adult-specific DNase II-1 (TsDNase II) were identified by immunoproteomics in surface or excretory/secretory proteins of adult worms (AW) and intestinal infective larvae (IIL). The aim of this study was to investigate the systemic, mucosal responses and immune protection elicited by oral vaccination with TsDNase II DNA vaccine delivered by attenuated Salmonella typhimurium strain⊿cyaSL1344. Oral vaccination with TsDNase II DNA vaccine triggered an obvious mucosal sIgA response and a systemic IgG response in mice, and IgG1 was predominant. Th1 (IFN-γ) and Th2 (IL-4, 10) cytokines were distinctly increased in the spleen and mesenteric lymph node (MLN) cells of vaccinated mice. An indirect immunofluorescent test revealed that native TsDNase II is present at the cuticle of this nematode after the 2nd molting, further confirming that TsDNase II is adult-specific and expressed at AW and pre-adult stages. Oral immunization of mice with TsDNase II exhibited a 53.85% reduction in AW and a 59.26% reduction in ML after larval challenge. The in vitro NBL production of adult females from TsDNase II-vaccinated mice was also reduced in comparison with pcDNA3.1 or the PBS control group (P < 0.01). Our results show that oral immunization of mice with TsDNase II produced an intestinal and systematic concurrent Th1/Th2 immune response, and a significant immune protection against challenge.

Highlights

Trichinellosis, one of the important zoonotic parasitic diseases worldwide, principally results from eating raw or semi-cooked meat containing Trichinella larvae [1]
By using anti-rTsDNase Trichinella spiralis adult-specific DNase II-1 (II) serum, we detected a green fluorescence staining in pcDNA3.1-TsDNase II transfected cells, but no positive staining was detected in pcDNA3.1 control cells (Figure 1)
The results reveal that the TsDNase II mRNA was detected in tissues of mice vaccinated with TsDNase II DNA, but not in the mice receiving only empty pcDNA3.1 or PBS (Figure 2)

Summary

Introduction

Trichinellosis, one of the important zoonotic parasitic diseases worldwide, principally results from eating raw or semi-cooked meat containing Trichinella larvae [1]. After the encapsulated muscle larvae (ML) are liberated from contaminated meat in the host’s stomach, the ML migrate to the intestine and are activated into intestinal infective larvae (IIL), which invade the intestinal columnar epithelium and develop into adult worms (AW) after four moltings. From the beginning of about 5 days post-infection (dpi), female adults give birth to newborn larvae (NBL) that penetrate into the intestinal. The NBL invade and encapsulate in the host’s skeletal muscle to complete its life cycle [11]. The intestinal mucosa is the primary interaction place of the nematode with the host and the first natural barrier for combating Trichinella infection. The local intestinal mucosal immune response is important for immune protection against enteral Trichinella infection [12,13,14,15]

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