Insight into Trichinella britovi infection in pigs: effect of various moderate infectious doses on larvae density and spatial larvae distribution in carcasses and comparison of the detection of anti-T. britovi IgG of three different commercial ELISA tests and immunoblot assay

Abstract

Background: Given the limited information available on the T. britovi muscle larvae (ML) distribution in pigs’ muscles and humoral immune response of pigs infected with moderate doses of this parasite, this study investigated infectivity of a Polish strain of T. britovi for pigs, the antibody response of this host to moderate doses of T britovi and the efficiency of three different commercial ELISA kits and an immunoblot assay at detecting anti-T. britovi IgG.Results: No significant differences in terms of the infection level of particular muscles or of whole carcasses between pigs infected with 3000 and those infected with 5000 ML of T. britovi were observed. The highest intensity of T. britovi infection was reported in the diaphragm pillars. The larvae of T. britovi showed homogeneous distribution with respect to the muscle side. Statistically, specific IgG antibodies against ES antigens of Trichinella ML were first detected by all ELISA protocols on day 36 post infection; however, individual pig results showed some differences between the three tests applied. A significant increase in the level of anti-T. britovi IgG was observed between days 36 and 41 post infection, and from day 45 until day 62 after T. britovi infection, production of these antibodies reached its plateau phase. No positive correlation was found between the anti-T. britovi IgG level and larvae density in 15 different muscles. Sera of T. britovi-infected pigs showed reactivity with T. britovi ML ES antigens of 62, 55 and 52 kDa.Conclusions: The results provide novel information on spatial larvae distribution in muscles and the humoral immune response of pigs exposed to moderate doses of a Polish strain of T. britovi, extend knowledge on serological diagnostic tools which may be introduced in veterinary practice for the detection of T. britovi infections in pig production, and offer practical solutions for meat hygiene inspectors in the field at sampling sites when examining pigs’ carcasses for Trichinella.

Immunoproteomic Analysis of Trichinella britovi Proteins Recognized by IgG Antibodies from Meat Juice of Carnivores Naturally Infected with T. britovi

“…Unsurprisingly, there is a great interest in identifying peptide or protein biomarkers that could be used as markers to identify early Trichinella infection in humans and domestic animals (diagnostic properties) or as vaccines against Trichinella infection, e.g., in pigs (immunoprotective properties). Although recent studies have focused on the immunoreactive proteins in host serum and plasma during Trichinella infection, they have mainly been based on 2DE-electrophoresis examination coupled with LC-MS/MS, or 2DE electrophoresis followed by MALDI-TOF mass spectrometry of human, mouse, or pig samples [ 30 , 36 , 37 , 38 , 39 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ]. In contrast, the present paper employs standard 1DE electrophoresis coupled with LC-MS/MS analysis to obtain preliminary findings; it is the first proteomic analysis of proteins recognized by meat juice samples collected from wildlife.…”

“…Most studies have used serum/plasma samples to determine the protein profile characteristic of Trichinella infection [ 14 , 30 , 36 , 37 , 38 , 39 , 47 , 48 , 49 , 51 , 52 , 53 ]. However, while serum or plasma are not always available for analysis, meat juice samples provide an adequate, alternative matrix that can be easily obtained for post-mortem analysis, especially from free-living animals.…”

“…Although most trichinellosis in humans is caused by T. spiralis , some cases of T. britovi infection have recently been observed [ 54 , 55 , 56 , 57 ]. Furthermore, several papers have described the analysis of crude and excretory-secretory proteins characteristic of T. britovi [ 14 , 30 , 36 , 38 , 39 , 48 ]. These studies, conducted using human or T. britovi -infected pig serum, identified some proteins characteristic of T. britovi infection, including those that play a role in the migration of NBL in host tissue or those with immunomodulatory potential.…”

“…The aim of the present study was to determine the pattern of proteins reacting with IgG antibodies in meat juice samples collected from free-living animals infected with T. britovi . It was found that antibodies present in meat juice samples react with proteins that are associated with T. britovi infection; in addition, the majority of them appear to be involved in metabolic processes and host–parasite interaction (e.g., the mechanisms of the parasite invasion of host tissue, larval migration, larval molting, immunomodulation), such as heat shock proteins, a serine protease, paramyosin, a poly-cysteine tailed protein, and deoxyribonuclease-2-alpha [ 14 , 30 , 36 , 38 , 39 ]. The identified proteins are compared with the literature data on proteins specific to T. britovi infection in Table 2 .…”

“…Although in the domestic cycle the immune response during Trichinella infection has been widely studied in pigs, under controlled conditions with a known infection dose and species of Trichinella [ 14 , 30 , 36 , 37 , 38 , 39 ], the immunoprevalence of anti- Trichinella antibodies has been also examined in many animals species connected to the sylvatic cycle [ 13 , 24 , 26 , 40 , 41 , 42 , 43 , 44 , 45 , 46 ] as the main reservoir of Trichinella nematodes in the environment. Infections in wildlife occur in a natural way—the dose of infection, the timing, and whether they occur once or repeatedly remain unknown.…”