Detection of antibodies to Toxoplasma gondii in oral fluid from pigs

Lucía María Campero; Franziska Schott; Bruno Gottstein; Peter Deplazes; Xaver Sidler; Walter Basso

doi:10.1016/j.ijpara.2019.11.002

Detection of antibodies to Toxoplasma gondii in oral fluid from pigs

Int J Parasitol. 2020 May;50(5):349-355. doi: 10.1016/j.ijpara.2019.11.002. Epub 2019 Dec 20.

Authors

Lucía María Campero¹, Franziska Schott², Bruno Gottstein³, Peter Deplazes⁴, Xaver Sidler², Walter Basso⁵

Affiliations

¹ Institute of Parasitology, Vetsuisse-Faculty, University of Bern, Länggassstrasse 122, CH-3012 Bern, Switzerland; Immunoparasitology Laboratory, Faculty of Veterinary Sciences, National University of La Plata, 60 and 118 s/n, 1900 La Plata, Argentina; National Scientific and Technical Research Council (CONICET), Godoy Cruz, 2290, C1033AAJ Buenos Aires, Argentina.
² Department of Farm Animals, Division of Swine Medicine, Vetsuisse-Faculty, University of Zurich, Winterthurerstrasse 260, CH-8057 Zurich, Switzerland.
³ Institute of Parasitology, Vetsuisse-Faculty, University of Bern, Länggassstrasse 122, CH-3012 Bern, Switzerland.
⁴ Institute of Parasitology, Vetsuisse-Faculty, University of Zurich, Winterthurerstrasse 266a, CH-8057 Zurich, Switzerland.
⁵ Institute of Parasitology, Vetsuisse-Faculty, University of Bern, Länggassstrasse 122, CH-3012 Bern, Switzerland; Department of Farm Animals, Division of Swine Medicine, Vetsuisse-Faculty, University of Zurich, Winterthurerstrasse 260, CH-8057 Zurich, Switzerland; Institute of Parasitology, Vetsuisse-Faculty, University of Zurich, Winterthurerstrasse 266a, CH-8057 Zurich, Switzerland. Electronic address: walter.basso@vetsuisse.unibe.ch.

PMID: 31866312
DOI: 10.1016/j.ijpara.2019.11.002

Abstract

Toxoplasma gondii-infected pigs play a major role as a source of infection for humans and detection of high-risk herds is essential to implement control measures at the farm level. The aim of this study was to determine whether oral fluid (OF) could be used as a matrix to detect antibodies against T. gondii in infected pigs by immunoblot (IB). For this, OF from experimentally inoculated sows (n = 8) (serial samples) and naturally exposed group-housed fatteners (n = 42 groups, one sample/group) were analysed for IgG and IgA against T. gondii-SAG1 antigen by IB. Simultaneously, each animal was serologically tested for anti-T. gondii IgG by ELISA. Specific IgG was detected in the sera of all inoculated sows from 2 to 3 weeks post inoculation (pi) and in 3.4 to 92% of the pigs in 13 out of 42 groups. Experimentally inoculated sows showed positive OF-IB results for IgA (100%) and IgG (87.5%) at 1.5 weeks pi and continued yielding positive results for IgA (87.5-75%) and IgG (50%) until 4 weeks pi; however, from 8 weeks pi the frequency of detection of both isotypes was lower, despite constantly positive IgG values in serum-ELISA. Interestingly, consecutive daily samplings for 4 days at 13 and 30 weeks pi showed inconsistent results for some sows, showing that the antibody concentration in OF is prone to timely variations. Pooled OF from groups with 91 and 92% of seropositive pigs yielded positive IB results for IgG and IgA. Fattener groups with ≤13% of seropositive pigs gave negative IB results to both isotypes. Our results showed that antibodies to T. gondii can be detected in OF from infected pigs, and that IgA seems to be a more adequate target than IgG. Although OF does not seem to be a robust matrix to assess the serological status for T. gondii in individual animals, this diagnostic approach represents an interesting non-invasive, low-cost and animal welfare friendly option as a screening method at the farm level to determine high exposure to T. gondii in the herd.

Keywords: Cotton rope; IgA; IgG; Saliva; Swine; Toxoplasmosis.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Antibodies, Protozoan
Blotting, Western / veterinary
Immunoglobulin A / analysis
Immunoglobulin A / blood
Immunoglobulin G / blood
Immunoglobulin G / immunology
Immunologic Tests / methods
Immunologic Tests / veterinary*
Saliva / immunology
Swine Diseases / diagnosis
Swine* / immunology
Swine* / parasitology
Toxoplasma / immunology*
Toxoplasmosis, Animal / diagnosis*

Substances

Antibodies, Protozoan
Immunoglobulin A
Immunoglobulin G