Neospora caninum in pigs and pig farmers in India: Examining the prevalence, immunodominant antigens and associated risk factors

• Published in: Microbial pathogenesis Vol. 200; p. 107352
• Main Authors: Mishra, Veena, Mitra, Pallabi, Shinde, Shilpshri, Chaudhari, Sandeep, Deshmukh, Abhijit S.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2025
• Subjects: Animals; antibodies; Antibodies, Protozoan - blood; Antigens, Protozoan - immunology; cattle; China; Coccidiosis - epidemiology; Coccidiosis - immunology; Coccidiosis - parasitology; Coccidiosis - veterinary; DNA; DNA, Protozoan - genetics; Enzyme-Linked Immunosorbent Assay; Farmers; genes; Genotyping; Humans; immune response; Immunodominant antigens; Immunodominant Epitopes - immunology; Immunoglobulin G - blood; India; India - epidemiology; Neospora - genetics; Neospora - immunology; Neospora - isolation & purification; Neospora caninum; parasites; pathogenesis; Pig farmers; Prevalence; Protozoa; Protozoan Proteins - immunology; reproductive efficiency; risk; Risk Factors; sequence analysis; Seroepidemiologic Studies; Serology; seroprevalence; Slaughtered pigs; Swine; Swine Diseases - epidemiology; Swine Diseases - immunology; Swine Diseases - parasitology; tachyzoites; India; China; Slaughtered pigs; Genotyping; Neospora caninum; Immunodominant antigens; Serology; Pig farmers; Risk factors
• ISSN: 0882-4010; 1096-1208; 1096-1208
• DOI: 10.1016/j.micpath.2025.107352

Neospora caninum, a protozoan parasite, is a major cause of reproductive failure in cattle and affects reproductive efficiency in pigs worldwide. Due to the limited data on N. caninum infection in pigs and humans in India, this study aims to investigate the prevalence of N. caninum in slaughtered pigs and among pig farmers, as well as to identify the factors that contribute to the infection. Additionally, we determined the major antigens that trigger antibody development in seropositive subjects. A total of 403 slaughtered pigs and 103 pig farmers were screened for N. caninum antibodies and parasite DNA. Thirty-five pigs (8.7 %) tested positive for antibodies, with titers ranging from 50 to 3200, as determined by NAT, ELISA, and IFAT; however, none of the pig farmers tested positive for N. caninum. All seropositive pigs had specific antibodies against N. caninum, which resulted in reduced invasion of host cells by the parasites and recognized multiple native and recombinant proteins (SAG1, GRA7, and MAG1) found in both the tachyzoite and bradyzoite stages. Also, seven pigs showed low IgG avidity, and 3 seropositive pigs tested positive for the NC-5 gene PCR, indicating a recently acquired infection in 0.7–1.7 % of the population. A comparison of NC5 sequence analysis of three positive samples revealed approximately 85 % similarity and was closely related to pig isolates from China. Additionally, we found older animals (>1 year), dogs and rodents in the farms, and outdoor access significantly contribute to N. caninum seropositivity in pigs. Overall, this study demonstrates the low occurrence of anti-N. caninum antibodies in pigs with a robust immune response against asexual stage antigens, highlighting their potential for diagnosis. •First report on Neospora caninum prevalence in pig and pig farmers in India.•8.7 % seroprevalence with 1.7 % active infection in pigs and no seropositivity in pig farmers.•Infection generates a strong antibody response against tachyzoite and bradyzoite antigens.•Positive sera reacts with key immunodominant proteins, SAG1, GRA7, and MAG1.