Passive immunotherapy using specific anti-ES24 antibodies for the control of Haemonchus contortus in lambs.

• Grant number: 24/21238-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: April 01, 2025
• End date: March 31, 2029
• Field of knowledge: Agronomical Sciences - Veterinary Medicine
• Principal Investigator: Ana Carolina de Souza Chagas
• Grantee: Rafaela Tami Ikeda Kapritchkoff
• Host Institution: Embrapa Pecuária Sudeste. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA). Ministério da Agricultura, Pecuária e Abastecimento (Brasil). São Carlos , SP, Brazil
• Associated research grant: 24/09500-0 - Immunotherapy in lambs using specific antibodies against the recombinant 24kDa excretory-secretory protein of Haemonchus contortus., AP.R

Abstract

Haemonchus contortus, responsible for the haemonchosis disease, is the main gastrointestinal nematode (GIN) that infects sheep. Excretory-secretory (ES) products are relevant target antigens, as they are continuously secreted by parasites and have been associated with the development of immune protection against H. contortus. In a recent study, H. contortus IgM isotype antibodies against ES24 showed a moderate negative correlation with egg count per gram of feces (EPG) and a moderate positive correlation with packed cell volume (PCV) values in lambs infected with this GIN, indicating the importance of these antibodies in the host's immune-protective response to infection. Therefore, this project proposes to develop and evaluate the efficacy of a passive immunotherapy protocol through oral administration (on days D0 (approximately between 190 and 200 days of age), D7, D14, and D21) of anti-ES24 H. contortus antibodies in White Dorper lambs naturally infected with this GIN. To this purpose, specific antibodies against H. contortus ES24 protein will be produced in Santa Inês sheep. Blood samples will be collected from the lambs for a complete blood count, PCV measurement, and specific antibodies (IgM, IgG, and IgA) against H. contortus L3 and H. contortus ES24 by indirect ELISA, as well as oral/nasal and fecal swabs for EPG counts. On day 28, the animals will be euthanized, and the abomasal contents will be collected for parasite counts, and abomasal tissue samples will be submitted to histopathological analysis and gene expression quantification. The development of a new immunoprophylactic strategy may be applicable as an important tool for the control of H. contortus in lambs.