Effect of Neospora caninum infection on central nervous system immune response in Bos taurus and Bos indicus

• Grant number: 06/00197-5
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: July 01, 2006
• End date: June 30, 2009
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Solange Maria Gennari
• Grantee: Luciana Mori Viero
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Neospora caninum infection is an important cause of abortion and natimortality in bovine cattle in several countries worldwide. Since its first description on 1988, advances on biological and epidemiological characterization has been done but there is no known effective control and treatment to date.Under experimental conditions, activation of specific protective mechanisms of the immune system can decrease abortion losses and parasite vertical transmission. However efficacy of vaccination programs under field conditions is still lower than expected. Host response individual variation, effect of gestation on immune system activity and parasite pathogenicity variation are the possible explanations to the transmission persistence.Differences between Bos taurus and Bos indicus resistance to ectoparasites and intestinal helminths are well documented, but there is no information about variation against N. caninum infection. It is known that ectoparasites and helminths induce Th2 type response and neosporosis is controlled by Th1 IFN-g mediated cellular immune response.Neospora caninum is known to have a affinity to Central Nervous System (CNS). Main symptoms are observed in young animals and are basically ataxia and hind limbs hyperextension with high mortality rates. Laboratory findings include microgliosis with or without necroses localized lesions mainly in cerebral cortex, encephalitis with necrosis and CNS non supurative inflammation.Using IFN-g as a reference cytokine to study resistance to infection, the objective of the present project is to 1) quantitate immune related (IFN-g, TNF-a, iNOS, IL-4, IL-10, TGF-b) gene expression using Real-Time PCR in CNS tissues and 2) to identify immune cell populations (CD4+ and CD8+ T cells and macrophages) by immunohistochemistry technique and that way, to investigate possible differences between Bos taurus and Bos indicus local immune responses against acute N. caninum infection.