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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Animal Parasitic Diseases Laboratory » Research » Research Project #436120

Research Project: Molecular Mechanisms Regulating Ostertagia ostertagi Infection in Cattle

Location: Animal Parasitic Diseases Laboratory

Project Number: 8042-32000-105-009-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: May 15, 2019
End Date: May 14, 2024

Ostertagia ostertagi is a gastrointestinal parasitic nematode (GI) that imposes a large economic impact on the US cattle industry. With increase in drug resistance, vaccination remains a viable alternative for control because it is environmental friendly and is effective against both susceptible and resistant populations. Understanding host-parasite interactions is critical for controlling parasite transmission. The goal of this research is to identify immunomodulatory effects of O. ostertagi on the host, predicated upon the following 3 objectives. Objective 1: To determine time-course expression of the immune mediated genes of cattle infected with O. ostertagi; Objective 2: To investigate O. ostertagi excretory secretory (ES) molecules that target the host innate immune cells, macrophages; and, Objective 3: To validate stage specific expression, characterization, vaccine efficacy of O. ostertagi secretory proteins responsible for host evasion.

The study will incorporate molecular, cellular and biochemical techniques. Objective 1: Time-course expression of the immune mediated genes. Blood will be collected at various time points, followed by total RNA isolation and processing for sequencing using the lumina Hiseq 2500. Sequencing data will be mapped independently to the bovine genome and gene expression levels of immune-related genes will be identified using state-of-the-art Next generation sequencing programs. Objective 2: Identifying the role of O. ostertagi (Oos) Excretory-Secretory (ES) molecules on host cells. ES molecules will be incubated with host cells, followed by identification of key host innate immune markers by PCR, by phenotypic analysis via confocal microscopy. and by LC-MS Mass Spectrophotometry. Protein-protein interactions will be assessed by proteomic software. Objective 3: Characterize vaccine efficacy of Oos ES proteins responsible for host evasion. Stage specific expression and characterization of Oos genes will be done by in silico identification of immune mediated genes from databases, verification by qPCR and then cloning and expression in bacterial expression system. Functional analyses will be done by substrate hydrolysis assays. Vaccine efficacy will be tested by immunizing animals with the recombinant products followed by challenge with Oos infective larvae. Daily fecal egg counts, weekly weight gains and total worm burdens will be assessed. Blood will be collected and Immune cells from the abomasum and antibody responses will be determined.