IFN-γ As an Indicator of Successful Immunization of Goats Vaccinated with a Killed Cowdria ruminantium Vaccine

• Published in: Annals of the New York Academy of Sciences Vol. 969; no. 1; pp. 126 - 130
• Main Authors: ESTEVES, I., BENSAID, A., MARTINEZ, D., TOTTE, P.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2002
• Subjects: Animals; Bacterial Vaccines - immunology; Cattle; Cowdria ruminantium; Dose-Response Relationship, Immunologic; Ehrlichia ruminantium - immunology; Enzyme-Linked Immunosorbent Assay - methods; Enzyme-Linked Immunosorbent Assay - veterinary; gamma interferon; Goat Diseases - microbiology; Goat Diseases - prevention & control; Goats; Heartwater Disease - microbiology; Heartwater Disease - prevention & control; immunization; Interferon-gamma - biosynthesis; Interferon-gamma - blood; Kinetics; Random Allocation; vaccine; Vaccines, Inactivated - immunology
• ISSN: 0077-8923; 1749-6632
• DOI: 10.1111/j.1749-6632.2002.tb04363.x

: Cowdria ruminantium‐induced production of IFN‐γ was measured by ELISA on a weekly basis during the course of vaccination with killed organisms emulsified in ISA50. Upon challenge, all (3/3) vaccinated animals that gave the lowest IFN‐γ response died of peracute cowdriosis. On the other hand, only one of three animals showing high IFN‐γ responses to vaccination died, but with a delay of 4 days in comparison with naïve controls. Thus, there seems to be a threshold level of IFN‐γ below which the probability for vaccinated animals to survive a lethal challenge is very low. During challenge, a much lower, but still physiologically meaningful production of IFN‐γ was detected using the 24‐hour whole blood assay on day 5 after infection in animals controlling the infection. In contrast, IFN‐γ production was absent or negligible in naïve and vaccinated animals that died within 8‐10 days after infection. Although these results need to be validated on a larger number of animals, they strongly suggest that IFN‐γ is a useful indicator of protective immunity in animals immunized with killed Cowdria.