Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 12, 1997
Publication Date: N/A
Interpretive Summary: The nematode Ostertagia ostertagi is the predominant cause of parasite-induced production losses in cattle throughout temperate regions of the world. This predominance is partially due to the slow and incomplete development of protective immune responses. Although a primary O. ostertagi infection does not elicit protective immunity, such infections have a profound effect on the host immune system, including elevated levels of B-cells, gamma-delta T cells and cells expressing activation markers in both abomasal lymph node and mucosal cell populations. Cytokines are critical for the regulation of these immune responses. For this reason cytokine gene expression was investigated in mucosal (lamina propria) lymphocytes of cattle after a primary infection by O. ostertagi. Results indicated an overall increase in transcripts for the cytokines, interleukin-4 (IL-4) and interferon-gamma at both 10 and 60 days after infection, while changes in IL-10 mRNA expression were delayed till 60 days after infection. These results confirm that cytokine mRNA profiles induced by O. ostertagi infection in bovine shown a less restricted Th1/Th2 profile that than observed in nematode infection in murine models. These findings represent an important step in identifying the basis for delayed development of protective immunity against this parasite.
Technical Abstract: Changes in cell surface markers and cytokine transcription were analyzed in lamina propria lymphocytes from control animals (non- infected calves) and calves after a single very high, but non- protective primary infection with Ostertagia ostertagi. Flow cytometry of cells recovered from the lamina propria showed an increase in the percentages of IgM+, WC1+ and IL2R+ bearing cells 10 days after infection; however, 2 months after infection, cell staining was comparable to preinfection levels. Transcription levels of interleukin-2 (IL-2), IL-4, IL-10 and IFN-gamma mRNA were measured using a competitive reverse transcription-polymerase chain reaction. Results indicated elevated levels of IL4 and IFN-gamma in the infected animals at 10 days and at 60 days after infection. Transcription of IL-10 was also increased; however, this change was not observed until 60 days post-infection.