A POLYGEN(TM)-adjuvanted killed Neospora caninum tachyzoite preparation failed to prevent foetal infection in pregnant cattle following i.v./i.m. experimental tachyzoite challenge

A. G. Andrianarivo, Joan D Rowe, B. C. Barr, Mark L Anderson, A. E. Packham, K. W. Sverlow, L. Choromanski, C. Loui, A. Grace, Patricia A Conrad

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71 Scopus citations


Cattle immunised with a POLYGEN(TM)-adjuvanted killed Neospora caninum tachyzoite preparation were previously shown to produce interferon (IFN)-γ at levels similar to those of tachyzoite-infected cattle. In view of the critical role of IFN-γ in resistance of mice to N. caninum infection, these results prompted us to test the POLYGEN(TM)-adjuvanted preparation in pregnant cattle to determine whether it will be able to prevent foetal infection following an experimental tachyzoite challenge. Seven heifers were immunised at 35 and 63 days of gestation with the POLYGEN(TM)-adjuvanted preparation, while five heifers were inoculated with POLYGEN alone at the same days of gestation. Four weeks later, all heifers were challenged with a combined i.v./i.m. inoculation of tachyzoites. The same challenge was given to seven unimmunised heifers at the same stage of gestation. An additional unimmunised heifer was inoculated with uninfected monolayer cell culture material. All challenged heifers, immunised and unimmunised, had infected foetuses. Immunised heifers developed both parasite-specific humoral and cellular immune responses, characterised by increased IFAT titres, a predominant IgG1 response, elevated lymphoproliferative response and IFN-γ production. Following tachyzoite challenge, they developed an anamnestic humoral response and produced similar amounts of IgG1 and IgG2 antibodies, but did not have an anamnestic cellular immune response. The lack of anamnestic cellular immune response and/or the large i.v/i.m tachyzoite inoculum may have contributed to the failure of the preparation. Copyright (C) 2000 Australian Society for Parasitology Inc.

Original languageEnglish (US)
Pages (from-to)985-990
Number of pages6
JournalInternational Journal for Parasitology
Issue number9
StatePublished - Aug 2000



  • Bovine neosporosis
  • Foetal infection
  • Intramuscular experimental challenge
  • Intravenous experimental challenge
  • Killed tachyzoite preparation
  • Neospora caninum
  • POLYGEN(TM) adjuvant

ASJC Scopus subject areas

  • Parasitology
  • Infectious Diseases

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