Monoclonal antibodies to Toxoplasma gondii strain 119 identify recently isolated Danish strains as one group

Four mAb raised against the Danish Toxoplasma gondii strain 119, were selected by screening hybridoma supernatants by indirect immunofluorescence against tachyzoites of the RH strain in order to obtain strain-restricted markers. Strain restriction extended beyond discrimination of the 119 and RH strains, as demonstrated on a further six T. gondii reference strains [BK and GT1 (group A), NTE and 561 (group B), and NED and C56 (group C)]. The bradyzoite-specific mAb, 4.3, reacted to the GT1, NTE and 561 strains, but not to the BK, NED or C56 strains. The tachyzoite-specific mAb, 4.25, reacted to all strains tested except the RH strain, while mAb 5.1 reacted to tachyzoites of strains NTE and 561, but not to those of the BK, GT1, NED or C56 strains. Monoclonal antibody 5.15 reacted with the same strain restriction as monoclonal antibody 5.1, but to bradyzoites as well as tachyzoites. A T. gondii strain collection representative for a small geographic area (Denmark) was established within a short time span from a variety of animal species. Using the mAb as typing reagents to this Danish strain collection, all 36 animal and two human strains were identified as having the same reaction pattern as strains 119, NTE and 561.