COMPARATIVE IMMUNIZING POWER OF INFECTIONS, SALIVARY EXTRACTS, AND INTESTINAL EXTRACTS OF HYALOMMA-MARGINATUM MARGINATUM IN CATTLE

Tick concealed antigens have been successful in producing immunity tha t inhibits tick fertility, but require periodic revaccination and are little effective in preventing tick feeding, which is critical to stop pathogen transmission. Tick natural salivary antigens also induce imp ortant immunity, but revaccination may be unnecessary in enzootic area s. In addition these antigens may inhibit tick feeding. We immunized g roups of three tick-naive calves with four prior infestations with Hya lomma marginatum marginatum, a salivary extract (SE), or an intestinal extract (IE) of the ticks. The calves were challenged with 100 pairs of homologous ticks and characteristics representing tick feeding or f ertility were recorded and compared between groups. The percentage of attachment was inhibited by 46% by the infestation-generated immunity, 47% by the SE-generated immunity, and 0% by the IE-generated immunity . The percentage of engorgement was reduced 40% by the infestations, 5 7% by the SE, and 29% by the IE. The length of feeding was prolonged 9 2% by the infestations, shortened 44% by the SE, and not affected by t he IE. The weight of the engorged females was decreased 67% by the inf estations, 64% by the SE, and 31% by the IE. The percentage of engorge d ticks that oviposited was inhibited 52% by the infestations, 27% by the SE, and 63% by the IE. The preoviposition period was prolonged 160 % by the infestations, 80% by the SE, and 140% by the IE. The egg weig ht was reduced 60% by the infestations, 60% by the SE, and 66% by the IE. Taking into account mortality before oviposition, fertility was in hibited 88.2% by the infestations, 87.5% by SE, and 91.4% by the IE. T he effect of IE immunization on tick feeding was not significant stati stically.