A subset of Cowdria ruminantium genes important for immune recognition andprotection

Cowdria ruminantium causes the tick-borne rickettsial disease of heartwater , which is devastating to livestock production in sub-Saharan Africa. Curre nt diagnosis and control methods are inadequate. We have identified and seq uenced a subset of genes encoding recombinant antigens recognized by antibo dy and peripheral blood mononuclear cells from immune ruminants. The identi fied genes include many with significant similarity to those of Rickettsia prowazekii, genes predicted to encode different outer membrane proteins and lipoproteins and a gene containing an unusual tandem repeat structure. Evi dence is presented for immune protection by recombinant antigens in a mouse model of C. ruminantium infection. These data identify new recombinant ant igens for evaluation in vaccines and diagnostic tests to control heartwater . (C) 2001 Elsevier Science B.V. All rights reserved.