EPIZOOTIC BOVINE ABORTION IN A DAIRY-HERD - CHARACTERIZATION OF A CHLAMYDIA-PSITTACI ISOLATE AND ANTIBODY-RESPONSE

A chlamydial agent was recovered from the placental cotyledons of an a borting cow from a 100-cow dairy herd in Cumbria. Immunoblotting analy sis of purified elementary bodies of the isolate revealed a reactivity pattern typical of serotype I Chlamydia psittaci strains. Nucleotide sequencing of the major outer membrane protein (MOMP) gene further con firmed the isolate, BA1, as a serotype I strain. The sequence was iden tical to that of the type strain of ovine enzootic abortion, B577. In both the antigenic and MOMP sequencing analyses BA1 was distinguishabl e from serotype II C. pecorum strains. A sequential series of sera obt ained from the aborting cow, from which BA1 was recovered, was analyse d by immuno-blotting against the homologous isolate, and demonstrated reactivity to major chlamydial antigens over a 110-day period. Close c ontact between ruminant species on the farm suggested that the C. psit taci strain may have been transmitted to cattle from infected sheep.