MOLECULAR CHARACTERIZATION OF PASTEURELLA-TESTUDINIS ISOLATED FROM DESERT TORTOISES (GOPHERUS-AGASSIZII) WITH AND WITHOUT UPPER RESPIRATORY-TRACT DISEASE

Isolates of Pasteurella testudinis recovered from clinically healthy d esert tortoises (Gopherus agassizii) and tortoises with upper respirat ory tract disease (URTD) were characterized in an attempt to identify strains associated with disease. Eighty-nine isolates, 52 from ill and 37 from healthy tortoises collected from Nevada (USA),June 1990 to Se ptember 1991, were genomically fingerprinted and grouped based on ribo type similarity. Twelve isolates (six from ill and six from healthy to rtoises) were further characterized with regard to whole-cell protein (WCP) and outer membrane protein (OMP) composition and their ability t o survive in normal tortoise plasma. The 89 isolates were initially di stributed into 33 distinct ribotype groups using the restriction enzym e EcoRI; five ribotypes contained over 50% of the isolates. Only one E coRI ribotype was comprised of multiple isolates (n = 4) exclusively r ecovered from tortoises with URTD. When the ten EcoRI ribotypes that c ontained more than one isolate per ribotype were further studied using a second restriction enzyme, EcoRV, one EcoRI/EcoRV ribotype containe d five isolates recovered from URTD tortoises and none from healthy an imals. The EcoRI ribotype comprised of four isolates, all from tortois es with URTD, was further separated into three distinct groups with Ec oRV. All 12 isolates studied grew equally well in normal tortoise plas ma, and when broth-grown WCP and OMP profiles were evaluated, no prote ins were unique to isolates from URTD tortoises. Iron-regulated OMP's were produced in three isolates examined, but these OMP's apparently w ere not virulence-related.