Suspensory ligaments (SL) from 32 Thoroughbreds and 32 Standardbreds were collected to evaluate the variation in muscle content with respect to age, breed, sex, limb, and use. Six transverse sections, each 3 to 5 mm thick, were obtained from each SL. Four sections were taken from the body of the SL and 1 from the midportion of each branch. Sections were stained with van Gieson picric acid-fuchsin solution, then photographed, and black-and-white slides were made from the processed negatives. The transverse-sectional area of the SL and the contained muscle were determined by use of a computer with a color monitor and a digitizing device with its associated software. The percentage of muscle was then calculated for each section, for the entire ligament, and for each horse. Results were analyzed by multiple-regression analysis and Duncan multiple-range test, using the General Linear Model of SAS. Standardbreds had 40% more muscle in their SL than did Thoroughbreds. There was no significant difference in the percentage of SL muscle among sex, age, use, individual limb, or forelimb vs hind limb. For Standardbred horses, females had significantly greater muscle area content than intact males. Also, hind limb muscle area content was significantly greater than forelimb muscle content. Thoroughbred horses between 2 and 10 years of age not in training had significantly more muscle content than horses of the same age not in training. The reasons for these differences remain unclear.

Pili from 11 distinct serotypes of Bacteroides nodosus were examined for diversity of pilin polypeptide subunits among serotypes and for purity of the pilin preparations. The pilin of all 11 samples was shown to be homogeneous. Mean +/- SD molecular weight of the pilin of 7 serotypes (A198, IV, V, VI, IX, XVII, and XVIII) was 18,500 +/- 100. The pilin of serotypes I, III, and VIII had molecular weight of 17,600, 19,400, and 19,000, respectively. Serotype XV differed greatly from the other 10 serotypes in that 2 distinct polypeptide bands with molecular weight of approximately 7,800 and 6,200 were detected. We suggest that these 2 low molecular weight bands resulted from proteolytic cleavage of the pilin protein.

Thirty-seven local isolates of Actinobacillus suis-like organisms from diseased and clinically normal horses and 1 Ilama were compared with reference strains of A suis, A lignieresii, A equuli, A capsulatus, A hominis, A (Pasteurella) ureae, and equine A suis-like organisms (ASLO) previously described in literature. Comparison was by cultural characteristics, carbohydrate fermentation, enzyme profiles, and whole-cell protein polyacrylamide gel electrophoresis. Carbohydrate fermentation, determined by API-CH gallery, divided 36 equine ASLO isolates into 6 API-CH biotypes. The Ilama isolate was an additional distinct biotype. The biochemical comparisons between A suis and ASLO did not reveal remarkable and consistent differences. Enzyme analysis revealed 5 API-ZYM biotypes, one of which included the same strains as one of the API-CH biotypes and consisted in both instances of 4 esculin-negative ASLO cultures and the reference strain of A lignieresii. We conclude that the 4 strains were hemolytic variants of A lignieresii. Protein electrophoresis disclosed 15 banding patterns, 10 of which represented equine ASLO strains. The reference strains of A suis shared the pattern predominant among equine ASLO. Four of the remaining reference strains of Actinobacillus species each had a unique profile, whereas the type strain of A capsulatus and the Ilama isolate had similar profiles. The groupings of cultures resulting from the different testing methods had little relation to each other and to the anatomic source of the strains except the strains comprising API-CH biotype III, which originated in the equine respiratory tract, and the A lignieressi cluster.

A recombinant cDNA probe from genome segment 5 obtained from a virulent US bluetongue virus strain (BTV-11 strain UC8) was hybridized to US and Israeli BTV prototypes and field isolates. The cloned genetic probe hybridized with US BTV prototype 10, but not with US prototypes 2, 11, 13, and 17; with the avirulent BTV-11 strain UC2; and with the Israeli prototype 10. When the probe was hybridized to field isolates from the US serotypes, it hybridized to 12 of 14 BTV-10 isolates and 4 of 17 BTV-11 samples, but not to the BTV-13 and BTV-17 samples tested. Hybridization was not observed with the Israeli field isolates studied. Results indicate that a reassortant event occurred between a strain of US BTV-10 and US BTV-11 that originated the BTV-11 strain UC8.

On the basis of serologic test results and isolation of leptospires from mature cattle, distribution and prevalence of Leptospira interrogans serovars and genotypes were compared by state and region of the United States. Relationships between isolation rate and month of sample collection, mean regional temperature, and mean regional precipitation were examined. Isolation rate and seroprevalence were significantly (P < 0.001) higher for southeastern, south central, and Pacific coastal regions than for other regions of the United States. Isolates of genotypes hardjo-bovis A and kennewicki A and B, and of serovar grippotyphosa appeared to be randomly distributed. Genotype hardjo-bovis B isolates came from a southern area of the country that extends from Georgia to New Mexico. To the authors' knowledge, this is the first recorded isolation of serovar hardjo from Hawaii. Although significant relationship was not documented between isolation rate and month or season of the year, seroprevalence for summer, fall, and winter was significantly (P < 0.001) higher than that for spring. Regional isolation rate was related more to mean temperature (r = 0.83; P < 0.05) than to mean precipitation amount (r = 0.34; P > 0.50).

Phenotypic characteristics of 12 paired, Salmonella serotypes isolated from healthy and ill chickens were compared. Variables compared included antibiotic resistance profiles, production of colicins and siderophores, mannose-sensitive hemagglutination of erythrocytes, resistance to serum complement, carbon source utilization, presence and transmissibility of R plasmids, and invasiveness in primary chicken kidney cell culture. Differences were found between pairs for utilization of carbon sources, mannose-sensitive hemagglutination of erythrocytes, and invasiveness in cell culture.

In vitro adherence to intestinal epithelial cells by enterotoxigenic Escherichia coli strains bearing K88, K99, F41, or 987P adhesins and of their variants not bearing adhesins (K88-, K99-, or F41-) was investigated in European Large White and Chinese Meishan pigs. Possible relationship between adherence and virulence was also examined. The K88-positive (K88+) strain strongly adhered to intestinal epithelial cells from 26 of 28 Large White pigs. This strain had previously been found to be highly virulent for Large White pigs. The only surviving pig was of nonadherent phenotype, and cells from 4 dehydrated moribund pigs had strong adherence. By contrast, the same K88+ strain found previously to have little pathogenicity for Meishan pigs adhered with variable intensity to cells from 17 of 23 Meishan pigs; correlation was not evident between adherence and virulence. The K99+F41+ strain of porcine origin and the F41+ strain generally adhered strongly to cells from 24 and 23 Meishan pigs, respectively, and to cells from 25 of 26 Large White pigs. Correlation was not found between adherence and virulence for the 2 strains. A K99+F41+ strain of bovine origin adhered to cells from 20 of 22 Meishan and 22 of 23 Large White pigs, and a K99-F41+ variant adhered to cells from 19 of 23 Meishan and 23 of 24 Large White pigs. The adhesin-negative variants never adhered to intestinal epithelial cells. Strain 987 known not to readily produce 987P adhesin after in vitro growth never adhered to cells during the test. Results indicated that K88, K99, and F41 adhesins were responsible for in vitro adherence and, except for the K88+ strain in Large White pigs, adherent phenotype was not a sufficient condition to make a pig susceptible to enterotoxigenic E coli. The contribution of physiologic factors and their genetic origin to the degree of resistance of the individual is not yet completely understood for every enterotoxigenic E coli strain and breed of pig.

We determined that the protein profiles of 14 isolates from animals with hemorrhagic septicemia were relatively homogeneous and could be placed in 2 distinct groups on the basis of their country of origin. Such differences correlated with the serotypic properties of the individual isolates; hemorrhagic septicemia isolates of Asian and North American origin (Carter B) had a major protein band with an apparent molecular mass of 32 kDa, whereas those of African origins (Carter E) had a major protein band with an apparent molecular mass of 37 kDa. The possession of a major 32-kDa protein band appeared to be unique to Carter B isolates, suggesting that electrophoresis may be a useful nonserologic technique for the identification of organisms of this serotype. Other major bands with apparent molecular masses of 27, 45, and 47 kDa were shared by all strains, regardless of their serotype. The lipopolysaccharides were of low molecular mass and relatively uniform from 1 isolate to the next.

An experiment was conducted to determine whether a persistent Salmonella newport infection could be established in swine, to determine duration of shedding and distribution of the organism in internal organs, and to determine whether changes occurred in antimicrobial susceptibility or plasmid profile of the organism during the course of long-term infection. Naturally farrowedSalmonella-free pigs (n = 22) were orally exposed to a multiply antimicrobial-resistant zoonotic strain of S newport when they were 7 weeks old. Tonsillar and rectal swab specimens were examined bacteriologically for S newport during the first week after exposure, then weekly for 7 weeks. Fecal samples were likewise examined weekly or every 2 weeks for 28 weeks after exposure. Necropsies of 2 or 3 randomly selected pigs were conducted at 2, 4, 8, 12, 16, 20, 24, and 28 weeks after exposure. A total of 45 specimens/pig representing the following internal organs or tissues were examined bacteriologically for S newport: liver, spleen, kidney, gallbladder, heart, heart blood, lung, stomach, and tonsils; segments of the intestinal tract with corresponding lymph nodes; and lymph nodes from lymphocenters of the head and neck, thoracic cavity, thoracic limbs, abdominal viscera, and abdominal wall. Exposure to S newport induced a mild and transient clinical response. The organism was recovered from 97% of tonsillar swab specimens and 89% of rectal swab specimens collected during 7 weeks after exposure and from 98% of fecal samples collected during 28 weeks after exposure. At necropsy, S newport was recovered most frequently from tonsils (86.4%), followed by segments of the intestinal tract from ileum to rectum (81.8% recovery from cecal contents), and from mandibular (68.2%), jejunal (50%), and ileocolic (45.5%) lymph nodes. Sporadic recoveries of the organism were made from other lymph nodes and from gallbladder, stomach, kidney, spleen, liver, and heart, varying from 2 to 20 weeks after exposure. The cranial portion of jejunum, medial iliac lymph nodes, dorsal superficial cervical lymph node, and heart blood of all pigs were culture-negative. Of 26 representative isolates of S newport recovered from body organs or feces during 28 weeks after exposure, 4 (15.4%) underwent changes in antimicrobial susceptibility pattern. Changes in plasmid profile of the organism were not detected during longterm infection of swine.

Proteins in sporulated and unsporulated oocysts of Eimeria maxima were characterized, using monoclonal antibodies (MAB), ELISA, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and protein (western) immunoblotting techniques. Three MAB (EM1, EM2, and EM4) were produced against proteins of sporulated oocysts. The ELISA results indicated that EM1 was reactive with sporulated oocyst proteins, EM2 was reactive with sporulated and unsporulated oocyst proteins, and EM4 was reactive with unsporulated oocysts and proteins. Separation of proteins in E maxima sporulated and unsporulated oocysts by SDS-PAGE indicated that sporulated oocysts had proteins of approximately 200 kilodaltons (kD) and distinct protein bands at 21.5 and 45 kD. Using SDS-PAGE, unsporulated oocysts had less-distinct high molecular weight protein bands (> 200 kD), compared with sporulated oocysts, and a distinct protein band at 31 kD. Use of all 3 MAB yielded negative results in western blot analysis of fractions obtained by SDS-PAGE.