Epitheliocystis has been associated with heavy mortality and reduced growth of survivors in farmed Atlantic salmon (Salmo salar) (22). Ultrastructural studies of the epitheliocystis agent found in Atlantic salmon have revealed it to be an intracellular gram-negative coccoid bacterium with distinct developmental stages typical of bacteria of the order Chlamydiales (22). Epitheliocystis has been described in other salmonid hosts, e.g., juvenile steelhead trout (Oncorhynchus mykiss) (28) and cultured lake trout (Salvelinus namaycush) (3), as well as in a number of nonsalmonid species, including bluegill (Lepomis macrochirus) (16), striped bass (Morone saxatilis) (32), white perch (Morone americanus) (32), sea bream (Sparus aurata) (25), grey mullet (Liza ramada) (25), and cultured white sturgeon (Acipenser transmontanus) (14). Morphological studies of epitheliocystis agents in sea bream (S. aurata) have provided evidence for two distinct chlamydia-like developmental cycles associated with proliferative and nonproliferative host reactions (5). Although transmission electron microscopic examinations of intracellular inclusions have demonstrated that the agents of epitheliocystis in both salmonid and nonsalmonid hosts are gram-negative bacteria with developmental stages typical of members of the order Chlamydiales (5,14,22,28,32), the genetic relatedness of these bacteria has yet to be determined.Sequence data from the rRNA operon have revised phylogenetic relationships between Chlamydia species and chlamydia-like bacteria (CLB) (7,8,9). Reclassifying chlamydial species on the basis of 16S rRNA gene sequence identity, 16S and 23S ribosomal DNA (rDNA) sequences, and phenotypic characterization is considered by some to be the best means of taxonomically categorizing chlamydiae (24). Based on this approach, species within the family Chlamydiaceae have 16S rRNA gene sequences that are Ͼ90% identical (26), whereas chlamydia-like bacteria, defined as obligate intracellular bacteria having reticulate (RBs) and elementary bodies (EBs) characteristic of chlamydia, have been shown to have Ͼ80% 16S rRNA

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Equine coronavirus (ECoV) is a Betacoronavirus recently associated clinically and epidemiologically with emerging outbreaks of pyrogenic, enteric, and/or neurologic disease in horses in the United States, Japan, and Europe. We describe the pathologic, immunohistochemical, ultrastructural, and molecular findings in 2 horses and 1 donkey that succumbed to natural infection with ECoV. One horse and the donkey (case Nos. 1, 3) had severe diffuse necrotizing enteritis with marked villous attenuation, epithelial cell necrosis at the tips of the villi, neutrophilic and fibrinous extravasation into the small intestinal lumen (pseudomembrane formation), as well as crypt necrosis, microthrombosis, and hemorrhage. The other horse (case No. 2) had hyperammonemic encephalopathy with Alzheimer type II astrocytosis throughout the cerebral cortex. ECoV was detected by quantitative polymerase chain reaction in small intestinal tissue, contents, and/or feces, and coronavirus antigen was detected by immunohistochemistry in the small intestine in all cases. Coronavirus-like particles characterized by spherical, moderately electron lucent, enveloped virions with distinct peplomer-like structures projecting from the surface were detected by negatively stained transmission electron microscopy in small intestine in case No. 1, and transmission electron microscopy of fixed small intestinal tissue from the same case revealed similar 85- to 100-nm intracytoplasmic particles located in vacuoles and free in the cytoplasm of unidentified (presumably epithelial) cells. Sequence comparison showed 97.9% to 99.0% sequence identity with the ECoV-NC99 and Tokachi09 strains. All together, these results indicate that ECoV is associated with necrotizing enteritis and hyperammonemic encephalopathy in equids.

The natural aging process results in the physiological decline of multiple tissues and organ systems. Changes commonly occur with middle age and include decreased skeletal muscle mass, bone mineral density, cardiac output, and insulin sensitivity, and increased adiposity, all of which can contribute to the onset of sarcopenia, osteoporosis, heart failure, or type 2 diabetes. Recent studies suggest that myostatin may influence many of these systems. We therefore sought to determine whether they are affected by aging, especially in 'middle-aged' Mstn K/K mice (12-20 months old (m.o.)). Although body weights were similar in wild-type (WT) and Mstn K/K mice, lean fat-free mass and skeletal muscles composed of predominantly type I, II, and mixed fibers were significantly heavier in Mstn K/K mice. These differences were accompanied by lower total adiposity, especially in female mice, white and brown fat pad weights, and adipocyte size. Hearts were heavier in Mstn K/K mice across a large age range (3-24 m.o.) and exhibited signs of dilated cardiomyopathy at rest, which include lower strain measurements compared with WT myocardium. However, Mstn K/K mice responded better to isoproterenol stress tests with greater increases in fractional shortening and ejection fraction-differences that were again more apparent in females and which are consistent with physiological cardiac hypertrophy. Spleens and kidneys were also smaller, although histologically normal, in Mstn K/K mice. These data together suggest that attenuating myostatin could potentially prevent or possibly treat pathological conditions that develop with age. Additional studies are nevertheless needed to definitively assess potential risks to cardiac function.

CSF samples collected at veterinary clinics remote from a diagnostic laboratory or during nonoperational hours may be preserved through the addition of autologous serum. Evaluation of such samples is likely to result in an accurate diagnosis for at least 48 hours after collection.