Abstract
Borna disease virus (BDV) causes nonsuppurative encephalomyelitis in a variety of vertebrates (horses, cattle, sheep, goats, rabbits, cats, and dogs). The disease is endemic in restricted areas of central Europe. Many infected animals are asymptomatic. In sheep, once overt disease has developed, the prognosis for recovery is poor. Little is known about the epidemiology of Borna disease. Investigators in Germany determined the prevalence of 1) BDV-specific antibodies by indirect immunofluorescence and 2) BDV RNA by RT-PCR in a closed herd of moorland sheep in southeast Germany over a three-year period. Their results showed that the virus could persist in asymptomatic animals and be shed in nasal and conjunctival fluids and in saliva for up to two years. Culling asymptomatic infected animals did not reduce the prevalence of BVD infection. Thus, eradication of the disease in endemic areas will be difficult.
Vahlenkamp TW, Konrath A, Weber M, Muller H: Persistence of Borna disease virus in naturally infected sheep. J Virol 76:9735–9743, 2002.
Mitochondria are complex cell organelles that produce energy by oxidative phosphorylation. Heritable disorders of mitochondrial function are associated with a variety of clinical syndromes, including multisystemic metabolic and neurodegenerative diseases. These diseases can be difficult to diagnose, because mitochondrial proteins are encoded both in the nucleus and in the mitochondrion, and mitochondrial DNA mutations may be present in only a subset of mitochondria. Recently, scientists have demonstrated that immunocytochemistry can be used for rapid and specific diagnosis of mitochondrial disease. Primary cultures of fibroblasts from patients were stained for porin (a control for mitochondrial mass) and for specific mitochondrial proteins (subunits of complexes I, II, III, IV, V and pyruvate dehydrogenase). This technique was rapid, sensitive, and reproducible. It identified the loss of specific mitochondrial molecules and readily distinguished between nuclear (homogeneous staining pattern) and mitochondrial (heterogeneous staining pattern) mutations.
Hanson BJ, Capaldi RA, Marusich MF, Sherwood AW: An immunocytochemical approach to detection of mitochondrial disorders. J Histochem Cytochem 50:1281–1288, 2002.
Epithelial lesions caused by human papillomaviruses (PV) can progress to cancer. Because PV are highly host-specific, most in vivo studies of PV pathogenesis use animal PV that cause disease in their animal hosts similar to human disease. A large group of collaborating scientists carried out an extensive study aimed at determining similarities among the life cycles and tissue tropisms of animal and human PV. Viruses examined included canine oral PV, rabbit oral PV, cottontail rabbit PV, bovine PV type I, and human PV types 1, 2, 11, and 16. They concluded that only rabbit oral PV has a tissue tropism and life cycle similar to human mucosal PV; it is thus suitable for studying human PV replication and for testing prophylactic vaccines. However, the rapid regression of lesions caused by rabbit oral PV makes it an unsatisfactory model in which to test therapeutic vaccines and antiviral agents. Cottontail rabbit PV, on the other hand, causes persistent nonproductive infections in nonmucosal epithelium and can be used to test treatments for established PV infection.
Peh WL, Middleton K, Christensen N, Nicholls P, Egawa K, Sotlar K, Brandsma J, Percival A, Lewis J, Liu WJ, Doorbar J: Life cycle heterogeneity in animals models of human papillomavirus-associated disease. J Virol 76:0401–10416, 2002
A retrospective study carried out in Colorado identified a distinct form of intraluminal enteric hemorrhage in cattle that was termed “hemorrhagic bowel syndrome” (HBS). HBS is characterized by the presence in the small intestine of large intraluminal blood clots that may cause obstruction. The prognosis for affected animals is grave, unless surgery is performed to remove the obstructing clot. Of 20 cattle with HBS examined for the study, 17 had Clostridium perfringens in their feces. Clostridium isolates from 10 cows were genotyped by multiplex polymerase chain reaction and all were Type A. This suggests that the bacterium may be responsible for HBS.
Dennison AC, VanMetre DC, Callan RJ, Dinsmore P, Mason GL, Ellis RP: Hemorrhagic bowel syndrome in dairy cattle: 22 cases (1997–2000). J Am Vet Med Assoc 221:686–689, 2002.
Using confocal and widefield microscopy, investigators have been able to image arterial thrombus formation in the mouse. Fluorescent antibodies against the platelet-specific antigen CD41, fibrin, and tissue factor were administered intravenously, then a laser was used to induce endothelial injury and thrombus formation in a cremaster muscle arteriole. Intravital microscopy was then used to image thrombus formation in real time. While fibrin and platelets were distributed throughout the thrombus, tissue factor was concentrated at the junction of the thrombus with the vessel wall. This technique will be valuable for elucidating the pathogenesis of thrombi and for testing anti-thrombotic therapies.
Falati S, Gross P, Merrill-Skoloff G, Furie BC, Furie Bruce: Real-time in vivo imaging of platelets, tissue factor and fibrin during arterial thrombus formation in the mouse. Nature Med 8:1175–1180, 2002.