Leptospiral attachment to extracellular matrix of mouse fibroblast (L929) cells

The attachment of leptospires to the extracellular matrix (ECM) remaining after mouse fibroblast (L929) cells on coverslips had been solubilized with Triton X-100 was examined. Each highly virulent line of Leptospira interrogans serovar copenhageni, canicola and pomona attached to ECM more effectively than intermediately virulent and avirulent lines of the same strains, suggesting a correlation between virulence and attachment to ECM. Inhibition of the attachment of highly virulent copenhageni to ECM was found in the presence of the homologous immunoglobulin G Fab fragment.     

Determination of blood volume in dogs using an enriched stable isotope 50Cr

For the measurement of canine blood volume, various experimental conditions and techniques have been investigated using a non radioactive stable isotope 50Cr. On the basis of the results in this preliminary work, erythrocytes were labeled using 50Cr. Five micrograms of 50Cr per 1 ml of blood was added and incubated for 60 min. The canine erythrocytes were tagged using 50Cr and injected into vein of the same dogs. The blood samples collected at 60 min after the injection were irradiated by thermal neutron for 20 min at the reactor of the JAERI. Activities of 51Cr (the 50Cr concentration method) and 51Cr/59Fe radioactivity ratios (the 51Cr/59Fe ratio method) in the samples were measured. There was a very high correlation (r = 0.97, P less than 0.001) between the blood volumes calculated by the 50Cr concentration method and the 51Cr/59Fe ratio method. The latter method is less complicated than the former, because measurement of the sample weight and correction of thermal neutron flux are unnecessary. The mean blood volumes calculated by the ratio method and the Evans blue method were 89.8 +/- 6.8 ml/kg B.W. (mean +/- SD) and 98.9 +/- 10.6 ml/kg, respectively, showing a significant difference between them (P less than 0.05). However, these values are almost in accord by correction of venous blood PCV values with factor 0.97. As a detection limit of 50Cr was approximately 0.1 ng per 1 ml of blood in this system, this method has been concluded to be applicable to the measurement of the blood volume of cattle.     

Physico-chemical properties of calf-diarrhea coronavirus

Replication of calf diarrhea coronavirus was not inhibited by 5-iodo-2′-deoxyuridine, indicating that the virus is an RNA virus. Sensitivity to ether and chloroform indicated that the virus is enveloped, and this was confirmed by electron microscopic observation of the virion. The virus was readily inactivated by trypsin and sodium deoxycholate. The virus was labile at 50°C in diluted medium, but readily stabilized in the presence of MgCl₂. It was stable at pH 5 and 7, while a slight loss of infectivity was observed at pH 3. The virus was readily filtered through membrane filters of 200 and 100-nm pore sizes, but not through 50-nm filters. The buoyant density of the virion in CsCl was estimated to be 1.25 g/ml.     

Genetic and phylogenetic analysis of glycoprotein of rabies virus isolated from several species in Brazil

Genetic and phylogenetic analyses of the region containing the glycoprotein (G) gene, which is related to pathogenicity and antigenicity, and the G-L intergenic region were carried out in 14 Brazilian rabies virus isolates. The isolates were classified as dog-related rabies virus (DRRV) or vampire bat-related rabies virus (VRRV), by nucleoprotein (N) analysis. The nucleotide and amino acid (AA) homologies of the area containing the G protein gene and G-L intergenic region were generally lower than those of the ectodomain. In both regions, nucleotide and deduced AA homologies were lower among VRRVs than among DRRVs. There were AA differences between DRRV and VRRV at 3 antigenic sites and epitopes (IIa, WB+ and III), suggesting that DRRV and VRRV can be distinguished by differences of antigenicity. In a comparison of phylogenetic trees between the ectodomain and the area containing the G protein gene and G-L intergenic region, the branching patterns of the chiropteran and carnivoran rabies virus groups differed, whereas there were clear similarities in patterns within the DRRV and VRRV groups. Additionally, the VRRV isolates were more closely related to chiropteran strains isolated from Latin America than to Brazilian DRRV. These results indicate that Brazilian rabies virus isolates can be classified as DRRV or VRRV by analysis of the G gene and the G-L intergenic region, as well as by N gene analysis.     

Localization of endothelin receptor subtype-A in the testis of rats, dogs, and monkeys

In order to evaluate the physiological roles of the testicular endothelin (Edn) signaling via Edn receptor subtype-A (Ednra) in mammals, the localization of Ednra was investigated by in situ hybridization and immunohistochemistry in the testis of rats, dogs, and monkeys. For in situ hybridization, a rat Ednra RNA probe which is highly homologous to the subcloned canine and monkey Ednra (88.7% and 87.9% identical, respectively) was used. Both Ednra mRNA and protein were detected in interstitial cells and cells in the basal compartment of the seminiferous tubules, mainly Sertoli cells, as well as spermatogonia and some early spermatocytes, but not spermatids. The localization pattern of Ednra was exhibited in a same manner among species, indicating that the physiological role of Edn signaling throughout Ednra was maintained in the mammalian testis.