Fixation of mutations in the viral genome during an outbreak of foot-and-mouth disease: heterogeneity and rate variations.

Rates of fixation of mutations during the evolution of the foot-and-mouth disease virus (FMDV) C1 in nature have been estimated by hybridization of viral RNA to cloned cDNAs representing defined FMDV genome segments, and comparison of the selected RNAs by T1 RNase oligonucleotide fingerprinting. Values ranged from less than 0.04 X 10(-2) to 4.

Biochemical characterization of a foot-and-mouth disease virus strain attenuated for cattle. Brief report.

Wild-type, virulent (A-24 Cruzeiro subtype) foot-and-mouth disease virus (FMDV), a related attenuated strain and revertants of the attenuated strain were examined by titration on primary bovine kidney (PBK) and baby hamster kidney (BHK-21) cells, as well as, by infection of unweaned mice. Wild type virus grew equally well in all three systems, whereas the attenuated strain had a titer 2-3 log lower in PBK cells than in the other 2 assays. Within 9 successive passages in BHK-21 cells the attenuated strain gave rise to revertants that had regained the growth properties of wild-type virus in PBK cells.

Homologous interference by a foot-and-mouth disease virus strain attenuated for cattle.

An attenuated strain of foot-and-mouth disease virus (FMDV) of the A24 Cruzeiro subtype grew less well than wild-type virus in primary bovine fetal kidney (PBK) cells resulting in a 4-log lowered efficiency of plaque formation. Both wild-type and attenuated virus grew equally well in baby hamster kidney (BHK) cells and in suckling mice. Using PBK cells, virus-specific RNA of the wild-type accumulated up to 6 hours after infection.

Detection of vesicular stomatitis virus RNA and its defective-interfering particles in individual mouse brains.

To develop a highly sensitive and direct assay for defective interfering (DI) particles of vesicular stomatitis virus (VSV), we reverse transcribed RNA from DI particles and cloned the DNA in pBR322 and used it as hybridization probes. At the lower limit, cDNA of about 850 nucleotides detected 150 pg of VSV RNA. For differentiation of hybridizable sequences found in the RNA of DI particles from complementary or identical sequences in the L mRNA or standard genomic RNA of VSV, RNA obtained from mouse brains was first separated by size, blotted onto nitrocellulose, and then hybridized to in vitro-labeled cDNA probe.

[Synthesis of 10S particles in cells infected with aphthovirus].

In the present study, evidence is presented for the existence of a morphogenetic intermediary that may be a precursor of the procapsids in the assembling process. BHK21 clone 13S cells were infected with Aphthovirus A24 (Cruzeiro strain), and pulse-chase experiments were carried out using 3H-leucine. Cytoplasmic extracts were then prepared at appropriate times, and analyzed by sucrose-gradient ultracentrifugation.

Morphogenesis of foot-and-mouth disease virus. I. Role of procapsids as virion Precursors.

The role of procapsids during foot-and-mouth disease virus multiplication was studied on infected BHK-21 cells. Purified virus and procapsids were obtained by treating the infected cytoplasmic extracts with RNase and EDTA. The synthesis of virus, procapsids, and total particles was determined in pulse-chase experiments.

[Intracranial pressure. Direct measurement in the cisterna magna].

The intracranial cisternal or supraoccipital punction in the sitting position, was undertaken in 523 cases, of which 329 presented increased intracranial pressure. The procedure must be done by experts, and was well tolerated. There were no cases of death, arterial hemorrhages or medullary lesions.

Inhibition of foot and mouth disease virus and procapsid synthesis by zinc ions. Brief report.

Zinc ions inhibit virus production and viral RNA synthesis in FMDV infected-BHK 21 cells. The degree of inhibition depends upon the zinc concentration and the time of addition of the drug. A differential inhibition on virus and procapsids synthesis was observed.

Intracranial circulatory insufficiency. Surgery of carotid atheroma.

Clinical and radiological studies are presented from 81 cases of intracranial circulatory insufficiency due to extracranial atherosclerosis, and the results of surgical treatment are given.

Continuous peroperative supraoccipital cisternal drainage.

1. The technique of continuous peroperative supraoccipital cisternal drainage for intracranial decompression by means of a slow and progressive removal of CSF from the ventricles and the basal cisterns is described. 2.

Encephalography using supra-occipital tapping of the cisterna magna.

A report is given of the results of supra-occipital tapping of the cisterna magna and dynamic encephalography by that route. In 72 patients with cranial hypertension this encephalography was well tolerated. Supra-occipital tapping is less dangerous than suboccipital puncture as regards the possibility of injury to the medulla.