Variation in foot-and-mouth disease virus isolates in Kenya: an examination of field isolates by T1 oligonucleotide fingerprinting.

Ribonuclease T1 oligonucleotide maps of strains of 4 of the endemic serotypes of foot-and-mouth disease virus isolated in Kenya between 1964 and 1982 have been compared with data obtained in complement-fixation and neutralization tests. There was a continual change in the oligonucleotide maps obtained for all the serotypes examined. This genetic heterogeneity was generally associated with antigenic variation. Viruses isolated during the 12-month course of an epidemic of the SAT 1 serotype showed few changes in their oligonucleotide fingerprints, and were serologically related. These maps form a data base that will be useful in future epidemiological studies on the maintenance and spread of foot-and-mouth disease virus in this region.

Application of RNase T1 one- and two-dimensional analyses to the rapid identification of foot-and-mouth disease viruses.

The analysis of several isolates of foot-and-mouth disease virus by RNase T1 fingerprinting of the 32P-labeled RNA is described. It has been shown that use of the 35S induced RNA instead of the virus particle RNA has two advantages. (i) About 40 times more radioactivity is incorporated into the induced RNA. (ii) The RNA can be prepared much more rapidly, thus increasing the value of the technique in rapid diagnosis. One-dimensional maps, in which the RNase T1 oligonucleotides are separated according to size, have been shown to provide a valuable screening method for distinguishing between viruses. Those viruses giving similar one-dimensional maps also gave similar two-dimensional maps. The value of using the length of the polycytidylic acid tract of foot-and-mouth disease virus as a diagnostic tool is also discussed.

Molecular approach to the epidemiology of swine vesicular disease: correlation of variation in the virus structural polypeptides with serological properties.

Variation has been observed in the structural polypeptides of swine vesicular disease viruses isolated from the United Kingdom and Hong Kong. Despite the limited number of isolates examined, several distinct polypeptide patterns were obtained when the virus structural proteins were examined by polyacrylamide gel electrophoresis. Isolates from outbreaks in the United Kingdom which were known to be connected gave the same polypeptide pattern, whereas viruses with different polypeptide patterns could not be traced to a common source. The different polypeptide patterns were obtained consistently and were not altered by passage of the virus in tissue culture. In general, isolates with identical polypeptide patterns could not be distinguished by neutralization or antibody blocking tests or by competition radioimmunoassays. However, isolates with different polypeptide patterns could be differentiated by antibody blocking tests or radioimmunoassay. The correlation between the serological tests and the polyacrylamide gel electrophoresis analyses illustrates the value of analyzing structural polypeptides in the epidemiological study of swine vesicular disease.

Purification of poliovirus by affinity chromatography.

Poliovirus type 1 (Mahoney strain) has been purified by retention on a Sepharose 4B-antibody column and elution with 3M K thiocyanate. The virus was recovered in excellent yield and its purity was as high as that achieved by detergent treatment followed by sucrose gradient centrifugation. The column could be re-used and its capacity was sufficiently high to make it a useful method for the purification of milligram quantities of the virus.

Relationship of a virus from Tellina tenuis to infectious pancreatic necrosis virus.

The physicochemical and serological properties of a virus isolated from the bivalve mollusc, Tellina tenuis, have been examined. The virus has a diam. of 59 nm, sediments at 430S in sucrose gradients and bands at a density of I-32 g/ml in CsCl. The virus contains RNA with a mol. wt. about 2-8 X 10(6) as extimated by polyacrylamide gel electrophoresis but in sucrose gradients the RNA sediments at 14S. The virus RNA is resistant to ribonuclease under conditions in which ribosomal RNA and the single stranded Mengo virus RNA are completely hydrolysed. Two major polypeptides, mol. wt. 67 and 40 X 10(3), and minor polypeptide, mol. wt. 110 X 10(3), are present in the virus particle. These properties are similar to those found in different serotypes of infectious pancreatic necrosis (IPN) virus. Although there was only a very low level of cross-neutralization between Tellina virus and IPN virus. there was some cross-reaction in immune electron microscopy tests and in immunofluorescence tests with infected tissue culture cells. This cross reaction, together with the close similarity in morphology and physiochemical properties, suggests that Tellina virus and IPN virus belong to the same virus group.

Comparison of swine vesicular disease virus and Coxsackie B5 virus by serological and RNA hybridization methods.

The relatedness of swine vesicular disease virus (SVDV) and Coxsackie B5 virus has been studied by virus neutralization and immunodiffusion tests and by hybridization of the virus RNAs. Clearly defined differences between the two viruses were found by the three methods. Isolates of SVDV from several countries were very closely related but could be differentiated. Recent isolates of Coxsackie B5 virus also appeared to be similar but clear differences could be detected between these and the prototype (Faulkner) strain of the virus. The SVDV isolates were more closely related to the Faulkner strain than to the recent isolates of Coxsackie B5 virus. Perhaps of more importance, the Faulkner strain was more closely related to SVDV than it was to the recent Coxsackie B5 isolates. The significance of these observations in relation to the recent emergence of swine vesicular disease is discussed.

A study of immunoglobulin M antibody to measles, canine distemper, and rinderpest viruses in sera of patients with subacute sclerosing panencephalitis.

Seven boys were studied who had the clinical features of subacute sclerosing panencephalitis (SSPE) and whose brain histology was consistent with SSPE. Measles antigen was detected in the seven brains by the direct fluorescent antibody method. Three out of the seven boys had in their sera measles specific immunoglobulin M (IgM) which was detected by the indirect fluorescent antibody method, and the cell receptors for it were acetone stable. A prozone effect was noted in the sera of two patients. The absorption of one patient's serum with Staphylococcus aureus to reduce the titre of immunoglobulin G (IgG) removed the prozone effect. Two of the boys who had high titres of measles specific IgM also had serum IgM which reacted with canine distemper virus antigen but the titres were eightfold lower. None of the boys had detectable rinderpest specific IgM in their sera.