Isolation and identification of bovid enteroviruses from free-living wild animals in Botswana.
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Biomedical subjects
N J Knowles
Publications and source records attributed to N J Knowles.
A serological classification of bovine enteroviruses.
Cross virus neutralization (VN), complement fixation (CF) and immunoprecipitation (IP) tests were employed to compare the seven currently recognized bovine enterovirus (BEV) serotypes with seven serologically distinct strains previously isolated in Great Britain and two other BEV from the United Kingdom. Based on criteria used to differentiate other human and animal picornavirus serotypes, it was discovered that BEV types 1, 4, 5 and 6 were related to each other and could be included in a single serotype. Types 3 and 7 were found to be identical, and related to serotype 2. All of the other nine BEV were included in either serotype 1 or 2. Not all of the strains in each serotype were identical and antigenic variants were designated as subtypes. Antigenic relationships not revealed by VN were demonstrated in CF and IP tests. Bovine enterovirus strains whose antisera had the broadest intratypic reactivity were suggested as prototypes. The two proposed BEV serotypes could also be distinguished by their ability to agglutinate erythrocytes. Guinea pig erythrocytes were agglutinates by both serotypes while sheep red cells only reacted with serotype 1.
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A study of antigenic variants of foot-and-mouth disease virus by polyacrylamide gel electrophoresis of their structural polypeptides.
Twenty-nine foot-and-mouth disease (FMD) type A virus strains, previously classified serologically as distinct subtypes were analysed by polyacrylamide gel electrophoresis (PAGE) to determine the extent of variation in the pattern of the structural polypeptides and to evaluate the technique as an aid to existing subtyping techniques. The majority of the subtypes examined had distinct polypeptide patterns, however, some variation also occurred between strains within a subtype. The position of VP2(1B) and VP3(1C) was often unchanged in different strains within a subtype and between geographically related subtypes over long periods of time. Changes in the position of VP1(1D) were also observed within a subtype. The technique was considered to be of value for the screening of isolates prior to conventional serological subtyping procedures and in the tracing of the possible origin of FMD outbreaks.
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A serological and biochemical study of new field isolates of foot-and-mouth disease virus type A in Peru, 1975 to 1981.
Three foot-and-mouth disease virus type A isolates recovered from field outbreaks in the Department of San Martin, Peru, during the period 1975 to 1981 were compared with each other, and the South American vaccine strains A24 and A27, by complement fixation (CF), virus neutralization (VN) and polyacrylamide gel electrophoresis (PAGE). Complement fixation and VN tests gave comparable results distinguishing the field isolates from each other and from the vaccine strains. Analysis of the structural polypeptides by PAGE also showed clear differences between all the viruses examined. Samples from tissue culture passaged and mouse adapted strains of one of the field isolates gave identical patterns in PAGE, but differences were observed in the polypeptide pattern of the A24/BRA/55 strain and the Peru vaccine strain, which were serologically indistinguishable. Results illustrate a continued antigenic variation in an endemic area where vaccination has been used; however, asymmetric serological reactions between the A24 vaccine strain and the most recent field isolate indicated that a vaccine incorporating A24 should still give adequate protection.
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Comparative studies of United Kingdom isolates of swine vesicular disease virus.
The characteristics of four United Kingdom isolates of swine vesicular disease (SVD) virus from 1981 to 1982 have been compared with those of an isolate obtained from the first outbreak of swine vesicular disease diagnosed in the United Kingdom in 1972. When the virus structural proteins were examined by polyacrylamide gel electrophoresis the four isolates from 1981-82 all had the same polypeptide pattern, which was different from that of the 1972 isolate. Immunodiffusion tests with the 1972 isolate and one 1982 isolate did not reveal any antigenic difference between the viruses but minor antigenic differences were shown by cross-neutralisation tests between the 1972 isolate and the four isolates from 1981-82. In experimentally infected pigs the 1972 isolate produced typical SVD lesions whereas the four more recent SVD viruses produced only very mild clinical disease. Clinical lesions scored numerically were four- to 10- and five- to 11-fold higher at seven and 14 days after infection for pigs infected with the 1972 isolate than with the four isolates from 1981-82. The serum of pigs infected with the 1972 isolate contained significantly higher levels of neutralising antibody than those of pigs infected with more recent isolates. The antibody titres of pigs with only primary lesions ranged from log10 1.9 to 2.8 and one clinically normal pig had a titre of log10 2.4 at 14 days after infection. Attention is drawn to the implication of these findings for SVD control policies based only on the recognition and reporting of clinical disease.
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Differentiation of porcine enterovirus serotypes by complement fixation.
A complement fixation test in microtitre plates for the differentiation of porcine enterovirus serotypes is described, employing guinea pig antisera prepared using inactivated purified viruses. Eleven porcine enterovirus serotypes and swine vesicular disease virus were compared and clearly distinguished from each other. In addition, 71 porcine enterovirus strains and isolates were tested and each was identified as belonging to one of the 11 serotypes.
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Classification of porcine enteroviruses by antigenic analysis and cytopathic effects in tissue culture: description of 3 new serotypes.
Porcine enteroviruses isolated in the United Kingdom between 1972 and 1976 were compared with the 8 serotypes previously described and with human coxsackie B virus types 1 to 6 for ability to grow in different cell lines. This allowed the classification of all strains into 3 broad groups according to type of cytopathic effect in IBRS-2 cells and further subdivision on the basis of production of cytopathic effect in BHK 21, HeLa and VERO cells. None of the porcine enterovirus strains was neutralized by antisera to human enteroviruses (Lim Benyesh-Melnick Pools) with the exception of swine vesicular disease virus, which was neutralised by coxsackie B5 antiserum. Antisera prepared either in gnotobiotic pigs or in guinea pigs against the 8 porcine enterovirus serotypes failed to neutralize 9 isolates which could be classified into 3 new serotypes, for which Nos. 9, 10 and 11 are proposed. Guinea pig sera could be used as an alternative to gnotobiotic pig sera for type differentiation.
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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.
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Isolation and identification of porcine enteroviruses in Great Britain, 1979 to 1980.
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Animals↗
Comparison of the pathogenic, antigenic and molecular characteristics of two encephalomyocarditis virus (EMCV) isolates from Belgium and Greece.
The pathogenicity of two porcine encephalomyocarditis virus (EMCV) isolates for sows in gestation and young piglets was studied. One virus originated from a case of reproductive failure in pigs in Belgium and the other from a case of acute myocarditis in pigs in Greece. Sows in the mid-gestation period and one- to two-month old piglets were inoculated with each isolate. The molecular relationship between both isolates was studied by determining the nucleotide sequence located across the junction of the 1C and 1D capsid-coding genes. Antigenic analysis was performed using a panel of 35 monoclonal antibodies raised against an Italian field isolate of EMCV. All three approaches revealed differences between both isolates and also confirmed that there was no link between the two outbreaks of disease.
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