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N J Knowles

Publications and source records attributed to N J Knowles.

At least 55 records · Page 3Linked to original sources
PubMed1994

Experimental transmission of foot-and-mouth disease virus from carrier African buffalo (Syncerus caffer) to cattle in Zimbabwe.

Four female cattle and three male African buffalo (Syncerus caffer) which were free of foot-and-mouth disease (FMD) virus were held together on an island in Lake Kariba, Zimbabwe. The buffalo were experimentally infected with FMD virus type SAT2, developed generalised disease and became virus carriers. While the buffalo were in the acute phase of the disease the susceptible contact cattle did not show lesions, no virus was recovered from them and they did not develop serum antibodies. However, five months later the cattle developed severe foot-and-mouth disease. Direct nucleotide sequencing of the virus used to infect the buffalo and of the virus from the in-contact cattle showed that the two isolates were almost identical. The results suggest that in nature it is possible for the virus to be transmitted from buffalo to cattle under the influence of factors not yet defined, and that there was very little change in the nucleotide sequence of the virus during the carrier period of five months.

Amino Acid Sequence↗
PubMed1994

A comparative study of serological and biochemical methods for strain differentiation of foot-and-mouth disease type A viruses.

Three serological and three biochemical methods were used to compare five field isolates of foot-and-mouth disease virus (FMDV) from Western India with nine reference vaccine strains and five field isolates from other countries. The serological tests (liquid-phase ELISA and virus neutralization) were able to distinguish between the three reference vaccine strains examined, but the five Indian field isolates reacted poorly with antisera produced against these vaccine strains. Analysis of monoclonal antibody (mAb) data was difficult to interpret although clearly the field isolate A/IND/5/87 reacted to a lesser extent with one of the mAb panels (A10/Holland/42) than the other four Indian isolates. The A22/Iraq/24/64 mAbs did not react with any of the Indian field isolates and only significantly with one of the reference vaccine strains, A/IND/57/79. Polyacrylamide gel electrophoresis distinguished the reference vaccine strains from each other and from the field isolates. Additionally, one of the Indian isolates (A/IND/5/87) could be differentiated from the other four. Electrofocusing showed similarities between the reference vaccine strain A22/Iraq/24/64 and three of the Indian field isolates (A/IND/1/87, A/IND/2/87 and A/IND/3/87), however, A/IND/4/87 and A/IND/5/87 were distinct. Nucleotide sequencing showed that the isolates A/IND/1/87, A/IND/2/87 and A/IND/3/87 were very closely related to each other and related to A/IND/4/87, however, A/IND/5/87 was different.

Amino Acid Sequence↗
PubMed1994

Analysis of mixed foot-and-mouth disease virus infections in Saudi Arabia: prolonged circulation of an exotic serotype.

Plaque purification of foot-and-mouth disease (FMD) type O viruses isolated from cattle in Saudi Arabia showed the presence of mixed serotype infections. Sixteen out of 31 samples collected between 1985 and 1991 also contained Asia 1 virus, a serotype which had previously only been isolated from a single outbreak in that country in 1980. Nucleotide sequences of the Asia 1 component of all these samples revealed little variation and showed that they were closely related to both a Russian lapinized vaccine virus strain (Asia 1/Tadzhikistan/64), and to a field isolate from Turkey (Asia 1/TUR/15/73). Although mixed FMD infections have been observed previously this is a first report of a serotype, considered to be exotic to a country, co-existing undetected for an extended period of time.

Animals↗
PubMed1994

Genetic relationships between foot-and-mouth disease type Asia 1 viruses.

The sequence of 165 nucleotides at the 3' end of the 1D (VP1) gene of foot-and-mouth disease (FMD) virus was determined for 44 type Asia 1 strains isolated from throughout Asia between 1954-92. Analysis of the relationships between the virus genomes showed epidemiological links not previously evident. The possible origin of the only outbreak of FMD Asia 1 to have occurred in Europe, in Greece in 1984, was identified because the nucleotide sequence of this virus was closely-related to the sequences of those present in the Middle East between 1983-5. Variation in the region sequenced was not as great as that seen in the other FMDV serotypes and all viruses shared greater than 85% nucleotide identity. Thus all the virus isolates examined were considered to belong to a single genotype. A database of Asia 1 virus sequences has been established which will facilitate the rapid analysis of new outbreaks strains.

Amino Acid Sequence↗
PubMed1993

Evidence for different lineages of rinderpest virus reflecting their geographic isolation.

Sequence analysis of part of the fusion protein gene from recent isolates of rinderpest virus revealed that distinct lineages of the virus exist which reflect the geographical location of their isolation in Africa and Asia. Current strains circulating in Kenya and Sudan were most similar, both in terms of nucleotide sequence and pathogenic nature, to viruses isolated in Egypt and in Nigeria in 1983/1984 and they were quite distinct from an East African isolate (RBT-1) from the 1960s. Two older isolates of the virus, the Japanese avianized/lapinized vaccine strain dating from the 1930s and the Old Kabete strain dating from 1911, each differed considerably from the other viruses. The sequence data were derived from the region where the precursor protein is cleaved to yield the biologically active F1/F2 heterodimer; all strains analysed had a highly basic connecting peptide which is required for efficient cleavage by endogenous host cell proteases. No correlation was found between amino acid changes at this site and the rinderpest virus pathogenicity unlike the association reported for Newcastle disease virus.

Africa↗
PubMed1993

Complete nucleotide sequence of a coxsackie B5 virus and its relationship to swine vesicular disease virus.

We report the first complete nucleotide sequence of the picornavirus coxsackievirus B5 (CB5), strain 1954/UK/85, an isolate from a case of hand-foot-and-mouth disease. We have compared the sequence with those of other coxsackie B viruses, coxsackievirus A9, poliovirus and swine vesicular disease virus (SVDV). The genes encoding the three major capsid proteins are most closely related to those of SVDV but the 5' and 3' noncoding regions and the P3 gene are more similar to the corresponding regions in the other coxsackie B viruses than to those of SVDV. These observations are considered in the light of the antigenic and biochemical relationships between SVDV and CB5.

Amino Acid Sequence↗
PubMed1993

Field and laboratory analysis of an outbreak of foot and mouth disease in Bulgaria in 1991.

In July 1991, an outbreak of foot and mouth disease (FMD) occurred near Stefan Karadjovo village in Boliarovo (south-east Bulgaria, close to the Turkish border). The virus isolated was identified in Bulgaria as serotype O and this was subsequently confirmed by the World Reference Laboratory for Foot and Mouth Disease in Pirbright (United Kingdom). Serological studies using bovine sera and monoclonal antibody analysis were made. In addition, the sequence of approximately 170 nucleotides at the 3' end of the 1D gene was determined for the field isolate and for vaccine strains used in Bulgaria. These were compared with other sequences of type O FMD viruses from outbreaks in the Middle East. Serum samples were taken from domestic animals in the region close to the outbreak and examined for anti-FMD virus antibodies to assess the extent (if any) of spread of the virus before or after the outbreak. No evidence of infection was found in these animals. The virus involved in the Bulgarian outbreak was antigenically similar to the O1 vaccine strains but probably did not originate from these strains. The virus was closely related genetically to a group of viruses isolated in the Middle East since 1987, suggesting that it may have been introduced into Bulgaria from an area in the Middle East by unidentified means.

Animals↗
PubMed1992

Genetic relationships between southern African SAT-2 isolates of foot-and-mouth-disease virus.

Sequencing of part of the 1D gene of foot-and-mouth disease virus was used to determine the relationships between SAT-2 viruses isolated from outbreaks which occurred in cattle in Zimbabwe and Namibia and in impala in South Africa between 1979 and 1989. The results demonstrated that the outbreaks in different countries were unrelated. Surprisingly close relationships were shown between all SAT-2 viruses isolated from cattle in Zimbabwe since 1983 but the two major epizootics which occurred in 1989 were caused by viruses which were clearly different. Conversely, two apparently unrelated outbreaks in impala in South Africa were caused by viruses which could not be distinguished.

Africa, Southern↗
PubMed1992

Evolution of the capsid protein genes of foot-and-mouth disease virus: antigenic variation without accumulation of amino acid substitutions over six decades.

The genetic diversification of foot-and-mouth disease virus (FMDV) of serotype C over a 6-decade period was studied by comparing nucleotide sequences of the capsid protein-coding regions of viruses isolated in Europe, South America, and The Philippines. Phylogenetic trees were derived for VP1 and P1 (VP1, VP2, VP3, and VP4) RNAs by using the least-squares method. Confidence intervals of the derived phylogeny (significance levels of nodes and standard deviations of branch lengths) were placed by application of the bootstrap resampling method. These procedures defined six highly significant major evolutionary lineages and a complex network of sublines for the isolates from South America. In contrast, European isolates are considerably more homogeneous, probably because of the vaccine origin of several of them. The phylogenetic analysis suggests that FMDV CGC Ger/26 (one of the earliest FMDV isolates available) belonged to an evolutionary line which is now apparently extinct. Attempts to date the origin (ancestor) of the FMDVs analyzed met with considerable uncertainty, mainly owing to the stasis noted in European viruses. Remarkably, the evolution of the capsid genes of FMDV was essentially associated with linear accumulation of silent mutations but continuous accumulation of amino acid substitutions was not observed. Thus, the antigenic variation attained by FMDV type C over 6 decades was due to fluctuations among limited combinations of amino acid residues without net accumulation of amino acid replacements over time.

Amino Acid Sequence↗
PubMed1991

Evaluation of a trapping ELISA for the differentiation of foot-and-mouth disease virus strains using monoclonal antibodies.

A trapping enzyme-linked immunosorbent assay (ELISA) has been evaluated for the differentiation of foot-and-mouth disease virus (FMDV) strains using a panel of seven anti-serotype O monoclonal antibodies (MAbs). The variation of results within and between tests performed on the same day and on different days was examined using three strains of FMDV. Criteria for establishing antigenic differences between the strains as defined by the individual MAbs are proposed based on the variability measured, which can be used as standards by workers performing this test with other MAbs and FMDV strains.

Animals↗
PubMed1990

The complete nucleotide sequence of a pathogenic swine vesicular disease virus.

The nucleotide sequence of a swine vesicular disease virus (SVDV) strain that is pathogenic for pigs has been determined and compared with that of a non-pathogenic strain of SVDV, as well as a number of other enteroviruses. It shows only 98 base changes in comparison with a non-pathogenic strain of SVDV (Inoue et al., 1989, J. Gen. Virol. 70, 919-934). Fourteen of these nucleotide differences between the pathogenic and the non-pathogenic SVDV strains occur in the 5' non-coding region which, by analogy with the other picornaviruses, has been implicated in the efficiency with which the RNA is employed as mRNA. Additional differences found throughout the coding regions are largely conservative in nature. A number of residues are discussed as candidates for determinants of pathogenicity. This sequence has been submitted to the PIR database and has accession number A30061.

Amino Acid Sequence↗
PubMed1990

Antigenic analysis of serotype O foot-and-mouth disease virus isolates from the Middle East, 1981 to 1988.

During the period 1981-88 foot-and-mouth disease virus (FMDV) serotype O continued to be isolated from outbreaks in the Middle East. Field isolates submitted to the World Reference Laboratory have been examined in relation to reference strains by either complement fixation, virus neutralization or enzyme-linked immunosorbent assays. Most isolates were related to the European type O1 reference strains although strains emerging in late 1987 and 1988 were more closely related to O1/Manisa. In addition, FMDV isolates from Libya in 1981 and Syria in 1987 have shown very little relationship to these reference strains, although evidence of their persistence and spread has not been demonstrated.

Animals↗
PubMed1990

The complete nucleotide sequence of enterovirus type 70: relationships with other members of the picornaviridae.

Enterovirus type 70 (EV70) is the causative agent of acute haemorrhagic conjunctivitis and may also give rise to a rare neurological complication closely resembling poliomyelitis. The complete nucleotide sequence of the genome of EV70 has been determined from cDNA cloned in Escherichia coli. The genome consists of a 5' non-coding region of 726 nucleotides (nt), a long open reading frame of 6582 nt and a 3' non-coding region of 82 nt prior to the poly(A) tract. Comparison of the nucleotide sequence and the predicted amino acid sequence of the polyprotein with those published for other enteroviruses reveals sufficiently high similarity to predict antigenic regions and polyprotein cleavage sites. The P1 region of EV70 is as similar to those of the entero- as to those of the rhinoviruses, whereas the P2 and P3 regions are more closely related to the coxsackie B and swine vesicular disease viruses than other entero- or rhinoviruses.

Amino Acid Sequence↗
PubMed1990

A study of antigenic variants of foot and mouth disease virus type A in India between 1977 and 1985.

The structural polypeptides of thirty-three field isolates of foot and mouth disease virus (FMDV) collected in India between 1977 and 1985 were analysed by SDS-polyacrylamide gel electrophoresis. They were placed in eleven groups based on their patterns and compared with results of conventional serological (virus neutralisation and complement fixation) tests. Variation occurred in the structural proteins of the viruses isolated between 1977 and 1981; however, the polypeptide patterns of viruses isolated in 1984 and 1985 were identical.

Animals↗
PubMed1988

FRAGMAP--a program for restriction site map comparison.

A program is described which aligns pairs of linear restriction site maps using an algorithm which maximizes the number of coincident sites through the addition of extra 'padding' fragments; and makes maps of the non-conserved sites between pairs and triplets of input maps. A range of display facilities, hardcopy functions and database management routines are also included. The program runs on a stand-alone microcomputer, and is stored along with a database of several hundred files on a single floppy disc.

Copying Processes↗
PubMed1988

Serological and biochemical analysis of some recent type A foot-and-mouth disease virus isolates from the Middle East.

In 1986 and 1987 foot-and-mouth disease virus (FMDV) serotype A was isolated from outbreaks of disease in Saudi Arabia and Iran. Selected virus isolates were antigenically distinct from the prototype A22 virus strain (A22/Iraq/64), but were serologically related to each other. However, polyacrylamide gel electrophoresis showed that whilst the respective Saudi Arabian structural polypeptides were homogeneous, those from an Iran isolate were distinct. Direct sequencing of part of the P-1D (VP1) gene demonstrated considerable difference in nucleotide homology between the two groups of viruses; the Saudi Arabian viruses were closely related to each other but only distantly related to both the A22 prototype virus strain and the Iranian virus isolate. The latter viruses were only slightly more closely related to each other. Thus there appeared to be at least two distinct FMDV type A variants co-circulating in the Middle East, both of which differed considerably from the classical A22 subtype.

Animals↗