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Biomedical subjects

R P Kitching

Publications and source records attributed to R P Kitching.

At least 73 records · Page 4Linked to original sources
PubMed1994

Use of a recombinant antigen in an indirect ELISA for detecting bovine antibody to capripoxvirus.

The gene coding for the capripoxvirus structural protein P32 was cloned, expressed in Escherichia coli as a fusion protein with glutathione-S-transferase, and purified on glutathione Sepharose. An indirect enzyme linked immunosorbent assay (ELISA) using this antigen was developed to screen bovine sera for antibodies to capripoxvirus. Sequential serum samples from experimentally infected animals tested by ELISA and by virus neutralisation test (VNT) showed that the ELISA was more sensitive and detected antibodies to capripoxvirus earlier post-infection than the VNT.

Animals↗
PubMed1994

A hemi-nested PCR assay for the detection and identification of vesicular stomatitis virus nucleic acid.

This paper is the first to describe the development of a hemi-nested PCR assay for the detection of vesicular stomatitis virus (VSV) nucleic acid. This assay was developed as it combines high sensitivity for virus genome detection with the identification of the external amplification product in the reamplification step, thus confirming the specificity of the reaction. The assay did not depend on the presence of infectious virus in samples, as demonstrated by its detection of VSV in blood samples which were non-infectious in tissue culture. One further advantage was that the VSV-New Jersey and VSV-Indiana serotypes could be differentiated through the selective use of the appropriate hemi-nested primer. This assay is ideal for the study of VSV pathogenesis and persistence.

Animals↗
PubMed1994

Western blot analysis of virus-specific antibody responses for capripox and contagious pustular dermatitis viral infections in sheep.

This paper reports the development and evaluation of serological tests for the differentiation of antibodies in animals infected with capripox and parapox viruses. Agar-gel immunodiffusion tests using sera from sheep with naturally-acquired infections and from sheep experimentally inoculated with orf or capripox viruses showed cross reactions. Virus-specific antibody responses to structural proteins of the viruses were analysed by Western-blot analysis. This analysis readily differentiated the infections as either capripox or contagious pustular dermatitis. The antibody responses to the 32 kDa and 26 kDa proteins of capripoxvirus provided a firm basis for differentiation.

Animals↗
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↗
PubMed1993

Immunisation of cattle with a recombinant vaccinia vector expressing the haemagglutinin gene of rinderpest virus.

The efficacy of a recombinant rinderpest vaccine, constructed by inserting the rinderpest virus haemagglutinin gene into attenuated vaccinia virus, LC16mO strain, was tested in cattle. After subcutaneous inoculation of 10(8) plaque-forming units (pfu) of the recombinant vaccine, neither palpable skin lesions nor increases in body temperature were observed, indicating the absence of detectable clinical reactions. All the vaccinated cattle were completely protected from challenge with the Saudi 1/81 strain of virulent rinderpest virus. Contact control cattle housed in the same pen with the vaccinated animals did not develop antibodies to rinderpest or vaccinia viruses, and developed typical clinical signs of rinderpest after challenge with virulent rinderpest virus, indicating that there was no contact transmission of the recombinant virus. The 50 per cent protective doses of the vaccine, estimated by the mortality and morbidity rates respectively. were 10(4) and 10(5) pfu. To observe the effect of pre-existing immunity to vaccinia virus on the efficacy of the vaccine, cattle inoculated with the Lister strain of vaccinia virus three weeks earlier, were vaccinated with the recombinant virus. These animals developed antibodies to rinderpest virus and were protected from challenge with virulent rinderpest virus, showing that the vaccine was effective in animals already immune to vaccinia virus. The effectiveness and safety of the vaccine demonstrated in this study suggest that it has potential as a new vaccine against rinderpest.

Animals↗
PubMed1993

Single capripoxvirus recombinant vaccine for the protection of cattle against rinderpest and lumpy skin disease.

A recombinant capripoxvirus has been constructed containing a full-length cDNA of the fusion protein gene of rinderpest virus. The gene was inserted in the thymidine kinase gene of the capripox genome under the control of the vaccinia virus major late promoter p11 together with the Escherichia coli gpt gene in the opposite orientation under the control of the vaccinia early/late promoter p7.5. A vaccine prepared from this recombinant virus protected cattle against clinical rinderpest after a lethal challenge with a virulent virus isolate. In addition, the vaccine protected the cattle against lumpy skin disease.

Animals↗
PubMed1993

Detection of foot-and-mouth disease viral sequences in clinical specimens and ethyleneimine-inactivated preparations by the polymerase chain reaction.

The polymerase chain reaction method (PCR) has been applied to the diagnosis of foot-and-mouth disease viral RNA in tissues and, particularly, oesophageal-pharyngeal fluid (probang) samples from cattle. Using primer sets which corresponded to conserved regions of the VP1 sequence of the viral genome, it was possible to amplify sequences regardless of the serotype/strain of the virus. In comparison with infectivity assays, the PCR was generally more sensitive although there were a number of examples where only infectivity was detectable. In experiments with uninfected probang samples deliberately seeded with a dilution series of virus, the PCR proved to be approximately 10(4) times more sensitive than infectivity assays. This greater sensitivity was attributed, in part, to the ability of the PCR to amplify specifically from non-infectious RNA preparations. This enabled the identification, by sequencing, of viral RNA from chemically inactivated virus concentrates typical of those used for commercial vaccine production. Amplification of specific PCR products was also achieved with virus eluted from commercial vaccine, including preparations which had been stored for more than 10 years at 4 degrees C. The PCR technique is of considerable value, therefore, both as a complement to infectivity assays and as a powerful tool in vaccine-associated studies.

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↗
PubMed1993

Use of the polymerase chain reaction in differentiating rinderpest field virus and vaccine virus in the same animals.

In 1991, a disease with clinical signs indicative of rinderpest was reported in yaks in the former Soviet Union, near the border with Mongolia. At the peak of the epizootic, mortality among affected yaks was 32-42% in adults and 65% in animals less than one year old. Pathological samples were examined independently at two institutes in Russia. Both institutes confirmed the presence of rinderpest using complement fixation, agar gel diffusion and immunoassays. Since vaccination had been initiated to control an outbreak of a similar disease several months earlier, the later cases were possibly due to the vaccine and field rinderpest may not have been present. However, the disease had occurred in non-vaccinated animals and these were then vaccinated against the disease. Tissue samples obtained from these animals, which were examined at the Pirbright Laboratory using gel diffusion assays and specific nucleic acid probes, were found to be positive for rinderpest antigen and nucleic acid. Ribonucleic acid derived from the post-mortem tissue samples was amplified using the polymerase chain reaction and rinderpest-specific primers. Sequence analysis of the amplified deoxyribonculeic acid from the samples revealed the presence of two distinct virus strains, one identical to the Plowright rinderpest tissue culture vaccine and the other related to field strains of rinderpest virus circulating in Asia and the Middle East.

Animals↗
PubMed1992

A review of foot and mouth disease in Nepal.

Foot and mouth disease (FMD) causes substantial economic losses to the predominantly agricultural community of the Kingdom of Nepal. FMD is endemic in the country and four of the seven serotypes of FMD virus have been isolated (O, A, C and Asia 1). The epidemiology of FMD and the factors which play a role in its prevalence and spread are outlined. The National Epidemiological Laboratory for FMD has been established in Kathmandu and its diagnostic capabilities and activities are described. The important points to be considered in the formulation of any future regional or national control programme for FMD in Nepal are discussed.

Animals↗
PubMed1990

Use of inactivated foot-and-mouth disease virus antigen in liquid-phase blocking ELISA.

A liquid-phase blocking ELISA is used by the World Reference Laboratory for Foot-and-Mouth Disease for the quantification of antibodies to foot-and-mouth disease virus. The potential for using inactivated FMDV antigens in the assay has been assessed by titrating bovine convalescent sera to all seven serotypes and comparing the titres obtained with live or inactivated antigens. The titres were similar indicating that either live or inactivated antigens can be used in the liquid-phase blocking ELISA. Removing the need to use live antigens in tests for FMD antibody would reduce disease security risk and widen the acceptability of kits for FMD antibody detection and assay.

Animals↗
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↗
PubMed1989

The characterization of African strains of capripoxvirus.

Isolates of capripoxvirus collected from sub-Saharan Africa were compared in sheep, goats and cattle and by restriction endonuclease digestion of their purified DNA. Biochemical techniques were used to precisely identify strains of capripoxvirus for epidemiological investigations. Strains of capripoxvirus infecting cattle have remained very stable over a 30-year period and are closely related to strains recovered from sheep in Africa.

Africa↗
PubMed1989

Poxvirus genetic recombination during natural virus transmission.

We have compared detailed physical maps of the genomes of four capripoxvirus isolates, representing four capripoxvirus genome types. The comparisons strongly suggest that the progenitor of one of these isolates arose by genetic recombination between members of two of the other three types.

Animals↗
PubMed1989

Transmission of foot-and-mouth disease by vaccinated cattle following natural challenge.

Cattle vaccinated with a conventional monovalent type O1 foot-and-mouth disease (FMD) vaccine were challenged between four and 21 days after vaccination by short-term exposure to homologous airborne virus produced by pigs. Transmission was then assessed by housing susceptible cattle with the vaccinated animals and testing and observing all the animals for signs of infection and clinical disease. All 18 cattle vaccinated three weeks before challenge resisted clinical disease and although four contracted subclinical infection, there was no transmission to susceptible cattle in contact. One of the two groups of cattle vaccinated two weeks previously transmitted subclinical infection, but not disease, to susceptible animals housed with them from day 0 after challenge. Subclinical infection was manifested by a transient viraemia which was not followed by a detectable circulating antibody response. Shorter periods (seven or four days) from vaccination to challenge resulted in transmission of disease from clinically normal vaccinated to in-contact animals in one of two experiments. The severe challenge presented by the diseased in-contact animals than overwhelmed the immunity of the vaccinated animals. The results indicate that during emergency vaccination programmes it is advisable to vaccinate all FMD-susceptible animals within the vaccination zone and that at the outer boundary of the zone vaccinated animals should be kept separated from unvaccinated animals for at least three weeks.

Animals↗
PubMed1988

Rapid correlation between field isolates and vaccine strains of foot-and-mouth disease virus.

Antigenic relationships between field isolates of foot-and-mouth disease virus and available vaccine strains can be rapidly determined by ELISA. The most suitable vaccine strain to control an outbreak caused by the field isolate can then be quickly identified. The classical method of subtyping strains of foot-and-mouth disease virus should be replaced with a nomenclature which describes the relationship between a strain and the most antigenically closely related vaccine strain.

Animals↗
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↗