Search PubMed⌕ Search

Biomedical subjects

M J Studdert

Publications and source records attributed to M J Studdert.

At least 91 records · Page 5Linked to original sources
PubMed1987

Virus and virus-like particles in the faeces of cats with and without diarrhoea.

Negative staining electron microscopy was used to identify viruses in 166 normal and 62 diarrhoeal faecal samples from 208 cats admitted to an animal shelter during a 16-month period (March 1984 to June 1985). On the basis of size and shape 7 distinct viral types were detected: 24 nm parvovirus-like particles, 30 nm astrovirus, 30 nm picornavirus-like particles, reovirus, rotavirus, coronavirus and a 75 nm "togavirus-like" particle. The incidence of these particles in the 208 cats was 11%, 7%, 6%, 0.4%, 5%, 1% and 1% respectively. Virus isolation studies using 40 of the faecal samples succeeded in isolating reovirus 1 in 2 cases. Immune electron microscope studies demonstrated the presence of antibody in a human serum to cat astrovirus, but failed to clarify the identity of the parvovirus-like particles and picornavirus-like particles, other than showing that some of the parvovirus-like particles were not related to feline panleukopenia virus. It was found that parvovirus-like particles, astrovirus, picornavirus-like particles, reovirus and rotavirus could be excreted by cats with normal faeces as well as cats with diarrhoeal faeces. Parvovirus-like particles, astrovirus, picornavirus-like particles and rotavirus could be excreted in high concentration in normal faeces. There was no simple relationship between age and diarrhoea in the population of cats studied. Age was not a critical factor in the excretion of parvovirus-like particles, astrovirus, picornavirus-like particles and rotavirus. The incidence of diarrhoea was not clearly associated with the seasons.

Age Factors↗
PubMed1987

Epidemiology of equine herpesvirus 2 (equine cytomegalovirus).

The epidemiology of equine herpesvirus 2 was examined by using restriction endonuclease DNA fingerprints to distinguish viruses isolated from two groups of horses. The first group consisted of three yearlings isolated from other horses but in contact with each other for 418 days, whereas the second comprised seven mares and their foals, which were sampled at monthly intervals from parturition until the foals were about 180 days old. There was a complex pattern of transmission, with 15 different viruses isolated from both groups. Four distinguishable viruses were isolated from the three yearlings by day 16 of quarantine, and by day 141 an additional two viruses were isolated. Up to five different viruses were isolated from one yearling. Although four repeat isolations of one virus from the nasal cavity of one yearling over 54 days indicated that equine herpesvirus 2 established persistent infection with constant shedding, most repeat isolations yielded distinguishable viruses. Identical viruses were isolated from the nasal cavity and leukocytes of one yearling and the nasal cavity and vagina of another, indicating that a particular equine herpesvirus 2 strain was not site specific. Although seven different viruses were isolated from the three yearlings throughout the quarantine period, two appeared to establish latent infections; one virus was not isolated until 141 days after quarantine, whereas the second was first isolated 16 days after quarantine and then for the second time, from the same horse, 402 days later. Multiple concurrent local infections were demonstrated by the isolation of two or more viruses from the same nasal swab.

Animals↗
PubMed1986

Equine herpesvirus genomes: heterogeneity of naturally occurring type 4 isolates and of a type 1 isolate after heterologous cell passage.

The restriction endonuclease DNA fingerprints of 20 low passage, epidemiologically unrelated isolates of equine herpesvirus 4 (equine rhinopneumonitis virus) showed considerable heterogeneity in certain fragments, the positions of which were assigned to quite restricted positions on the 141 kilobase (kb) genome. We note that the heterogeneity observed in the restriction endonuclease DNA fingerprints of EHV 1 (equine abortion virus) and of pseudorabies virus also tend to map to these same restricted regions. The restriction endonuclease DNA fingerprints of an EHV 1 strain was invariant using low (less than 1) multiplicity of infection during 20 passages in equine cells but when adapted to hamster cells developed an approximately 0.8 kb deletion in the unique short region of the genome between 8 and 11 passages.

Animals↗
PubMed1986

Variable sensitivity of a feline embryo cell line and of three kitten kidney cell cultures to feline herpes- and caliciviruses.

The number of plaques produced in a feline embryo (FEmb) cell line and in three independently derived kitten kidney (KK) cell cultures varied in a consistent and reproducible manner when each was inoculated with the same number of feline herpesvirus 1 (FHV1) plaque forming units (PFU); the three KK cells produced 2-9 times more plaques than FEmb cells. One of the three KK cells produced FHV1 plaques that were smaller in diameter than those FEmb cells. Each of the three KK cell cultures inoculated with the same number of FEmb cell PFU of a strain of feline calicivirus (FCV) produced different numbers of plaques; two of the three KK cell cultures produced 2-3 times more plaques than FEmb cells. The plaque diameter of FCV in the three KK cells was 30-50% smaller than the plaque diameter in FEmb cells.

Animals↗
PubMed1985

Parvovirus (feline panleucopaenia virus) plaque formation.

A plaque assay was developed for feline parvovirus (FPV; feline panleucopaenia virus) in a feline embryo (FEmb) cell line. Higher numbers and larger diameter plaques were obtained with a) seeding rates of 0.7 X 10(5) and 1.5 X 10(5) cells cf. 3 X 10(5) and 6 X 10(5) cells/well of 35 mm diameter, b) synchronised cells infected at the G1-S interface cf. nonsynchronised cells and c) 5 to 6 days incubation post inoculation. The plaque assay was standardised by using serum deprivation for 24 hours to synchronize cells, a seeding rate of 1.5 X 10(5) cells/35 mm diameter well, inoculation of virus 16 hours post seeding followed by 5 days incubation. The standardised assay gave consistent, reproducible results. A dose-response curve using the assay showed a linear, 45 degrees slope, relationship between plaque forming units and virus dilution which further verified the sensitivity and reliability of the assay. Plaques produced by "wild" type and plaque purified virus were invariably non uniform in diameter; diameter of plaques in fact followed a normal frequency distribution under standard assay conditions.

Animals↗
PubMed1985

Nylon wool column fractionation and characterisation of feline lymphocyte subpopulations.

Feline separated mononuclear cells (SMC) were obtained from peripheral blood by ficoll-diatrizoate gradient separation. SMC were further fractionated on nylon wool columns into nylon wool adherent cells (NWAC) and nylon wool effluent cells (NWEC). The three cell populations, SMC, NWAC and NWEC, were characterised using direct immunofluorescent staining for surface immunoglobulin (sIg) as a B cell marker and neuramidase treated guinea pig erythrocyte-rosette formation (E-rosettes) and mitogen-induced lymphocyte blastogenesis (LB) as possible T-cell markers. Feline SMC consisted of 30.1 +/- 4.0% sIg+ cells 36.6 + 5.4% E-rosette forming cells and 33.3% null cells i.e. cells which were sIg- and non E-rosette forming. Fractionation of SMC on nylon wool columns yielded NWEC which were significantly enriched for T cells in that they contained 68.6 +/- 2.9% E-rosette forming. Fractionation of SMC on nylon wool columns yielded NWEC which were significantly enriched for T cells in that they contained 68.6 +/- 2.9% E-rosette forming cells. NWAC were 51.0% +/- 10.8% sIg+, approximately 20% of cells were lost. The LB responsiveness of NWEC to concanavalin A (Con A) and phytonaemagglutinin-P (PHA-P) was enhanced compared to SMC. NWAC were non-responsive to Con A and PHA-P at all concentrations tested. It was concluded that nylon wool column fractionation of feline SMC was an efficient procedure for T cell enrichment and that the enriched cells retained the properties of E-rosette formation and blastogenesis by mitogens.

Animals↗
PubMed1985

Molecular epidemiology and pathogenesis of ruminant herpesviruses including bovine, buffalo and caprine herpesviruses l and bovine encephalitis herpesvirus.

Restriction endonuclease DNA fingerprints of herpesviruses isolated from 3 unrelated epidemics of bovine encephalitis are similar to each other and totally different from bovine herpesvirus 1 (BHV1). Herpesviruses, antigenically related to BHV1, isolated from goats and buffalo have distinct DNA fingerprints. We propose that bovine encephalitis herpesvirus is prototypic of a new bovine herpesvirus type and that alpha herpes viruses from individual ruminant species are species specific.

Animals↗
PubMed1985

Feline panleukopenia virus replicates in cells in which cellular DNA synthesis is blocked.

The components of the cell cycle for a feline embryo cell line were defined. Thymidine (6mM)-supplemented medium reversibly arrested cells 1 h into the S phase of the cell cycle and was used in a double blocking procedure to synchronize cells to the early S phase. The kinetics of feline panleukopenia virus replication in synchronized cells was studied by using (i) inclusion body formation, (ii) a plaque assay for cell-associated and cell-free virus under one-step growth conditions, (iii) an enzyme immunoassay for viral protein, (iv) electron microscopy of infected cells, and (v) the detection and identification of viral replicative form DNA by restriction endonuclease analysis. Parallel studies by each of these procedures of the replication of feline panleukopenia virus in cells in which a 6 mM thymidine block was maintained indicated that parvovirus replicated with essentially similar kinetics in both unblocked, synchronized cells and in cells in which the block was maintained. Accordingly, a 6 mM thymidine-supplemented medium, although it effectively blocks cellular DNA synthesis, does not block the replication of parvovirus.

Animals↗
PubMed1984

Molecular epidemiology and pathogenesis of some equine herpesvirus type 1 (equine abortion virus) and type 4 (equine rhinopneumonitis virus) isolates.

Representative strains of EHV isolated from an aborted foetus and from a horse with rhinopneumonitis in New Zealand had restriction endonuclease DNA fingerprints typical of those usually associated with these syndromes elsewhere and now designated EHV1 and 4 respectively. EHV1 was isolated from the brain and spinal cord of a 4-year-old gelding that died of myeloencephalitis. A mare on the same farm, at about the same time as the gelding developed myeloencephalitis, aborted and EHV1 was isolated from the tissues of the aborted foetus. Restriction endonuclease DNA fingerprints of the viruses isolated from myeloencephalitis and abortion were indistinguishable by Bam HI but were distinguishable using Bgl I, Pvu II, Xho I and Hind III. The restriction endonuclease DNA fingerprints of 3 EHV1 strains known to cause myeloencephalitis were compared with each other and with EHV1 strains not known to be associated with myeloencephalitis. The Bgl I Pvu II and Hind III DNA fingerprints of the 3 myeloencephalogenic strains appear distinguishable from non-myeloencephalogenic strains. Abortion was induced in a mare by intrauterine inoculation of EHV4. The Bam HI, Bgl I, Pvu II, Xho I and Hind III restriction endonuclease DNA fingerprints of the inoculum virus were indistinguishable from virus recovered from the foetus. It was concluded that passage of the virus through the foetus did not detectably alter the restriction endonuclease DNA fingerprint.

Abortion, Veterinary↗
PubMed1984

Viruses and virus-like particles in the faeces of dogs with and without diarrhoea.

Negative staining electron microscopy was used to identify viruses in 157 normal and 29 diarrhoeal faecal samples collected from 156 dogs admitted to an animal shelter during an 8 month period (March to October) in 1982. Seven distinct viral types were detected: 21-26 nm parvovirus-like particles, 28-31 nm astrovirus-like particles, a previously undescribed 34-35 nm "round" virus particle, coronavirus, coronavirus-like particles ( CVLP ), rotavirus and papova-like virus. Parvovirus-like particles alone were detected in 14 diarrhoeal and 50 normal faeces, astrovirus-like particles in 3 normal faeces, "round" viruses in 4 normal faeces, coronavirus in 2 diarrhoeal and 5 normal faeces, CVLP in one diarrhoeal and one normal faeces, rotavirus in 2 normal faeces, papova-like virus in one normal faeces, both parvovirus-like particles and coronavirus in 2 diarrhoeal and 2 normal faeces, parvovirus-like particles and rotavirus in one normal faeces and parvovirus-like and papova-like virus in one normal faeces. The significance of these findings in canine and human disease is discussed.

Animals↗
PubMed1984

Immunologic relationships between equine herpesvirus type 1 (equine abortion virus) and type 4 (equine rhinopneumonitis virus).

The specificity of selected immune responses to equine herpesvirus type 1 (EHV-1) and type 4 (EHV-4) was examined in 3 colostrum-deprived specific-pathogen-free foals. Single foals were vaccinated with inactivated EHV-1, inactivated EHV-4, or control cell lysate plus adjuvant followed by successive intranasal challenge exposures with EHV-1 and EHV-4 or with EHV-4 and EHV-1. Vaccination with inactivated virus preparations elicited cellular immune responses and antibody which were augmented by subsequent challenge exposures. Cellular immune responses, as measured by in vitro lymphocyte blastogenesis, were cross-reactive after foals were given either EHV-1 or EHV-4. Serum virus-neutralizing antibody responses were type-specific for foals given EHV-1, but were cross-reactive after EHV-4 administrations. It was concluded that diseases caused by EHV-1 and EHV-4 may be more effectively controlled with a bivalent vaccine containing both EHV-1 and EHV-4 than with the presently used monovalent vaccines based on EHV-1 alone.

Animals↗