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Biomedical subjects

O Jarrett

Publications and source records attributed to O Jarrett.

At least 127 records · Page 7Linked to original sources
PubMed1981

The production of putative osteoclasts in tissue culture - ultrastructure, formation and behavior.

A system for culture of cat bone marrow produces multinucleate cells (50-100 nuclei) of large proportions (300 micrometer diameter). Scanning and transmission electron microscopy indicates that these cells (not virally induced syncytia) are true osteoclasts, which exhibit ultrastructural aspects of bone resorption (ruffled border and clear zones in TEM section, active spatulate cytoplasmic extensions in the SEM) even after 6 weeks culture on a plastic substratum. Observations have also been made regarding the formation of the multinucleate cells from apparently specific mononuclear precursors, and the behaviour of these cells on various substrata is also reported.

Animals↗
PubMed1980

Polypeptides of feline leukaemia virus: identification of p15(E) and p12(E).

Antiserum to the p15(E) polypeptide of Rauscher murine leukaemia virus (R-MuLV) precipitated two proteins from purified virions of feline leukaemia virus (FeLV) with apparent mol. wt. of 18500 and 155000 on SDS-polyacrylamide gels. These proteins have been designated p15(E) and p12(E), in line with the nomenclature for MuLV proteins. Like the analogous protein of MuLV, FeLV p15(E) was found to be disulphide-linked to the virion glycoprotein, gp70. FeLV p15(E) was sensitive to digestion of intact virus particles with the proteolytic enzyme, bromelain, indicating that this protein is on the outer surface of the virion. An analysis of cat sera for precipitating activity for FeLV p12(E) showed this only in sera from cats which had recovered from FeLV infection and had virus-neutralizing activity.

Animals↗
PubMed1980

Feline calicivirus induced polypeptides.

Analysis of feline calicivirus-infected cell extract for large and low molecular weight proteins revealed the presence, in submolar amounts, of a polypeptide of molecular weight 80,000 daltons which had no precursor-product relationship to the capsid proteins (mol. wt 68,000 and 14,000) synthesized in infected cells. Two other highly labelled non-structural polypeptides of molecular weights 80,000 and 40,000 daltons yet to be identified were also described.

Animals↗
PubMed1979

Diseases produced by feline caliciviruses when administered to cats by aerosol or intranasal instillation.

Specific pathogen free cats were infected by two feline calicivirus isolates of different plaque type, an extra-large plaque (ep) former and a minute plaque (mp) former. A comparison was made of the disease produced when these isolates were administered by either aerosol or direct intranasal instillation. With both isolates, aerosol infection produced lesions and gave rise to virus replication throughout the respiratory tract. The effects of intranasal infection were more confined to the upper respiratory tract and oropharynx. By both routes of infection the disease produced by the mp virus was clinically and pathologically less severe than that produced by the ep virus.

Administration, Intranasal↗
PubMed1978

The specificity of neutralizing antibodies to feline leukaemia viruses.

Feline leukaemia viruses (FeLV) of subgroups A (FeLV-A), B(FeLV-B) and C(FeLV-C) were examined by neutralization. The FeLV-A isolates were monotypic. By contrast, there was antigenic variation within subgroups B and C. There was also considerable cross-reactivity between subgroups. Thus, FeLV-A viruses showed weak cross-reactivity to the standard FeLV-C isolate; four of the subgroup B viruses were identical and cross-reactied with the standard FeLV-C, but not with FeLV-A or the fifth FeLV-B, and this latter virus weakly cros-reacted with FeLV-A but not with the FeLV-C; within subgroup C, one virus was indistinguishable from the standard FeLV-C strain but the other two were very similar to FeLV-A. Therefore, subgroup classification based on interference did not altogether correspond with neutralizing behaviour for subgroups B and C.

Animals↗
PubMed1978

Differential growth and transmission in cats of feline leukaemia viruses of subgroups A and B.

The outcome of infecting cats with FeLV of sub-groups A (FeLV-A) or B (FeLV-B) was different. After FeLV-A infection, virus was quickly recovered from the blood and oropharynx of most animals. Following infection with FeLV-B, only a small proportion of cats developed a viraemia, and this after a long interval. There was no evidence that FeLV-B was transmitted by contact. The result of infecting cats with mixtures of FeLV-A and B (FeLV-AB) was that to a large extent each virus operated independently. FeLV-A was recovered from the plasma first, in a high proportion of the cats, and FeLV-B appeared later but not in all cats. There was evidence of interaction, however, in that the proportion of cats which were viraemic with FeLV-B was greater following FeLV-AB infection than after infection with FeLV-B alone; also FeLV-B was transmitted by contact from cats excreting FeLV-AB. These results help to explain the apparent dependence of FeLV-B on FeLV-A under natural conditions and the frequency of occurrence of sugroups A and B in FeLV isolates.

Administration, Oral↗
PubMed1978

The frequency of occurrence of feline leukaemia virus subgroups in cats.

Feline leukaemia viruses (FeLV) were isolated from cats in Glasgow and New York with lymphosarcoma and from apparently healthy carrier cats. The subgroup composition of each isolate was determined. All isolates contained FeLV of subgroup A(FeLV-A) and a high proportion also contained subgroup B virus (FeLV-B). Virus of subgroup C (FeLV-C) was rare and occurred in association with FeLV-A and, in some isolates, with FeLV-B as well. The same pattern was observed in isolates from British and American cats. The frequency of FeLV subgroups was different in cats with lymphosarcoma and in healthy carrier cats. In cats with lymphosarcoma, 42% had FeLV-A and 58% had FeLV-AB; there was no obvious correlation between virus subgroup and type of disease. In FeLV-positive healthy cats, 65% had FeLV-A and 33% had FeLV-AB. FeLV-C was isolated only from cats with disease. The healthy carrier cats were from multiple-cat households (MCH). Two distinct types of FeLV-infected MCH were found: MCH-A in which the carrier cats yielded only FeLV-A, and MCH-AB in which cats with either FeLV-A or FeLV-AB were present. In MCH-AB half of the cats had FeLV-A and half had FeLV-AB. Overall, the proportion of cats in MCH which were viraemic with FeLV was 42%. However, there was a marked difference in the prevalence of carrier cats in each type of MCH: in MCH-A, 28% were FeLV-positive while in MCH-AB, 53% were viraemic.

Animals↗
PubMed1977

Horizontal transmission of feline leukemia virus under natural conditions in a feline leukemia cluster household.

Ten post-weanling 4-month-old cats, designated "tracers", were placed in a feline leukemia cluster household to determine the efficiency of horizontal transmission of feline leukemia virus (FeLV). The tracer cats were confirmed as negative for prior exposure to FeLV. Following the placement in the leukemia cluster environment, the tracer cats were serologically monitored at intervals of 3-6 weeks for a total period of 1 year. The tests employed included the detection of FeLV using fixed-cell immunofluorescence and the detection and titration of antibody to : (1) the feline oncornavirus-associated cell membrane antigen (FOCMA), as detected by membrane immunofluorescence; (2) viable FeLV, using serum neutralization; (3) virion core protein p30, using radioimmunoprecipitation; and (4) virion glycoprotein gp70, using radioimmunoprecipitation. All of the tracers had evidence of horizontal infection by FeLV, by several criteria. Seven of the 10 had virus that could be isolated from plasma. All of these 7 developed a terminal illness within 18 months; 3 developed aplastic anemia, 3 infectious peritonitis, and 1 lymphoma. The remaining 3 were negative for FeLV by both virus isolation and fixed-cell immunofluorescence. These 3 did, however, develop high antibody titers by all four criteria and they remained healthy throughout the examination period. These results clearly indicate that unprotected pros-weanling cats brought into a leukemia exposure household environment have a high risk of becoming infected with FeLV. Furthermore, a large proportion of the cats are at risk for development of persistent viremia and FeLV-related diseases.

Anemia, Aplastic↗
PubMed1976

An improved assay for feline leukaemia virus pseudotypes of murine sarcoma virus.

An assay is described for feline leukaemia virus pseudotypes of murine sarcoma virus which increased the virus titre by about 100-fold over conventional assays. The titre is independent of dilution and no secondary focus formation occurs. The assay may be used to study virus neutralization and to detect and type feline leukaemia virus in feline embryo cells by interference.

Adsorption↗
PubMed1976

Biology of feline leukemia virus in the natural environment.

The feline leukemia virus (FeLV) was discovered in 1964 in a cluster of cats with lymphosarcoma. The observed clustering of cases of feline lymphosarcoma suggested that FeLV was an infectious agent for cats. The development of a simple immunofluorescent test for FeLV permitted a seroepidemiological study to be undertaken on the distribution of the virus in cats living in their natural environment. Over 2000 cats were tested, and the results showed conclusively that FeLV is an infectious agent for cats. This finding has now been independently confirmed using three different test procedures. After the infectious nature of FeLV was discovered, a simple FeLV test and removal program was devised to control the spread of the virus in the natural environment. The spread of FeLV was controlled in 45 households by removing the FeLV-infected cats, while in 25 households, where the infected cats were left in contact with the uninfected cats, 12% of the uninfected cats became infected. The ultimate control of FeLV awaits the development of an effective FeLV vaccine, which now seems feasible since we have already experimentally immunized some cats with attenuated FeLV. Although FeLV is infectious for cats there is no evidence that FeLV can infect humans.

Animals↗
PubMed1975

Vaccination against feline leukaemia virus using a cell membrane antigen system.

Cats inoculated with live feline lymphoblastoid cells of the FL74 line developed high titres of antibody to feline oncornavirus-associated cell membrane antigen (FOCMA). Eight cats were subsequently challenged with a large dose of feline leukaemia virus (FeLV) of a highly pathogenic strain. All resisted infection while 10 cats given the challenge virus alone became infected. The FeLV produced by FL74 cells was shown to be of extremely low infectivity in cats and in cultured feline cells. Cats inoculated with either FL74 cells or virus purified from them did not become infected. The purified virus did not induce FOCMA antibody in cats not previously exposed to FeLV. The fact that FL74 cells are highly immunogenic, but produce virus of low infectivity, is of value in devising vaccines against FeLV. Cats were also inoculated with FL74 cells which had been inactivated with paraformaldehyde. They developed FOCMA antibody, reaching a peak titre of 256, and no virus could be cultured either from the vaccine preparations or from the tissues of the cats.

Animals↗