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Biomedical subjects

M H Lucas

Publications and source records attributed to M H Lucas.

36 records · Page 2Linked to original sources
PubMed1982

Detection of bovine leukosis virus in bronchoalveolar lung washings and nasal secretions.

Cattle and sheep persistently infected with bovine leukosis virus (BLV) were studied for the presence of the virus in bronchoalveolar lung washings and nasal secretions. The virus was demonstrated in the cellular fraction of the lung washings in six out of nine cattle and in one out of six sheep. In no instance was bovine leukosis isolated from the cell-free bronchoalveolar lung washings. The virus was isolated from the nasal secretion of only one of six naturally infected milking cows despite frequent sampling; the virus-infected nasal secretion was from a sick 10-year-old cow. Bovine leukosis virus was not isolated from cellular fractions of nasal secretions.

Animals↗
PubMed1982

Safety and efficacy of live and inactivated infectious bovine rhinotracheitis vaccines.

Two commercial live virus infectious bovine rhinotracheitis (IBR) vaccines for intranasal administration and an inactivated polyvalent calf pneumonia vaccine were compared for safety and efficacy in calves against experimental IBR infections. All three products were clinically safe for use in young calves; a mild, transient, febrile response was induced by one of the live vaccines. Vaccinal virus was recovered for up to 16 days after vaccination from nasal secretions of all calves given live vaccine. Both live vaccines stimulated a serum neutralising antibody response, but the inactivated vaccine failed to elicit any serological response. Following intranasal challenge four months after the first dose of vaccine, all live virus vaccinates remained systemically healthy. A slight nasal discharge and a few rapidly healing ulcers of the nasal mucosa were the only abnormalities observed. Both the group given the inactivated vaccine and the unvaccinated controls developed clinical IBR with pyrexia, ocular and nasal discharges, severe ulceration of the nasal mucosa and tracheitis and tachypnoea to varying degrees of severity. Parenteral administration of dexamethasone six months after challenge induced reactivation of virus shedding followed by a rise in humoral antibody titre irrespective of the original vaccination history.

Animals↗
PubMed1982

An investigation into the susceptibility of cattle to bovine leukosis virus following inoculation by various routes.

The effect of different routes of inoculation on the incubation period, as indicated by the detection of antibody and by the detection of bovine leukosis virus (BLV) in lymphocytes, were compared. None of the 12-month-old steers exposed to BLV by the oral route developed BLV infection. Intratracheal, subcutaneous and intradermal inoculations were found to be particularly effective in establishing BLV infection, which was detected three to four weeks after inoculation. In the majority of animals, serum antibody and virus were detected at the same time. One out of four in-oestrus heifers inoculated via the uterus with mixtures of BLV infected lymphocytes and semen became infected. It appears that there is an inhibitory factor in fresh semen that prevents BLV infection from becoming established. Viral antigen was detected earlier in BLV infected lymphocytes using the cocultivation method than by electron microscopy to demonstrate BLV particles in mitogen stimulated lymphocytes.

Animals↗
PubMed1982

Protection against bovine leukosis virus infection in sheep with the BL 20 bovine lymphoblastoid cell line.

The bovine lymphoblastoid BL 20 cell line derived from a case of sporadic bovine leukosis when inoculated into sheep did not induce an antibody response directed against bovine leukosis virus (BLV) structural proteins. Sheep were inoculated twice with the BL 20 cell line and then challenged with BLV infected lymphocytes. Three out of four sheep challenged four weeks after BL 20 inoculation did not develop BLV antibodies. Of the 12 sheep challenged later, three sheep did not develop BLV antibodies. BLV was isolated from all the seropositive animals and from none of the seronegative animals.

Animals↗
PubMed1981

Investigation of the possible role of the tuberculin intradermal test in the spread of enzootic bovine leukosis.

The single intradermal comparative test was used with both avian and bovine tuberculin. Three cattle infected with bovine leukosis virus (BLV) were used as a source of infection. BLV-positive and susceptible animals were tuberculin tested alternately. Fifteen susceptible calves and 15 susceptible sheep were tested. A further three valves and three sheep were used as controls; the needles of the tuberculin syringes were deliberately contaminated with blood from the BLV-infected cattle, before being used in the test. Whereas all three calves and the three sheep inoculated intradermally with contaminated needles developed BLV infections, all of the other 30 animals have remained serologically negative to BLV for 10 months. Transmission of BLV with needles contaminated with BLV-infected blood was prevented by wiping the needles with absorbent cotton wool.

Animals↗
PubMed1979

The demonstration of maedi/visna virus in sheep in Great Britain.

A virus indistinguishable from that causing maedi/visna has been isolated from a sheep flock in Great Britain. The virus was identified in cell cultures using immunofluorescent and electron microscopical techniques. The complement fixation test and the agar gel immunodiffusion test were used to assess the proportion of serological reactors within the flock. There has been no evidence of clinical disease in the flock into which foreign imports were introduced in the years prior to 1976.

Animals↗
PubMedDate not supplied

Animal and animal product importation and the assessment of risk from bluetongue and other ruminant orbiviruses.

Agriculture is an important component in the national economy of the United Kingdom and incursion of exotic disease would have severe effects on the United Kingdom domestic economy, causing both direct and indirect losses. The literature on bluetongue and other ruminant orbiviruses is reviewed in order to assess the risk of importing animal and animal products from countries with endemic infection. The literature is confusing, contradictory and incomplete and so cannot be used as a basis for designing practical import regulations with any certainty of eliminating risk. Contemporary methods used to prevent accidental introduction of bluetongue virus to uninfected areas, namely serological and virus isolation techniques, are not infallible. The phenomena of fetal infection, semen transmission and low or absent serological response in some cases mean that great vigilance is necessary.

Animals↗
PubMedDate not supplied

Rabbit haemorrhagic disease in the United Kingdom.

In April 1992, an investigation of sudden, increased mortality among adult rabbits on two premises in the south of England revealed clinical and pathological findings consistent with rabbit haemorrhagic disease. Virus particles morphologically resembling caliciviruses were detected in the livers of affected rabbits, and further studies confirmed the first recorded cases of rabbit haemorrhagic disease in the United Kingdom.

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