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D Chasey

Publications and source records attributed to D Chasey.

At least 19 recordsLinked to original sources
PubMed1997

Rabbit haemorrhagic disease: the new scourge of Oryctolagus cuniculus.

A new, widespread and important disease of rabbits, rabbit haemorrhagic disease (RHD), is concisely reviewed and discussed. RHD is an acute, infectious condition of adult rabbits and morbidity and mortality, after a relatively short incubation period, can be very high. The disease appears typically as a necrotizing hepatitis with associated haemorrhaging, and death occurs as a result of generalized organ dysfunction. RHD is caused by a calicivirus, antigenically related to a similar virus found in brown hares but distinct from other known caliciviruses, and is spread to susceptible rabbits by a number of routes and vectors. The disease is easily identified and can be effectively controlled in commercial and domestic rabbit populations by slaughter and vaccination regimes. The occurrence of pre-existing cross-reacting antibody in a proportion of rabbits unchallenged by the disease implies the presence of non-pathogenic strains of the virus. This antibody protects against disease on subsequent exposure to RHD. Uniquely, pre-existing antibody does not occur in rabbits in Australia where, after accidental release, the virus is currently spreading rapidly.

Animals↗
PubMed1996

Preliminary characterization of a non-haemagglutinating strain of rabbit haemorrhagic disease virus from the United Kingdom.

A variant strain of rabbit haemorrhagic disease virus, designated "Rainham', originally isolated from a small localized outbreak of the disease in southern England, has been further examined and compared with conventional reference strains. The virus originally failed to haemagglutinate in standard conditions at normal temperature and consistently lacked HA activity after two passages in experimental rabbits. It did haemagglutinate at 4 degrees C. It reacted with hyperimmune sera to normal isolates of RHDV from the UK and Italy, and showed no differential binding activity with a panel of monoclonal antibodies prepared from an Italian reference strain. The Rainham strain appears to be antigenically indistinguishable from other known isolates and this suggests that it may differ by only a few amino acid changes in its capsid protein sequence.

Animals↗
PubMed1995

Development of a diagnostic approach to the identification of rabbit haemorrhagic disease.

Haemagglutination and ELISA tests, and negative contrast electron microscopy, have been used to identify rabbit haemorrhagic disease virus in naturally occurring cases of the disease and in experimentally infected rabbits in the United Kingdom. Haemagglutination tests alone are not satisfactory for the diagnosis because non-haemagglutinating isolates of the virus, otherwise indistinguishable from others, have been found in some outbreaks. Haemagglutination inhibition tests have shown that a proportion of both commercial laboratory and wild rabbits in the UK are seropositive to the virus although they have not been associated with clinical disease. This observation, made previously in other parts of Europe, may indicate the longstanding circulation of a related but non-pathogenic strain of virus. Naturally occurring antibody appears to afford a high degree of protection against experimental challenge with virulent virus.

Animals↗
PubMed1994

Possible origin of rabbit haemorrhagic disease in the United Kingdom.

Rabbit haemorrhagic disease was reported for the first time in the United Kingdom in 1992, and there followed four further small localised outbreaks, all in the south of England. Investigation has revealed no definitive mechanism for the introduction of the disease but it is considered that it probably originated from the near continent. The possibility of the transmission of the virus across the Channel by aerosol, birds and south coast ferry traffic is discussed, particularly with respect to the 1993 outbreaks of the disease in Kent and East Sussex. There may be implications for infection of wild rabbits, although preliminary investigation has shown no direct evidence of the disease in them.

Animals↗
PubMed1994

European brown hare syndrome in England.

The livers from 50 brown hares (Lepus europaeus) were examined by electron microscopy for calicivirus-like particles typical of the virus of European brown hare syndrome (EBHS). The virus was visible in 23 of the livers which included four taken from hares which died in 1982 and 1985 and which had been stored at -20 degrees C. The clinical histories, post mortem and other findings associated with these 23 hares were similar to those described in cases of European brown hare syndrome in other European countries. The findings were compared with those associated with viral haemorrhagic disease (VHD) of rabbits which, although it did not occur in the United Kingdom until 1992, is also caused by a calicivirus believed to be related to EBHS virus. The finding of the virus in hares which died from the disease in 1982 is the earliest recorded isolation of the organism and predates the description of VHD virus and VHD in China in 1984. A retrospective review of post mortem reports revealed cases of disease between 1976 and 1977 which may have been due to EBHS and it is considered that the disease has occurred sporadically in England for several years. The results from suspected and confirmed cases of EBHS in England between 1976 and 1990 are reported and the epidemiology and emergence of the disease is considered.

Animals↗
PubMed1992

European brown hare syndrome in the U.K.; a calicivirus related to but distinct from that of viral haemorrhagic disease in rabbits.

The virus recovered from cases of European brown hare syndrome in the U.K. contains one major capsid protein of approximately 60 k molecular weight and morphologically resembles known caliciviruses. It has been compared with a European isolate of rabbit haemorrhagic disease calicivirus and, although it shows some antigenic similarity, it is not identical. In transmission and protection studies the virus from U.K. hares failed to produce disease in rabbits and did not effectively protect against subsequent challenge with the rabbit calicivirus.

Animals↗
PubMed1992

Haemorrhagic disease of lagomorphs: evidence for a calicivirus.

Studies on the aetiological agents of rabbit haemorrhagic disease (RHD) and European brown hare syndrome show that the viruses responsible for these infections can be placed in the family Caliciviridae. Established members of this group are vesicular exanthema virus (prototype), San Miguel sea lion virus and feline calcivirus. The human hepatitis E virus and the Norwalk agent may soon be included. The RHD virus genome consists of a positive stranded RNA molecule composed of 7437 nucleotides. A major subgenomic RNA of 2.2 kb, colinear with the 3' end of the genomic RNA, can also be recovered from infected liver tissue, and both RNAs are enclosed within viral capsids formed by a single major protein of approximately 60 kDa. Electron microscopic examination of organ suspensions from diseased animals shows two types of particle; 35-40 nm complete virions have the regularly arranged cup-shaped depressions typical of calcivirus morphology, and 23-25 nm smooth particles resulting from degradation of the outer surface structures of the complete virions.

Animals↗
PubMed1992

Development of monoclonal antibody ELISA for simultaneous detection of bovine coronavirus, rotavirus serogroup A, and Escherichia coli K99 antigen in feces of calves.

A rapid ELISA was developed for simultaneous detection of bovine coronavirus (BCV), rotavirus (RV) serogroup A, and Escherichia coli K99 antigen in feces of calves. A mixture of 3 monoclonal antibodies specific for BCV, RV, or K99 was used successfully to capture the antigens; the same antibodies labeled with peroxidase were used to detect BCV, RV, or K99. The triple ELISA was compared with standard reference diagnostic methods by examining feces from experimentally and naturally infected and healthy calves. All the components of the test were highly specific (greater than 90%) and sensitive (BCV, 77%; K99, 93%; RV, 100%) when used in a format requiring short incubation steps at 20 C and visual recording of results.

Animals↗
PubMed1990

Detection of a novel fimbrial structure on the surface of Salmonella enteritidis by using a monoclonal antibody.

A fimbrialike structure expressed on the surface of Salmonella enteritidis was identified by using a monoclonal antibody (69/25) produced against intact S. enteritidis cells. Fimbriae were less than 5 nm in diameter and carried a protein consisting of subunits with a molecular weight of 14,300. No hemagglutinating activity associated with the fimbriae was detected. An epitope on the fimbrial antigen identified by monoclonal antibody 69/25 was expressed by all 58 S. enteritidis strains, 12 of 36 S. dublin strains, and a single strain of S. moscow examined. None of 169 other isolates tested from 17 salmonella serogroups expressed this epitope.

Antibodies, Monoclonal↗
PubMed1989

Atypical rotavirus and villous epithelial cell syncytia in piglets.

Histopathological examination of small and large intestine from piglets with enteritis has shown the presence of epithelial multinucleate syncytia. Syncytia were associated with a specific type of atypical rotavirus infection, determined by electron microscopy and polyacrylamide gel electrophoresis analysis of viral RNA. The observations are consistent with similar previously described natural or experimental infections in other animals.

Animals↗
PubMed1988

Some observations on the semen of bulls persistently infected with bovine virus diarrhoea virus.

As a result of screening procedures employed for animals entering the AI service, two bulls were identified as being persistently infected with bovine virus diarrhoea virus by isolation of the virus from blood. Semen was collected on two occasions from these bulls; its quality as measured by density and motility was poor. Gross abnormalities of the sperm head, termed 'collapsed' heads, were seen in 28 to 45 per cent of sperm from one bull and in 1 per cent of sperm from the other. The collapsed heads were small and the whole head or its anterior part had the appearance of a dried pea. Electron microscopy showed the defect to consist of convoluted nuclear material with membrane-bound vacuoles and invaginations containing membranous debris and lamellar structures. In the 'high incidence' bull there was a corresponding increase in enlarged sperm heads. The 'low incidence' bull had sperm with heads of similar mean size to sperm from control bulls but with an increased variance. The semen was diluted in a lactose diluent, frozen and stored in liquid nitrogen. The distribution of viral antigen was determined and virus was isolated from several fractions of the semen, both before and after processing and cryopreservation. In one animal raw semen failed to yield virus but virus was recovered after processing, suggesting that raw semen may not be suitable for the efficient detection of the virus.

Animals↗
PubMed1988

Morphological defects of the acrosome in boar spermatozoa.

Morphological examination of semen from 17 boars of five breeds showed the presence of acrosome defects in 11 boars from four breeds. Two distinct types were seen; 'knobbed' sperm (type 1), of which two forms were found to be present by electron microscopy, and an uneven swellling of part of the acrosome (type 2) whose contents consisted of cytoplasmic and membrane-like material. The incidence of 'knobbed' sperm ranged from 0.2 to 6.3 per cent. Type 2 abnormalities were seen in only two boars, at 0.66 and 1.33 per cent.

Acrosome↗
PubMed1987

A comparison of three rapid diagnostic methods for the detection of rotavirus infection in calves.

Three techniques for the detection of rotavirus in faecal samples from calves with neonatal gastroenteritis were compared. A preliminary study indicated that reverse passive haemagglutination (RPHA) was at least as sensitive as the enzyme-linked immunosorbent assay (ELISA). These two immunoassays were compared with the detection of viral RNA by polyacrylamide gel electrophoresis (PAGE) on 209 field samples. Of the 77 samples in which at least one test gave a positive result, 69 were positive by both RPHA and PAGE, but only 49 were also positive by ELISA, indicating a lower sensitivity for the latter test. The overall agreement between RPHA and PAGE was 96%. The reasons for the discrepancies between the tests are discussed.

Animals↗
PubMed1986

A new type of atypical rotavirus in pigs.

Two independent isolates of an unusual type of rotavirus were obtained from over 900 faecal samples obtained from piglets with diarrhoea. Genome profiles, containing eleven segments, were not characteristic of group A electropherotypes and corresponded to an atypical virus. The profiles were, however, distinct from those of other previously described atypical porcine rotaviruses. Serological comparisons showed that the two isolates were related, but unrelated to other known groups of porcine rotavirus. The new isolates were passaged in gnotobiotic piglets in which they caused mild clinical signs of enteritis. A survey of porcine sera from the United Kingdom indicated a widespread distribution of antibody to this virus in pigs aged 10 weeks and over.

Animals↗