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Biomedical subjects

L E Carmichael

Publications and source records attributed to L E Carmichael.

At least 55 records · Page 3Linked to original sources
PubMed1984

Biological properties and dog response to a variant (M-) strain of Brucella canis.

Wild type (virulent) B. canis organisms are always rough and growth becomes extremely mucoid (M+) after several days of incubation, especially on media pH 7.2. The mucoid growth of virulent (M+) B. canis and the marked tendency for M+ bacteria, and extracted cell wall antigens, to aggregate at acid pH (pH less than 6.5) are markedly diminished in a less mucoid (M-) variant. The M+ and M- Brucella, and their extracted cell wall antigens, also differ in hydrophobic properties; the M+ organisms (and antigens) being the more hydrophobic. Immunoelectrophoresis and immunodiffusion analysis also revealed differences between the two strains. Prolonged survival (greater than 1 year) of B. canis in host tissues, with the production of abortions or epididymitis/orchitis is a principal expression of B. canis virulence. Pathogenicity studies in Beagles have indicated that the M- variant is reduced in virulence, since dogs given high doses of the M- strain by the subcutaneous or conjunctival/oral routes remained asymptomatic. Abortions did not occur in experimentally infected pregnant bitches and there was no epididymitis/orchitis in inoculated males. Nevertheless, M- bacteria persisted in the spleen, prostate tissue of some males, and in the lymph nodes for 3 to 9 postinoculation months. Serological responses of dogs to the M-organisms were generally weaker and less enduring than in dogs infected with the M+ Brucella. Sera from dogs infected with the M- strain generally reacted weakly in agglutination tests, especially when the antigen was B. ovis. The minimum infectious dose of M + B. canis was at least five times less than that of the M - Brucella (conjunctival or subcutaneous routes).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Antigenic structure and variation of canine parvovirus type-2, feline panleukopenia virus, and mink enteritis virus.

The antigenic structure and variation of canine parvovirus type-2 (CPV), feline panleukopenia virus (FPV), mink enteritis virus (MEV), and a closely related virus of raccoons (RPV) was investigated using a panel of 13 monoclonal antibodies (mAb) formed against CPV and 8 mAb formed against FPV. Each mAb both neutralized and inhibited the hemagglutination of the homologous virus. All mAb tested immunoprecipitated the two capsid proteins. Five mAb were specific for the CPV isolates and one reacted with the FPV, MEV, and RV isolates, but not the CPV. Another mAb reacted only with certain FPV and MEV isolates. The remaining 14 mAb reacted with most parvoviral isolates from the four animal species. Antigenic variation was observed both within and between the parvovirus isolates from each species. The 12 MEV isolates could be grouped into three antigenic types based on their reactivity with the panel of mAb. Antigenic variants of either CPV or FPV were readily selected with several mAb. Analysis of these variant viruses by direct serological tests and competition radioimmune assays between different mAb revealed that the capsid surface contained at least two determinants, each being comprised of many different but overlapping epitopes.

Animals↗
PubMed1983

Production of interferon by bovine peripheral blood monocytes infected with bovid herpesvirus 2.

The production of interferon by bovine peripheral blood leukocytes infected with bovid herpesvirus 2 (BHV-2) was investigated in preparation for studying mechanisms of resistance to BHV-2. It was found that bovine peripheral blood monocytes produced high levels of interferon in response to BHV-2 inoculated at a multiplicity of 1. Virus-induced interferon was not stable at pH 2, was destroyed at 56 degrees C or by incubation with trypsin and was active against both vesicular stomatitis virus and BHV-2. Interferon of high specific activity was produced by incubating monocytes for 5 h with BHV-2 in serum-containing medium, replacing the inoculum with serum-free medium for an additional 16 h, and concentrating the serum-free medium by dialysis against dry polyethylene glycol. Interferon concentrations of 40,000 units per mg of protein were readily attained.

Animals↗
PubMed1983

Canine viral enteritis.

Canine viral enteritis should be suspected in dogs with an acute onset of vomiting and diarrhea, especially in puppies and where several animals are affected simultaneously. Definitive diagnosis requires laboratory confirmation, most often detection of viral particles in the stool. No diagnostic test is entirely specific or absolutely sensitive, however, and laboratory findings should be weighed accordingly. Immunization is the key to successful control. Effective vaccines for canine parvovirus are available. Maternal antibody suppresses response to vaccination in young pups and is the major problem in the control of infection. Vaccines against canine rotavirus and coronavirus are not available. The need for such vaccines and the feasibility of their effective use have not yet been clearly demonstrated.

Animals↗
PubMed1983

Physicochemical transformation of milk components and release of foot-and-mouth disease virus.

Possible mechanisms for protective roles of milk components on foot-and-mouth disease virus present in the milk of infected cows were examined. Light scattering bands collected from Ficoll-sucrose gradient fractions of skim-milk contained membrane-limited structures but these were non-infectious for bovine kidney cells. Infectivity titres in buttermilk higher than those of the original cream or butter suggested association of virus with milk fat globules. Increased infectivity titres in skim-milk after treatment with SDS suggested release of virus particles from dissociated casein micelle subunits. Chelating agents, de-emulsifying agents and trypsin, which alter the structure of the individual milk components casein, lipid and milk fat globule membrane were without effect on infectivity titres.

Animals↗
PubMed1983

Use of modified live feline panleukopenia virus vaccine to immunize dogs against canine parvovirus.

Modified live feline panleukopenia virus (FPLV) vaccine protected dogs against canine parvovirus (CPV) infection. However, unlike the long-lived (greater than or equal to 20-month) immunity engendered by CPV infection, the response of dogs to living FPLV was variable. Doses of FPLV (snow leopard strain) in excess of 10(5.7) TCID50 were necessary for uniform immunization; smaller inocula resulted in decreased success rates. The duration of immunity, as measured by the persistence of hemagglutination-inhibiting antibody, was related to the magnitude of the initial response to vaccination; dogs with vigorous initial responses resisted oronasal CPV challenge exposure 6 months after vaccination, and hemagglutination-inhibiting antibodies persisted in such dogs for greater than 1 year. Limited replication of FPLV in dogs was demonstrated, but unlike CPV, the feline virus did not spread to contact dogs or cats. Adverse reactions were not associated with living FPLV vaccination, and FPLV did not interfere with simultaneous response to attenuated canine distemper virus.

Animals↗
PubMed1983

Histological and histochemical characterisation of mammary gland tissue of cows infected with foot-and-mouth disease by contact exposure.

Foot-and-mouth disease virus was observed to replicate in secretory epithelial cells of bovine mammary gland alveoli as a result of systemic infection initiated by exposure to infected animals. Viral antigens were demonstrated using fluorescent antibody and immunoperoxidase labelling techniques before the development of signs of clinical disease. In addition, labelled antigens were observed associated with cytoplasmic-like fragments in luminal membrane limited structures. Histologically, lesions of the alveolar secretory epithelium consisted of focal necrosis of these cells which eventually sloughed into the lumen.

Animals↗
PubMed1983

A modified live canine parvovirus vaccine. II. Immune response.

The safety and efficacy of an attenuated canine parvovirus (A-CPV) vaccine was evaluated in both experimental and in field dogs. After parenteral vaccination, seronegative dogs developed hemagglutination-inhibition (HI) antibody titers as early as postvaccination (PV) day 2. Maximal titers occurred within 1 week. Immunity was associated with the persistence of HI antibody titers (titers greater than 80) that endured at least 2 years. Immune dogs challenged with virulent CPV did not shed virus in their feces. The A-CPV vaccine did not cause illness alone or in combination with living canine distemper (CD) and canine adenovirus type-2 (CAV-2) vaccines, nor did it interfere with the immune response to the other viruses. A high rate (greater than 98%) of immunity was engendered in seronegative pups. In contrast, maternal antibody interfered with the active immune response to the A-CPV. More than 95% of the dogs with HI titers less than 10 responded to the vaccine, but only 50% responded when titers were approximately 20. No animal with a titer greater than 80 at the time of vaccination became actively immunized. Susceptibility to virulent CPV during that period when maternal antibody no longer protects against infection, but still prevents active immunization, is the principal cause of vaccinal failure in breeding kennels where CPV is present. Reduction, but not complete elimination, of CPV disease in large breeding kennels occurred within 1-2 months of instituting an A-CPV vaccination program.

Animals↗
PubMed1982

Maternally derived immunity to canine parvovirus infection: transfer, decline, and interference with vaccination.

Antibody to canine parvovirus (CPV) was transferred from an immune bitch to her pups through the placenta and colostrum. Colostral transfer accounted for approximately 90% of the maternally-derived CPV antibody. After suckling, pups and hemagglutination-inhibition titers that averaged 50% of their dam's titer. Maternally derived CPV antibody declined with a half-life of 9.7 days. Pups with hemagglutination-inhibition titers greater than or equal to 1:80 were immune to oronasal challenge with virulent CPV, but any detectable hemagglutination-inhibition antibody (titer greater than or equal to 1:10) interfered with active immunization by modified-liver feline panleukopenia virus, inactivated feline panleukopenia virus, or inactivated CPV vaccines.

Animals↗
PubMed1982

Antigenic relationships between canine parvovirus type 2, feline panleukopenia virus and mink enteritis virus using conventional antisera and monoclonal antibodies.

The antigenic relationships between three similar parvoviruses, canine parvovirus type 2 (CPV), feline panleukopenia virus (FPV) and mink enteritis virus (MEV) were investigated. Antisera against all 3 viruses and monoclonal antibodies (mAb) to CPV were prepared and the viruses compared using several serological methods. When conventional sera were used in the hemagglutination-inhibition and agar gel precipitin (AGP) tests there were no differences between the CPV viral isolates studied, but antigenic differences were revealed between the CPV isolates and the FPV or MEV. Of 16 mAb produced against CPV, six reacted only with the CPV. The other 10 mAb reacted with all three parvoviruses. Additionally, an antigenic difference was detected by AGP tests between one FPV isolate and the other FPV and MEV isolates. Including both conventional sera and mAb to CPV in a single AGP test with the CPV, MEV and FPV antigens permitted the comparison of results obtained with the different antibodies. The results reported revealed antigenic differences between CPV and FPV or MEV that were most clearly defined using mAb.

Animals↗
PubMed1982

Sensitivity of bovid herpesvirus 2 replication to temperatures found in the natural host.

Two isolates of bovid herpesvirus 2 replicated poorly in bovine testicular cells and fetal kidney cells at 39--40 degrees C, temperatures commonly observed in virus-infected cattle. High viral titers occurred in replicate cultures at 30--37 degrees C. Persistent viral infections were noted in cultures maintained at 40 degrees C. Interferon-like activity was not responsible for the high-temperature restriction since the level was not significantly different between virus-infected cultures incubated at 35 degrees or 40 degrees C. Spontaneous viral inactivation was only three times as rapid at 41 degrees as at 35 degrees C. Analysis of temperature shift experiments with respect to results of growth studies and electron microscopy indicated a temperature sensitive event late in replication. The sensitivity of bovid herpesvirus 2 replication to elevated temperature provides a possible explanation for the extensive viral growth and occasionally severe lesions which are limited exclusively to the skin of infected cattle.

Animals↗
PubMed1982

Improved rapid slide agglutination test for presumptive diagnosis of canine brucellosis.

A modified rapid slide agglutination test for the presumptive identification of Brucella canis infection in dogs has been developed. The method required mixing 0.1 ml of canine serum with 0.1 ml of 0.2 M 2-mercaptoethanol solution. Equal volumes (0.05 ml) of the treated serum and the B. canis plate antigen were mixed. Agglutination results were read within 2 min. Clinical studies showed 100% agreement between this method and the conventional 2-mercaptoethanol tube agglutination test. Excellent correlation was shown between cultural isolation and the modified rapid slide agglutination test, using sera from experimentally infected dogs.

Agglutination Tests↗
PubMed1982

Dog response to inactivated canine parvovirus and feline panleukopenia virus vaccines.

Inactivated canine parvovirus (CPV) and inactivated feline panleukopenia virus (FPV) vaccines were evaluated in dogs. Maximal serologic response occurred within 1-2 weeks after vaccination. Antibody titers then declined rapidly to low levels that persisted at least 20 weeks. Immunity to CPV, defined as complete resistance to infection, was correlated with serum antibody titer and did not persist longer than 6 weeks after vaccination with inactivated virus. However, protection against generalized infection was demonstrated 20 weeks after vaccination. In unvaccinated dogs, viremia and generalized infection occurred after oronasal challenge with virulent CPV. In contrast, viral replication was restricted to the intestinal tract and gut-associated lymphoid tissue of vaccinated dogs. Canine parvovirus was inactivated by formalin, beta-propiolactone (BPL), and binary ethylenimine (BEI) in serum-free media; inactivation kinetics were determined. Formalin resulted in a greater loss of viral HA than either BEI of BPL, and antigenicity was correspondingly reduced.

Animals↗
PubMed1982

Bovid herpesvirus 2 latency: failure to recover virus from central sensory nerve ganglia.

Latent bovid herpesvirus 2 was sought in sensory ganglia, epithelium and lymph nodes from cattle having antibodies against bovid herpes virus 2. Tissues from eight animals were maintained in vitro as explants for 49-72 days during which all expended media was tested for virus. Three animals were pretreated with corticosteroids prior to slaughter. Infectious bovine rhinotracheitis virus was recovered from one animal, but bovid herpesvirus 2 was not detected.

Animals↗
PubMed1982

Bovid herpesvirus 2: natural spread among breeding bulls.

Sera collected over a seven year period, together with detailed health and management records, were used in a retrospective study of Bovid herpesvirus 2 (BHV-2) spread within a large herd of breeding bulls. Virus spread rapidly throughout the bulls in one barn. Transfer of infected bulls to other barns was followed by further, although sporadic, spread of virus. Spread of BHV-2 from seropositive animals to susceptible bulls in close contact led to the conclusion that reactivation and transmission of latent virus had occurred. Semen from seropositive bulls did not transmit BHV-2 to seronegative calves that were purposefully inoculated by the intranasal or intravenous routes.

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