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Biomedical subjects

L E Carmichael

Publications and source records attributed to L E Carmichael.

At least 37 records · Page 2Linked to original sources
PubMed1992

Fatal disease in nursing puppies associated with minute virus of canines.

Thirteen cases of a previously undescribed parvoviral infection affecting puppies ranging in age from 5 to 21 days is described. The cases were originally thought to represent an unusual pathologic manifestation of canine parvovirus-2 (CPV-2) infection. However, failure to confirm CPV-2 infection in any of the cases suggested a different parvovirus was involved. Minute virus of canines (MVC) was subsequently isolated from a case by using the Walter Reed Canine Cell Line, the only cell line which will support the growth of MVC. The pathologic and virologic findings for these 13 cases are described in this report.

Animals↗
PubMed1991

Characterization of BPV-like DNA in equine sarcoids.

The DNA from equine sarcoid samples from New York State and Switzerland was isolated and probed with bovine papillomavirus type 1 (BPV-1) to determine if BPV genomes were present. Twelve of 13 sarcoids from New York State and 17/20 sarcoids from Switzerland contained DNA that hybridized to the BPV-1 probe. Restriction enzyme analysis of the positive samples demonstrated restriction fragment profiles characteristic of BPV-1 in 22 sarcoids and restriction fragment profiles characteristic of bovine papillomavirus type 2 (BPV-2) in 7 sarcoids. In addition, three tissues histologically diagnosed as pyogranulomatous dermatitis, fibropapilloma, and fibrosarcoma contained BPV-like DNA. Tissues with BPV-1-like and BPV-2-like DNA contained an average of 285.7 (21 to 808) and 125.8 (2 to 762) BPV-like genomes per cell, respectively. Minor differences in the restriction fragment profiles of the BPV-like DNA and evidence for partial BPV-like genomes were found in some sarcoids. BPV-like DNA was not detected in lymphocyte DNA from sarcoid-affected horses. These results confirm previous observations and support the hypothesis that bovine papillomavirus, or a very similar virus, is linked to the cause of equine sarcoid.

Animals↗
PubMed1991

Pathogenicity of minute virus of canines (MVC) for the canine fetus.

Minute Virus of Canines (MVC) was shown to cause transplacental infections with embryo resorptions, especially in dams given parenteral inoculations prior to gestational day 30. Responses to oral-nasal inocula were inconsistent. Direct exposures of embryos or fetuses to MVC via the amniotic sac, however, resulted in their deaths after an incubation period of approximately 2 weeks. Virus was prominent in fetal lung and small intestinal villi, but it could not be demonstrated in fetal or uterine tissues greater than 2 weeks after the estimated time of embryonic/fetal death. With 1 exception, dams inoculated during the last trimester of pregnancy gave birth to normal pups; some pups had developed active immune responses. The exceptional dam whelped dead or dying pups with anasarca or myocarditis. Antibody levels to MVC were generally higher in dams with infected fetuses than in bitches with normal pups at term. Failures to isolate virus, or demonstrate viral antigens in tissues by immunostaining, other than near the time of embryo/fetal death, indicate the need for more sensitive viral detection methods.

Animals↗
PubMed1989

Characterization of Brucella canis protein antigens and polypeptide antibody responses of infected dogs.

The cytoplasmic protein antigens (CPAg) of Brucella canis were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and analysis of 35S-labeled polypeptides. Approximate molecular weights of the immunoreactive polypeptides were determined by migration patterns of the immunoprecipitated polypeptides after SDS-PAGE or Western immunoblotting of sera collected at various times after experimental infection of dogs. Polypeptides were specifically precipitated by sera of infected dogs, but not from the sera of normal or false-positive (seropositive, non-infected) animals. During the initial month after infection, proteins with molecular weight masses (MW) of approximately 18, 22, 31, 42 and 54 kDa were commonly recognized. A 20-kDa polypeptide was first recognized at 8-10 weeks after infection, but it was detected inconsistently after 6 months. Additional polypeptides detected from 2 to 12 months post-infection had MW of 22, 66-68 and, less regularly, 42, 60, 82, 100 and greater than 200 kDa. The polypeptides most consistently recognized in sera from B. canis-infected dogs had MW of 18, 22 and 68 kDa.

Animals↗
PubMed1988

Characterization of a nonhemagglutinating mutant of canine parvovirus.

A nonhemagglutinating mutant of a 1978 isolate of canine parvovirus (CPV) was derived after repeated passages in the NLFK feline kidney cell line. The mutant CPV was antigenically indistinguishable from wild-type virus when tested with 82 monoclonal antibodies, and it replicated in cat and dog cell lines in culture. Sequences of the VP-1 and VP-2 genes revealed two nucleotide and two predicted amino acid sequence differences at 77 and 88 genome map units in the mutant compared to hemagglutinating viruses. One or both of those two mutations must determine the difference in the ability of the virus to agglutinate erythrocytes.

Amino Acid Sequence↗
PubMed1988

Canine host range and a specific epitope map along with variant sequences in the capsid protein gene of canine parvovirus and related feline, mink, and raccoon parvoviruses.

Canine parvovirus (CPV) is a recently recognized pathogen of dogs that is similar to the long-recognized feline, mink, and raccoon parvoviruses. Relationships between the viruses determined from DNA sequences of the capsid protein genes of 10 virus isolates showed the CPV isolates to be closely related to the other viruses, although comprising a distinct group. No immediate ancestor of CPV was observed amongst the mink, cat, or raccoon viruses examined. Three different directly repeated sequences were present within the noncoding region downstream from the capsid protein genes. Analysis of recombinants between CPV and feline panleukopenia virus at restriction sites within the capsid protein genes mapped a CPV-specific neutralization epitope on the virus capsid, differences in the pH dependence of hemagglutination, and part of the determinant of canine host range between 59 and 64 genome map units (m.u.). Those differences were therefore the result of up to three nucleotide or predicted amino acid sequence differences in that region. A second region between 64 and 73 m.u., which may affect the viability of certain recombinant viruses, contained four nucleotide differences, one of which was a coding change.

Animals↗
PubMed1988

The global spread and replacement of canine parvovirus strains.

Canine parvovirus type 2 (CPV-2) became widespread during 1978 and was reported in many countries during 1978 and 1979. Earlier studies showed that CPV-2 was replaced in the U.S.A. around 1980 by an antigenically and genetically variant virus (CPV-2a). Here we show that CPV-2 was present in the U.S.A., Japan, Belgium and Australia prior to 1980, but that between 1979 and 1982 CPV-2 was replaced by CPV-2a in all of those countries as well as in France and Denmark. Examination of sera collected between 1979 and 1984 from wild coyotes (Canis latrans) in the U.S.A. by an agar gel precipitin assay indicated that the coyotes were originally infected by CPV-2, but that after 1980 the juvenile coyotes were being infected with CPV-2a. The natural global replacement of CPV-2 by CPV-2a over a period of 2 to 3 years indicates that CPV-2a has a strong epidemiological advantage over CPV-2, although the mechanism involved remains to be defined.

Animals↗
PubMed1988

Characterization of minute virus of canines (MVC) and its pathogenicity for pups.

Minute virus of canines (MVC, canine parvovirus-1), originally isolated in 1970 from the feces of normal dogs, was compared with canine parvovirus type-2 (CPV-2). The two viruses, which differ in their host cell ranges and spectra of hemagglutination, also were found distinct in their antigenic and genomic properties. We demonstrated that the MVC replicates in dogs and is capable of producing pathologic changes that were most prominent in oronasally-exposed neonatal pups. Macroscopic and microscopic lesions were most prominent in the thymus and lymph nodes; minor changes were found in the duodenal crypts. The MVC strain used had been passaged 13 times in cell cultures and it may not represent the true virulence of naturally occurring virus.

Animals↗
PubMed1988

Transmission of Brucella canis by contact exposure.

Transmission studies demonstrated that canine brucellosis can spread from infected to susceptible males maintained in close contact after 4 to 6 months of cohabitation. Spread by males occurred after epididymitis was observed in the infected dogs. Transmission via contaminated urine was suspected, but not proved. The bladder urine of infected males, probably contaminated with seminal fluid, contained higher numbers of B. canis organisms than did that of female dogs. Highest concentrations of bacteria in urine were found between postinfection weeks 8 and 12. Infected females transmitted the infection to contact females after 5 months. Immature females or males infected with B. canis did not transmit brucellosis until after an estrus or a mating was observed--about post-contact months 10-12.

Animals↗
PubMed1987

A rapid slide agglutination test for the serodiagnosis of Brucella canis infection that employs a variant (M-) organism as antigen.

An improved antigen is described for use in the serodiagnosis of canine brucellosis. The novel antigen employs a less mucoid (M-) variant of B. canis. The replacement of Brucella ovis with B. canis (M-) cells as antigen in slide agglutination tests would increase accuracy by reducing the rate of false positive results from ca. 50% to ca. 10%. Rose bengal stained B. canis (M-) cells are slightly more sensitive than the commercially available Brucella ovis as slide test antigens. Both test procedures require brief (less than 1 min) reaction with 2-mercaptoethanol in order to reduce the rate of false positive reactions.

Agglutination Tests↗
PubMed1986

Characterization and recombination mapping of an antigenic and host range mutation of canine parvovirus.

A mutant of canine parvovirus (CPV) was derived after culture of a highly passaged isolate of CPV in the NLFK feline cell line. The virus (CPV-102/10) differed from the parental strain in its antigenic type when tested with a panel of neutralizing monoclonal antibodies, and in its relative ability to replicate in a dog cell line or in dogs. The mutant formed little replicative form DNA in the canine cells. Five single recombinants and two double recombinants between CPV-102/10 and a wild type CPV were constructed by digesting purified viral replicative form DNA with restriction enzymes, ligating the separated ends from the different strains, and examining the viruses isolated after transfecting the DNA into cell cultures. Analysis of the recombinant viruses showed that the mutation(s) determining both the antigenic and host range differences mapped between 64 and 73 map units in the genome, within the capsid protein gene. Sequencing the DNA from that region revealed differences of two adjacent amino acids, both resulting in nonconservative differences in the predicted amino acid sequences of the viruses. These results show that the ability of CPV to infect dogs or their cultured cells is determined, at least in part, by the conformation of the surface of the virus capsid.

Amino Acid Sequence↗
PubMed1985

Natural variation of canine parvovirus.

Canine parvovirus was first recognized during 1978. Analysis of isolates collected since its emergence revealed that viruses circulating after 1980 were antigenically different from earlier isolates. Monoclonal antibodies clearly distinguished the two strains, some being specific for either the old or the new viruses. Restriction enzyme analysis of viral DNA's showed that the post-1980 viruses were similar to earlier isolates, but some restriction site differences were present in the new strain. These results suggest that the canine parvoviruses infecting dogs in the seven areas of the United States that were sampled derive from a variant virus that replaced the original strain during 1980.

Animals↗
PubMed1984

The effect of temperature on production and function of bovine interferons.

Subnormal temperatures were found to depress the production of interferon by bovid herpesvirus 2 (BHV-2)-infected bovine testicular cells, bovine peripheral blood leukocytes, and bovine monocytes, as well as by BHV-2 antigen-stimulated immune peripheral blood leukocytes. Interferon titers generated at 30 degrees C were approximately 10 percent of those at 40 degrees C. Also, subnormal temperatures depressed interferon function. Bovine testicular cells treated at 40 degrees C for 24 hours with high concentrations of BHV-2-induced bovine monocyte interferon or BHV-2 antigen-stimulated immune peripheral blood leukocyte interferon, and then infected with BHV-2 and retreated with interferon at 40 degrees C, had little or no viral growth or cytopathic effect after 72 hours. Cultures without interferon, or those treated with the same amount of interferon at 30 degrees C, had significantly more cytopathic effect and had viral titers up to 10(7) TCID50 higher than cultures at 40 degrees C. Earlier in vitro studies done without exogenous interferon showed that BHV-2 replicated to high titers at 30 degrees but not at 40 degrees C. Thus, at low temperatures (30 degrees C) in vitro, BHV-2 induced little interferon, was not highly suppressed by interferon, and replicated to high titers. At higher temperatures (40 degrees C), BHV-2 replication induced high interferon levels, was strongly suppressed by interferon, and replicated poorly. This may help explain the restriction of BHV-2 lesions to skin despite the presence of virus in both skin and internal organs in infected cattle.

Animals↗
PubMed1984

Local tissue temperature: a critical factor in the pathogenesis of bovid herpesvirus 2.

The effect of local tissue temperature on bovid herpesvirus 2 lesions in bovine skin was studied. Two areas of thoracic skin were multiply inoculated with virus and maintained at different temperatures; one above and the other below the rectal temperature of the animal. An entire inoculation site was removed daily from each area and subjected to virus, viral antigen, and interferon titrations and both light and electron microscopic examinations. Lesions in cold skin appeared sooner after inoculation, were larger and deeper, contained more infectious virus, viral antigen, and interferon, and lasted longer than lesions in hot skin. Differences in viral titers greater than 10(9) 50% tissue culture infective doses per gram were measured on postinfection days 5 to 9. These studies have demonstrated for the first time that temperature effects on viral pathogenesis may operate at the local level rather than by systemic modification of immune responses. The results also suggest that despite the presence of virus in internal organs of bovid herpesvirus 2-infected cattle and the ability of bovid herpesvirus 2 to replicate to very high titers in these tissues in vitro, only the skin is cool enough to permit substantial viral replication and dermal lesions in vivo. The observed restriction of bovid herpesvirus 2 skin lesions to the udder and teats of cattle and the restriction of outbreaks of disease to months when the temperature is declining may also be reflections of this temperature sensitivity.

Animals↗
PubMed1984

Characterization of antigenic variation among mink enteritis virus isolates.

Three antigenic forms of natural field isolates of mink enteritis virus were revealed with a panel of monoclonal antibodies generated against the closely studied feline panleukopenia virus and canine parvovirus-2 virus. Two types (types 2 and 3) were shown to be closely related by agar-gel precipitin tests and by restriction enzyme mapping. However, types 2 and 3 differed from the type 1 isolates in the same tests. In cross-protection studies, inactivated viral vaccines made from any one of the 3 variant types of mink enteritis virus protected mink against challenge exposure by the homologous, as well as the heterologous, antigenic types.

Animals↗
PubMed1984

Response of puppies to canine-origin parvovirus vaccines.

Pups 9-18 1/2 weeks old were given a single dose of 1 of 4 commercial, live, canine-origin parvovirus vaccines. All 4 vaccines evoked high levels of antibody in seronegative pups, but variable response in those with low levels of maternally derived antibodies. Vaccinal virus spread to unvaccinated contact controls and elicited essentially equivalent titers. No clinical signs of parvovirus infection were observed in vaccinates or controls.

Animals↗
PubMed1984

Problems in the serodiagnosis of canine brucellosis: dog responses to cell wall and internal antigens of Brucella canis.

Three procedures are commonly used for the serodiagnosis of B. canis infection: 1) The rapid slide agglutination test (RSAT), 2) the tube agglutination test (TAT), and 3) the modified 2-mercaptoethanol tube agglutination test (2ME-TAT). Hemocultures are always essential for diagnosis. The RSAT was developed to provide a presumptive diagnosis rapidly. It has been found accurate in identifying non-infected dogs; however false positive reactions are common due to shared determinants between the surface antigens of B. canis and certain other gram-negative bacteria. The RSAT has recently been modified to include brief reaction of test sera with 2ME (0.2M) prior to adding test antigen. The modification has improved specificity, but it has not eliminated false positive reactions. The TAT and 2ME-TAT are widely used. Although there is good agreement between tests, both suffer from lack of specificity but are valuable in kennels where B. canis has been identified by blood cultures. Agarose gel immunodiffusion (AGID) tests using extracted (SDC or hot PBS) cell wall antigenic complexes reveal precipitins in the sera of infected dogs usually 8 to 12 weeks postinfection (PI) that may persist 5 years. The antigenic complexes consist of at least 3 antigens; one (antigen '2R') appears to possess high B. canis specificity. Sera from noninfected dogs also may react nonspecifically in AGID tests that employ crude SDC or PBS antigenic extracts leading to 'false positive' interpretations. Cytoplasmic antigens gave up to four precipitin lines with sera from B. canis infected dogs. The antigens (protein or glycoprotein) were present in both S and R Brucella cells, but not in other gram-negative organisms examined. AGID tests that employed cytoplasmic antigens revealed precipitins against one or more (usually 2-3) antigens from PI months 4 through 64. In some dogs, precipitins were present 12 months after the bacteremia had ceased, a time when other tests were diagnostically insignificant, or equivocal. No 'false positive' field sera reached with the cytoplasmic antigens.

Animals↗