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Biomedical subjects

J F Evermann

Publications and source records attributed to J F Evermann.

At least 55 records · Page 3Linked to original sources
PubMed1991

Rapid antigenic-type replacement and DNA sequence evolution of canine parvovirus.

Analysis of canine parvovirus (CPV) isolates with a panel of monoclonal antibodies showed that after 1986, most viruses isolated from dogs in many parts of the United States differed antigenically from the viruses isolated prior to that date. The new antigenic type (designated CPV type 2b) has largely replaced the previous antigenic type (CPV type 2a) among virus isolates from the United States. This represents the second occurrence of a new antigenic type of this DNA virus since its emergence in 1978, as the original CPV type (CPV type 2) had previously been replaced between 1979 and 1981 by the CPV type 2a strain. DNA sequence comparisons showed that CPV types 2b and 2a differed by as few as two nonsynonymous (amino acid-changing) nucleotide substitutions in the VP-1 and VP-2 capsid protein genes. One mutation, resulting in an Asn-Asp difference at residue 426 in the VP-2 sequence, was shown by comparison with a neutralization-escape mutant selected with a non-CPV type 2b-reactive monoclonal antibody to determine the antigenic change. The mutation selected by that monoclonal antibody, a His-Tyr difference in VP-2 amino acid 222, was immediately adjacent to residue 426 in the three-dimensional structure of the CPV capsid. The CPV type 2b isolates are phylogenetically closely related to the CPV type 2a isolates and are probably derived from a common ancestor. Phylogenetic analysis showed a progressive evolution away from the original CPV type. This pattern of viral evolution appears most similar to that seen in some influenza A viruses.

Amino Acid Sequence↗
PubMed1990

Comparative features of retroviral infections of livestock.

Retroviral infections of livestock have become of increasing importance due to their usefulness as comparative models for human retroviral infections and their effects upon animal health and marketability of animals and animal products nationally and internationally. This paper presents a perspective on the retroviruses of economic concern in veterinary medicine with emphasis on the importance of understanding the modes of virus transmission and the species specificity of the viruses. The retroviruses reviewed include the oncovirus, bovine leukosis virus, and the lentiviruses, equine infectious anemia virus; maedi/visna virus, caprine arthritis-encephalitis virus and bovine visna-like virus. The comparative features amongst these animal retroviruses and those of humans must be recognized by the veterinary and medical professions since the similarities in virus replication and spread by blood transfer can provide important clues in controlling and perhaps preventing human retroviruses infections, such as the human immunodeficiency virus.

Animals↗
PubMed1990

Development of a rickettsia isolated from an aborted bovine fetus.

An obligate intracellular rickettsial organism isolated from an aborted bovine fetus was studied in bovine turbinate and mouse macrophage cell cultures with light and electron microscopy. Development of the organism was similar in both cell types. The organism replicated within cytoplasmic vacuoles in a developmental cycle that resembled that of both the ehrlichiae and chlamydiae. The inoculum contained only electron-dense forms, which infected cells within 2 h postinoculation by adhering to cell membranes at thickened areas that appeared to be coated pits and then being endocytosed. A striking feature occurred next as the organisms became surrounded by host cell mitochondria and, by light microscopy, appeared to have halos. During this intimate association with mitochondria, the electron-dense organisms changed into large reticulated forms that began to divide by binary fission. These large forms were often in direct contact with mitochondrial membranes. The organisms continued to divide by binary fission, and host cells contained large cytoplasmic inclusions of reticulated organisms. The reticulated organisms gradually changed into electron-dense forms that were released from degenerated host cells.

Abortion, Veterinary↗
PubMed1990

Isolation of a previously undescribed rickettsia from an aborted bovine fetus.

A previously undescribed obligate intracellular bacterium was isolated from an aborted bovine fetus. The organism was resistant to penicillin, replicated within cytoplasmic vacuoles, exhibited structural characteristics compatible with the rickettsias, and shared antigenic determinants with Cowdria ruminantium.

Abortion, Veterinary↗
PubMed1990

Prevalence and implications of feline coronavirus infections of captive and free-ranging cheetahs (Acinonyx jubatus).

The extent and progression of exposure to feline infectious peritonitis (FIP) virus in the cheetah, Acinonyx jubatus, was monitored by a world-wide serological survey with indirect fluorescent antibody titers to coronavirus. The indirect fluorescent antibody assay was validated by Western blots, which showed that all indirect fluorescent antibody-positive cheetah sera detected both domestic cat and cheetah coronavirus structural proteins. There was a poor correlation between indirect fluorescent antibody results and the presence of coronaviruslike particles in cheetah feces, suggesting that electron microscopic detection of shed particles may not be an easily interpreted diagnostic parameter for FIP disease. Low, but verifiable (by Western blots [immunoblots]) antibody titers against coronavirus were detected in eight free-ranging cheetahs from east Africa as well as from captive cheetahs throughout the world. Of 20 North American cheetah facilities screened, 9 had cheetahs with measurable antibodies to feline coronavirus. Five facilities showed patterns of an ongoing epizootic. Retrospective FIP virus titers of an FIP outbreak in a cheetah-breeding facility in Oregon were monitored over a 5-year period and are interpreted here in terms of clinical disease progression. During that outbreak the morbidity was over 90% and the mortality was 60%, far greater than any previously reported epizootic of FIP in any cat species. Age of infection was a significant risk factor in this epizootic, with infants (less than 3 months old) displaying significantly higher risk for mortality than subadults or adults. Based upon these observations, empirical generalizations are drawn which address epidemiologic concerns for cheetahs in the context of this lethal infectious agent.

Acinonyx↗
PubMed1989

Comparative features of a coronavirus isolated from a cheetah with feline infectious peritonitis.

A coronavirus which was isolated from a cheetah (Acinonyx jubatus) that succumbed to feline infectious peritonitis was characterized in vitro. The virus was determined to be highly cell-associated with Crandell feline kidney (CrFK) cells and was routinely maintained as a persistent infection (CrFK 83-4497). The cheetah coronavirus was compared with other members of the feline coronavirus group including the feline enteric coronavirus (FECV) 79-1683 and the feline infectious peritonitis viruses (FIPV), 79-1146, and UCD-1. The cheetah coronavirus was demonstrated to have a restricted host-cell range with limited cytopathic effect. Indirect immunofluorescence with antisera to FIPV UCD-1 revealed the concentration of viral antigens in the perinuclear region of cells infected with the cheetah coronavirus. Ultrastructural studies of the cheetah coronavirus indicated a limited number of immature viral particles within cytoplasmic vesicles and at the cell surface. This was in contrast to electron microscopy results of FECV 79-1683 and FIPV 79-1146, which had numerous mature virus particles within the cytoplasmic vesicles, as well as at the cell surface. The cheetah coronavirus was tentatively placed in the feline coronavirus family based upon its antigenic reactivity by immunofluorescence; however, the possibility that it represents a unique coronavirus of cheetahs should not be dismissed without further analyses at the host and genomic levels.

Acinonyx↗
PubMed1988

Epidemiologic survey of diarrhea in foals.

Epidemiologic and etiologic data about diarrhea in foals were collected under a planned prospective recording and monitoring study. The survey and monitoring procedures included a survey to obtain an overview of current horse management practices on participating farms, a daily health record survey to obtain information on mares and their foals, and collection of feces from 19 of 144 diarrheic foals and 10 age-matched nondiarrheic foals for electron microscopy, ELISA for rotavirus, and bacteriologic culture. Coronavirus was detected in the feces of diarrheic as well as clinically normal foals. Rotavirus was detected in the feces of diarrheic foals only. With regard to agents found in the feces, there was no significant (P less than 0.05) difference between diarrheic and nondiarrheic foals. Half of the 297 foals on which data were available developed diarrhea. Most foals that developed diarrhea lacked other clinical manifestations of disease. Basic cleanliness at foaling was associated with a lower percentage of foals developing diarrhea. Prophylactic use of antibiotics and vitamins in newborn foals was associated with a higher percentage of foals developing diarrhea. A higher percentage of foals born to visiting mares developed diarrhea, compared with foals born to resident mares.

Age Factors↗
PubMed1988

Experimental transmission of bovine leukosis virus by simulated rectal palpation.

Eight six-month-old Holstein male calves were experimentally inoculated by rectal palpation with whole blood from a donor seropositive to bovine leukosis virus. The inoculation consisted of the deposition of 2 ml of whole blood on a disposable obstetrical sleeve followed by a 30 second rectal palpation to simulate the process of pregnancy detection or artificial insemination. This procedure was repeated at weekly intervals for three consecutive weeks. All eight calves developed antibodies to bovine leukosis virus within five weeks after the initial palpation. The presence of the virus was demonstrated in the peripheral blood leucocytes of all eight calves at nine weeks. These results indicated that routine rectal palpation may be an effective mode of spread of bovine leukosis virus in susceptible cattle.

Animals↗
PubMed1988

Biological and pathological consequences of feline infectious peritonitis virus infection in the cheetah.

An epizootic of feline infectious peritonitis in a captive cheetah population during 1982-1983 served to focus attention on the susceptibility of the cheetah (Acinoyx jubatus) to infectious disease. Subsequent observations based upon seroepidemiological surveys and electron microscopy of fecal material verified that cheetahs were indeed capable of being infected by coronaviruses, which were antigenically related to coronaviruses affecting domestic cats, i.e. feline infectious peritonitis virus/feline enteric coronavirus. Coincident with the apparent increased susceptibility of the cheetah to infectious diseases, were observations that the cheetah was genetically unusual insofar as large amounts of enzyme-encoding loci were monomorphic, and that unrelated cheetahs were capable of accepting allogenic skin grafts. These data provided the basis for a hypothesis that the cheetah, through intensive inbreeding, had become more susceptible to viral infections as a result of genetic homogeneity.

Acinonyx↗
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

Passive immunity to bovine rotavirus infection associated with transfer of serum antibody into the intestinal lumen.

The effect of circulating passive antibody on immunity to bovine rotavirus infections in neonatal calves was investigated. In the first experiment, rotavirus antibody titers in the small intestinal lumina of 5- and 10-day-old calves with a wide range of serum rotavirus antibody titers were determined. Neutralizing antibody was present in the small intestinal lumina in titers that correlated with the calves' serum titers (r = +0.84, P less than 0.01). Immunoglobulin G1 was the predominant isotype of intestinal luminal rotavirus antibody. Calves not fed colostrum during the absorptive period lacked rotavirus antibody in circulation and in the intestinal lumen at 7 days of age, even when they were fed large volumes of colostrum with a high rotavirus antibody titer at 48 h after birth. Therefore, rotavirus antibody is not retained in the intestinal lumen for 5 days following a colostrum meal, and the luminal antibody in the 5- and 10-day-old seropositive calves were probably derived from circulating antibody. In a second experiment, calves were passively immunized by subcutaneous injection of colostral whey with a high immunoglobulin G1 rotavirus antibody titer and challenged with virulent bovine rotavirus 48 h later. The passively immunized calves were protected from rotavirus infection and diarrhea compared with calves with comparable serum immunoglobulin concentrations but with lower serum rotavirus with lower serum rotavirus antibody titers. The results of these experiments indicate that circulating immunoglobulin G1 antibody appears in the gastrointestinal tract of neonatal calves and that circulating rotavirus antibody can prevent infection and diarrhea after rotavirus challenge.

Animals↗
PubMed1988

Response of vaccinated and unvaccinated bighorn sheep (Ovis canadensis canadensis) to experimental respiratory syncytial virus challenge.

Five Rocky Mountain bighorn sheep (Ovis canadensis canadensis), approximately 5 mo old and without detectable antibody titers to respiratory syncytial virus (RSV), were assigned to two groups to study the effects of RSV challenge inoculation in vaccinated (n = 3) and unvaccinated (n = 2) bighorns. The three lambs vaccinated with a modified live bovine RSV vaccine developed a detectable antibody response to the vaccine. Vaccinated and unvaccinated lambs challenged with an ovine isolate of RSV developed increased levels of neutralizing antibody, but clinical signs of disease were not observed. Neutralizing antibody titers to RSV remained higher (2-4-fold) in vaccinated lambs over time when compared to unvaccinated lambs.

Animals↗