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Biomedical subjects

J E Pearson

Publications and source records attributed to J E Pearson.

At least 19 recordsLinked to original sources
PubMed1995

Comparison of polymerase chain reaction and virus isolation for detection of epizootic hemorrhagic disease virus in clinical samples from naturally infected deer.

We compared our recently reported reverse transcriptase polymerase chain reaction (PCR)-based assay for detection of epizootic hemorrhagic disease virus (EHDV) in clinical samples with different virus isolation (VI) procedures. Thirty-six blood samples and 1 spleen sample from deer were assessed by the EHDV PCR assay and VI in baby hamster kidney (BHK)-21 cells and embryonated chicken eggs (ECE). The EHDV PCR assay detected EHDV RNA from 6 blood samples obtained from deer during 1988-1989 outbreaks of epizootic hemorrhagic disease and from the spleen and blood samples of a deer with clinical hemorrhagic disease in 1992. The 6 blood samples from the 1988-1989 outbreaks and the spleen sample from the 1992 case were VI positive on BHK-21 cell culture. The blood from the same deer with the PCR- and VI-positive spleen was VI negative in BHK-21 cells and ECE. All EHDV isolates were identified as EHDV serotype 2 by a plaque inhibition test. The results of this study indicate that the sensitivity of the previously described EHDV PCR assay is comparable to or greater than that of the VI method in BHK-21 cell culture or ECE. The EHDV PCR assays could provide a superior diagnostic alternative to the current cumbersome and time-consuming VI procedures.

Animals↗
PubMed1994

Diagnosis of eastern equine encephalomyelitis virus infection in horses by immunoglobulin M and G capture enzyme-linked immunosorbent assay.

Immunoglobulin M (IgM) and G (IgG) capture enzyme-linked immunosorbent assays (ELISAs) were used as possible adjuncts to hemagglutination inhibition (HI) and virus neutralization (VN) tests to differentiate between reaction to recent exposure to eastern equine encephalomyelitis (EEE) virus and those due to prior vaccination. Serum samples were evaluated by the IgM-capture ELISA, and the results were compared with those of HI and VN tests. Of 381 serum samples, 51% (195 samples) were positive by HI test (> or = 1:40) and 54% (205 samples) were positive by VN test (> or = 1:10), but only 35% (132 samples) were positive by IgM-capture ELISA (> or = 1:100). With only a few exceptions, the sera with IgG ELISA titers had a VN titer of > or = 1:100. When EEE virus isolation and serology were compared, the EEE cases were divided into three categories: 1) peracute cases--the serum was negative for EEE IgM and IgG by the ELISA, negative for VN antibody, but HI antibody positive; 2) acute cases--IgM and HI antibody positive but negative for IgG and VN antibody; and 3) transitional cases--positive for IgM and IgG antibodies, HI titers of 1:40-1:160, and VN titers of > or = 1:100. IgM antibodies of EEE virus were monospecific and did not cross-react with western or Venezuelan equine encephalomyelitis viral antigens by the ELISA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Hog cholera diagnostic techniques.

Clinical signs and lesions can sometimes provide the basis for a presumptive diagnosis of hog cholera (HC). However, an accurate diagnosis requires laboratory testing. The usual procedure for the detection of viral antigen is the examination of cryostat sections stained with fluorescein-conjugated HC antiserum. A more definitive technique is isolation of the virus in PK-15 cell cultures and identification of the viral antigen in cells using an HC fluorescent antibody conjugate. As bovine viral diarrhea (BVD) virus will cross-react with HC virus, isolation must be confirmed by the comparison of BVD and HC staining or, preferably, by the use of monoclonal antibodies that can differentiate between HC and BVD viruses. Hog cholera surveillance must rely on serology. The fluorescent antibody virus neutralization (FAVN) test is the classical technique, and HC and BVD antibody can usually be differentiated if HC-positive serum samples are tested against both viruses. Recently the enzyme-linked immunosorbent assay (ELISA) and peroxidase-labeled antibody tests have become the commonly used techniques.

Animals↗
PubMed1992

Competitive ELISA for serodiagnosis of bluetongue: evaluation of group-specific monoclonal antibodies and expressed VP7 antigen.

The performance of 2 competitive enzyme-linked immunosorbent assays (C-ELISA) was compared with the reference C-ELISA I for the detection of antibodies to bluetongue virus (BTV). One of the assays (C-ELISA II) used a group-specific monoclonal antibody (MAb) to BTV, obtained from the American Type Culture Collection (8A3B-6) and tissue culture (TC)-derived BTV antigen (Ag), and the other assay (C-ELISA III) used BTV core protein VP7 (expressed in yeast) and the reference MAb (Pirbright Laboratory, 3-17-A3). Test sera were obtained by sequential blood samples from 22 calves, each inoculated with a different serotype (T) of BTV (South African [SA] T-1-T-16 and T-18-T-20 and USA T-11, T-13, and T-17). Sera were also obtained from 4 calves and 4 sheep inoculated with USA BTV T-10 and from several groups of calves exposed to single or multiple doses of epizootic hemorrhagic disease virus (EHDV) T-1-T-4 grown in TC (BHK-21) or suckling mouse brain (SMB). A total of 618 bovine and ovine field sera collected from BT-free and BT-endemic areas were also tested. The C-ELISA III was more sensitive than the C-ELISA II in the detection of anti-BTV antibody in sera from cattle and sheep early after infection with BTV. Seroconversion was demonstrated by the 3 C-ELISAs in all animals inoculated with BTV by 20 days postinfection (DPI), except in calves that received SA T-3 or USA T-13, which became positive at 40 DPI.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Precipitating antibodies to epizootic hemorrhagic disease and bluetongue viruses in white-tailed deer in the southeastern United States.

From 1981 to 1989, sera were collected from 3,077 white-tailed deer (Odocoileus virginianus) in Georgia and from 1,749 deer from 12 additional states in the southeastern United States. In Georgia, prevalence of precipitating antibodies to epizootic hemorrhagic disease virus (EHDV) and bluetongue virus (BTV), as determined by agar gel immunodiffusion tests, was dependent on physiographic region, age, and year. Overall prevalence of antibodies to EHDV and/or BTV was 11, 33, 48, and 14% for the Mountain, Piedmont, Coastal Plain, and Barrier Island regions, respectively. Results suggested varying patterns of EHDV and BTV activity throughout the state. Serologic results from other southeastern states were consistent with the Georgia sample; prevalence estimates (EHDV and/or BTV) for corresponding physiographic regions deviated by less than 10%. Over this larger geographical area, antibody prevalence in deer appeared to increase with decreasing latitude.

Age Factors↗
PubMed1991

Antibodies to bluetongue and epizootic hemorrhagic disease viruses in a barrier island white-tailed deer population.

From 1981 through 1989, serum samples from 855 white-tailed deer (Odocoileus virginianus) from Ossabaw Island, Georgia (USA), were tested for antibodies to bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). During this period, prevalence of precipitating antibodies to BTV and EHDV as determined by agar gel immunodiffusion (AGID) tests decreased from 74% to 3% and from 34% to 1%, respectively. Antibodies were detected in serum samples from 0.5-yr-old deer only during 1981, 1982, and 1983, and with few exceptions, positive serological results after 1983 were restricted to older age classes. A decrease in prevalence of precipitating antibodies to BTV and EHDV in age classes exposed during 1981 indicates that AGID results from white-tailed deer populations underestimate the extent of previous exposure to these viruses. Serum neutralization test results from AGID-positive deer indicated that BTV 11 was the principal serotype responsible for infections during 1981. Since 1983, this serotype has been replaced by BTV 13; however, there has been a low level of transmission within the herd. Infection with EHDV 2 appeared most prevalent during 1982; as with BTV 13, there has been limited transmission in this high density deer population since 1983.

Animals↗
PubMed1991

Sequential measurement of beta 2-microglobulin levels, p24 antigen levels, and antibody titers following transplantation of a human immunodeficiency virus-infected kidney allograft.

A renal allograft recipient developed symptoms suggestive of AIDS. Serological studies revealed that the donor was positive for human immunodeficiency virus (HIV). Retrospective testing of stored sequential serum samples showed that the recipient was negative for HIV pretransplant; anti-p24 and anti-p41 antibodies appeared 10 and 49 days posttransplant, respectively. The recipient's serum beta 2-microglobulin levels were elevated 14 days posttransplant, with normal renal function, 35 days before the detection of anti-p24 antibody. p24 Antigen was detected for the first time 21 days posttransplant. In addition to p24 antigen, elevated serum beta 2-microglobulins may be a useful marker for HIV infection prior to seroconversion.

Adult↗
PubMed1990

Increased monoclonal antibody ascites production in mice primed with Freund's incomplete adjuvant.

The production of monoclonal antibodies is conveniently achieved by propagation of antibody-secreting hybridoma cells as ascites tumours in mice. With a view to improve production and minimise animal usage, the choice of primer (pristane or Freund's incomplete adjuvant (FIA] and the effect of sex of mouse (female vs. uncastrated male) upon antibody yields were compared. The volume of ascitic fluid harvested from 134 FIA-primed mice was 697 ml, which was significantly (P less than 0.02) greater than the 343 ml collected from 116 pristane-primed mice. Moreover, FIA-primed mice required tapping for only 11 days (90% in 7 days) compared to the 17 days needed for pristane-primed mice. While there was little difference between the mean IgG1 concentration (as determined by enzyme immunoassay) of both ascites pools (4.9 mg/ml compared to 4.6 mg/ml), the volume differences equated to yields of 25.5 mg/mouse and 13.5 mg/mouse respectively. The FIA-primed mice were also shown to produce on average more (P less than 0.02) ascites per day. There was no significant difference found between the yield of monoclonal antibodies obtained from either uncastrated males (22.1 mg/mouse) or females (23.1 mg/mouse). The use of FIA to prime mice for the in vivo production of monoclonal antibodies should improve the yield to over 20 mg/mouse, thereby reducing the number of mice required.

Animals↗
PubMed1989

Isolation and identification of Chlamydia psittaci from pet birds.

Culturing of Chlamydia psittaci from pet birds requires the inoculation of a susceptible living host system with suspensions of various tissues from dead birds or with tracheal and/or cloacal swabs and fresh feces from live birds. Cell cultures have been used as the host system. The most commonly used cell cultures for isolation of C psittaci from pet birds are McCoy and mouse L cells. The sensitivity and specificity of cell culture equals or surpasses embryonating chicken eggs and mice, and results can be obtained in less than 7 days. To obtain satisfactory results, the inoculum must be centrifuged onto the cell cultures at 37 C, and the cells must be treated with a metabolic inhibitor such as colchicine or cycloheximide. Chlamydia psitaci can be detected in infected cells by use of fluorescent antibody, Giemsa, or Gimenez staining.

Animals↗
PubMed1989

Albumin uptake by renal lymphatics with and without obstruction of the renal vein.

Experiments involving injection of radio-iodinated albumin into the left renal arteries or left ureters of dogs indicate that the renal lymphatics are capable of a major contribution in returning to the circulation albumin (or other large molecules) escaping from renal capillaries. I131-albumin was injected into the jugular vein of controls or into the left renal artery or in retrograde manner into the left ureter of female dogs. Experimental groups included those with no obstruction, occlusion of left renal veins or left renal lymphatics, or both. Collections were made from the right femoral artery, both renal veins, thoracic duct and both ureters at frequent intervals for 2 to 4 hours. Data analysis included I131 concentration, specific activity, rate of recovery and selected ratios. After renal arterial injection, the percentage of I131 recovered in thoracic duct lymph of dogs without renal venous obstruction was 5 to 10 times that recovered in those that received injections into the jugular vein. In dogs with renal venous obstruction, recovery from the thoracic duct was 10 to 1,000 times that in control dogs. Most of the differences occurred during the first hour, after which time as recirculation and redistribution occurred the rates of appearance in thoracic duct lymph in each group were similar. The differences in the ratios of concentration in thoracic duct lymph to concentration in femoral arterial blood were also much greater when the renal vein was obstructed than in dogs with no obstruction. The greater return of albumin through the thoracic duct in those with impeded renal venous outflow was probably related to both sequestered concentration and increased intrarenal pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗
PubMed1988

Effect of particle size on the in vitro and in vivo degradation rates of poly(DL-lactide-co-glycolide) microcapsules.

Three different sieve size fractions of ergot-containing biodegradable microcapsules were examined both in vitro and in vivo. The sieve sizes and average particle diameter, (micron), were: less than 45-75 (mean = 30); 75-106 (mean = 79); 106-177 (mean = 130). These microcapsules contained ca. 9% drug and were produced from 50:50 poly(DL-lactide-co-glycolide). The objective was to determine the effect of particle size on in vivo and in vitro degradation rates. The microcapsules were injected into rat gastrocnemius muscle and excised and examined at various time points up to 70 days. Initially a minimal tissue response was noted which was characterized by a sharply localized acute inflammatory reaction. Following this, connective tissue and foreign body giant cells engulfed the microcapsules at 20-30 days. Only vestiges of the microcapsules were found surrounded by minimal connective tissue and foreign body giant cells after 60-70 days. The tissue reaction was a minimal, sharply localized foreign body giant cell and connective tissue process for all three size groups of microcapsules. The largest microcapsules (mean = 130 microns) exhibited a slightly greater tendency to undergo in vivo and in vitro degradation relative to the other groups. However, it can be concluded that over the microcapsule size ranges examined minimal differences in the degradation properties of the polymeric matrices and consequently those of the microcapsules were noted.

Animals↗
PubMed1986

Transmissibility and abortogenic effect of equine viral arteritis in mares.

A group of 14 pregnant mares was exposed via contact to 4 mares bred to stallions infected with equine viral arteritis virus. There was a demonstrable febrile response in each donor mare and in 12 of the pregnant mares. All 18 mares became seropositive after exposure. Equine viral arteritis virus was isolated from the nasopharynx of 5 pregnant mares, but not from the donor mares. Ten of the pregnant mares aborted, and virus was isolated from fetal specimens or placenta of 8.

Abortion, Veterinary↗
PubMed1985

Biodegradation of and tissue reaction to 50:50 poly(DL-lactide-co-glycolide) microcapsules.

The biodegradation of the copolymer 50:50 poly(DL-lactide-co-glycolide)-lypressin microcapsules was studied by light and electron microscopic methods and 14C release. Intramuscular injection sites of microcapsules in rats were studied by dissecting and conventional light microscopy as well as scanning (SEM) and transmission electron microscopy. A minimal localized acute myositis was seen initially at the injection sites. By Day 4, a few small foreign body giant cells were present participating in the minimal foreign body response. Later the inflammatory cells decreased and the individual microcapsules were walled off by immature fibrous connective tissue and large syncytial foreign body giant cells. By Day 35, definitive changes in some microcapsules, consisting of a granular and slightly eroded appearance of the internal matrix, were seen by SEM. By Day 42, the outer rims of the microcapsules were extensively eroded. At Day 56, the inflammatory and connective tissue reactions were almost completely resolved and biodegradation continued so that only remnant pieces of the microcapsules were present at Day 63. The morphologic picture correlated well with loss of 14C radioactivity, which could no longer be detected at the injection sites on Day 56. Phagocytosis did not seem to be an important factor in the biodegradation.

Animals↗
PubMed1985

Failure of cyclo (His-Pro) to exhibit natriuretic activity.

Administration of exogenous cyclo (His-Pro) to dogs has been reported to elicit natriuresis. In contrast, our data fail to show any natriuretic activity of cyclo (His-Pro) in dogs or rats. The possible reasons underlying this discrepancy are discussed.

Animals↗
PubMed1985

Characterization of virulent and avirulent A/chicken/Pennsylvania/83 influenza A viruses: potential role of defective interfering RNAs in nature.

In April 1983, an influenza virus of low virulence appeared in chickens in Pennsylvania. Subsequently, in October 1983, the virus became virulent and caused high mortality in poultry. The causative agent has been identified as an influenza virus of the H5N2 serotype. The hemagglutinin is antigenically closely related to tern/South Africa/61 (H5N3) and the neuraminidase is similar to that from human H2N2 strains (e.g., A/Japan/305/57) and from some avian influenza virus strains (e.g., A/turkey/Mass/66 [H6N2]). Comparison of the genome RNAs of chicken/Penn with other influenza virus isolates by RNA-RNA hybridization indicated that all of the genes of this virus were closely related to those of various other influenza virus isolates from wild birds. Chickens infected with the virulent strain shed high concentrations of virus in their feces (10(7) 50% egg infective dose per g), and the virus was isolated from the albumin and yolk of eggs layed just before death. Virus was also isolated from house flies in chicken houses. Serological and virological studies showed that humans are not susceptible to infection with the virus, but can serve as short-term mechanical carriers. Analysis of the RNA of the viruses isolated in April and October by gel migration and RNA-RNA hybridization suggested that these strains were very closely related. Oligonucleotide mapping of the individual genes of virulent and avirulent strains showed a limited number of changes in the genome RNAs, but no consistent differences between the virulent and avirulent strains that could be correlated with pathogenicity were found. Polyacrylamide gel analysis of the early (avirulent) isolates demonstrated the presence of low-molecular-weight RNA bands which is indicative of defective-interfering particles. These RNAs were not present in the virulent isolates. Experimental infection of chickens with mixtures of the avirulent and virulent strains demonstrated that the avirulent virus interferes with the pathogenicity of the virulent virus. The results suggest that the original avirulent virus was probably derived from influenza viruses from wild birds and that the virulent strain was derived from the avirulent strain by selective adaptation rather than by recombination or the introduction of a new virus into the population. This adaptation may have involved the loss of defective RNAs, as well as mutations, and thus provides a possible model for a role of defective-interfering particles in nature.

Animals↗