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N C Pedersen

Publications and source records attributed to N C Pedersen.

At least 145 records · Page 8Linked to original sources
PubMed1987

Feline leukemia virus envelope protein expression encoded by a recombinant vaccinia virus: apparent lack of immunogenicity in vaccinated animals.

We have constructed a recombinant vaccinia virus encoding the expression of the feline leukemia virus (FeLV) envelope gene of the Gardner-Arnstein strain of FeLV subgroup B. Human cells infected with the recombinant virus (vFeLVenv) express and process the FeLV envelope protein similarly to cells infected with authentic FeLV. The mature gp 70 protein is transported to and accumulates on the surface of vFeLVenv-infected cells. Vaccinia virus replication and FeLV gp70 accumulation was also observed in cells of feline and murine origin, albeit at levels somewhat reduced from those in human cells. Toward the goal of developing a recombinant vaccinia virus as a live vaccine for feline leukemia disease in cats, immunogenicity studies were performed in cats and mice. These experiments yielded surprising results: although animals mounted a typical virus-neutralizing antibody response to the vaccinia virus vector, we were unable to detect antibodies against FeLV gp70 in any of the vaccinated animals. A subsequent 'booster' immunization with killed FeLV was unable to elicit evidence of immunologic 'priming' by the recombinant virus. We are presently unable to explain the apparent lack of immunogenicity. These results may point to complexities involved in the development of vaccines to protect against retrovirus infection.

Animals↗
PubMed1987

Comparison of indirect immunofluorescence and Western blot for detection of anti-human immunodeficiency virus antibodies.

There was 100% agreement between the results of indirect immunofluorescence (IF) and Western blot testing when these methods were used to detect antibodies to the human immunodeficiency virus in sera from 25 patients with acquired immune deficiency syndrome (AIDS), 20 patients with AIDS-related complex, 186 subjects at high risk for AIDS, and 40 healthy heterosexuals. However, there was only an 88.7% correlation between IF and Western blot results for 728 sera from blood and plasma donor centers that were selected on the basis of screening enzyme immunoassay reactivity. IF tests yielded nine false-negatives and were equivocal, yielding a nonspecific pattern of reactivity for both infected and uninfected cells for 73 of these specimens. The IF and Western blot methods were equal in performance for the detection of anti-human immunodeficiency virus antibodies in the high-risk and unselected low-risk groups, proving to be a practical approach for testing specimens from these subjects. However, the Western blot was the most acceptable method for the validation of specimens from groups at low risk for AIDS that were selected based on enzyme immunoassay reactivity.

AIDS-Related Complex↗
PubMed1987

Unique p24 epitope marker to identify multiple human immunodeficiency virus variants in blood from the same individuals.

The human immunodeficiency virus (HIV) was isolated from the blood of 192 of 410 seropositive individuals. Original isolations were made in peripheral blood mononuclear cell (PBMC) cultures, and only one-fifth of the HIV isolates could be adapted to replicate in continuous T-cell lines. Of the 192 HIV isolates, 42 had the characteristic p24 antigen marker of the acquired immunodeficiency syndrome-associated retrovirus type 2 strain of HIV (HIV ARV-2) and 150 resembled the human T-cell lymphotropic virus type III strain of HIV (HIV HTLV-III). Significantly, primary PBMC cultures from two patients yielded multiple variants. When these variants were exposed to continuous T-cell lines, only one of them continued to replicate. The remaining variants were lost and could not be reisolated following passage back into PBMC cultures. We conclude the following from these studies: PBMC cultures are more efficient at isolating HIV than continuous T-cell lines are; some patients harbor more than one genetic variant of HIV in the blood at the same time; and continuous T-cell lines are likely to yield only a portion of the HIV variants originally present in the blood.

Antigens, Viral↗
PubMed1987

Viremia, antigenemia, and serum antibodies in rhesus macaques infected with simian retrovirus type 1 and their relationship to disease course.

The course of simian retrovirus type 1 (SRV-1) infection was studied in 14 experimentally inoculated juvenile rhesus monkeys. Viral transmembrane protein antigenemia and antibodies to whole virus were measured by enzyme linked immunosorbent assay and correlated with the clinical course of disease and virus isolation. Based on these parameters, animals with simian retrovirus type 1-induced disease were divided into three categories: monkeys dying within a few months of fulminating simian acquired immune deficiency syndrome in the face of a high level persistent antigenemia and viremia, and a nondetectable serum antibody response; monkeys that developed a milder form of simian acquired immune deficiency syndrome but remained alive in spite of a chronic low-grade antigenemia and viremia and only a transient initial antibody response; and monkeys that never became ill and that were either transiently or nontransiently viremic and antigenemic. This latter group developed high levels of serum antibodies. The outcome of simian retrovirus type 1-induced disease was similar to that described for feline leukemia virus infection of cats, another retroviral disease of animals. The disease course differed considerably, however, from that reported for retrovirus-induced human acquired immune deficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Seroepidemiologic survey of captive Old-World primates for antibodies to human and simian retroviruses, and isolation of a lentivirus from sooty mangabeys (Cercocebus atys).

Sera from 526 Old-World monkeys and apes, representing 50 species and 20 genera and living in US zoos and vivaria, were screened for antibodies to HTLV-I, HTLV-III/LAV, and simian-AIDS retrovirus, type I (SRV-I). Sera were screened initially by ELISA, and ELISA-positive sera, as well as ELISA-negative sera from cage contacts, were further tested by Western blotting. A large number of false-positive and a small number of false-negative ELISA sera were identified. Although most true positive reactions were directed to a single retrovirus, a number of individuals from 4 species were positive for more than one retrovirus. Specific seroreactivity to HTLV-I was found in 39/526 (7%) animals of 15 species. True positive reactions to SRV-I were found in 21/516 (4%) animals, including talapoins and 2 species of macaques. Specific serologic reactions to HTLV-III/LAV were detected in 23/526 (4%) monkeys. Many of the HTLV-III/LAV seropositive animals were from one mixed-species zoo exhibit, containing sooty mangabeys, mandrills, Kolb's guenons, and talapoins. A type D virus was isolated from the blood of 3/10 SRV-I antibody-positive Tonkeana macaques, but from none of 11 seropositive talapoins. A lentivirus was isolated from the blood of 4/7 HTLV-III/LAV seropositive sooty mangabeys, but not from seropositive talapoins in the same exhibit or from 2 seropositive colobus from another zoo. The sooty mangabey lentivirus produced generalized lymphadenopathy, leukopenia, and decreased levels of T4 lymphocytes in 2 experimentally infected rhesus macaques.

Animals↗
PubMed1986

Use of tears for diagnosis of feline leukemia virus infection.

A comparison was made of the use of serum, tears, and saliva for the detection of feline leukemia virus (FeLV) infection in cats. Cotton swabs were used to collect saliva, and tear-test strips were used to collect tears. Specimens were analyzed by a commercially available ELISA. Using a 10- to 15-minute specimen incubation period, FeLV was detected in 70% of the saliva specimens and in 73% of the tear specimens from viremic (serum-positive) cats. Feline leukemia virus antigen was not detected in saliva and tear specimens from serum-negative cats. The sensitivity of the tear assay was improved by increasing the incubation time to 24 hours. Tear strips could be air-dried and stored at room temperature for up to 7 days without any appreciable loss of activity. Client-owned and experimentally infected laboratory cats were tested for FeLV, using air-dried tear-test strips and a 24-hour incubation period. Tears were positive (contained FeLV antigen) in 65 of 72 (90%) serum-positive cats and did not contain antigen in 46 of 46 (100%) serum-negative cats. Results of ELISA obtained from serum and tears also were compared with results obtained from indirect fluorescent antibody testing of blood smears. Results of indirect fluorescent antibody and ELISA compared favorably with each other and with the results of tear testing.

Animals↗
PubMed1986

Monoclonal antibodies to the v-fes product and to feline leukemia: virus P27 interspecies-specific determinants encoded by feline sarcoma viruses.

Monoclonal antibodies to p27 gag and v-fes specific determinants on the gag-onc poly-protein encoded by Snyder-Theilen feline sarcoma virus (ST-FeSV) were prepared. In order to obtain hybridoma clones specific to the antigenic determinants encoded by the FeSV genome, Lou rats were immunized with ST-FeSV-transformed, virus-nonproducing syngeneic cells, and boosted with either the same cells or affinity-purified feline leukemia virus (FeLV) p27. Three distinct clones reactive to both FeLV p27 and p85gag-fes, and one clone specific for a p85fes determinant were established. The anti-p27 monoclonal antibodies also reacted with the polyproteins p95gag-fes and p83gag-fgr, from Gardner-Arnstein (GA) and Theilen-Pedersen (TP1) FeSV, respectively. The anti-p27 monoclonal antibodies reacted with MuLV p30 and RD114 p28 but not with RSV, MMTV, or BLV. These results indicated that the part of the p27 gag gene that is preserved in ST-, GA, and TP1-FeSV encodes interspecies-specific p27 determinants.

Animals↗
PubMed1986

A feline retrovirus induced T-lymphoblastoid cell-line that produces an atypical alpha type of interferon.

A cell-line, designated LSA-1, was derived from a thymic lymphosarcoma that occurred in a cat with experimentally induced feline leukemia virus (FeLV) infection. LSA-1 cells possessed surface receptors and antigens of normal T-lymphocytes, but were unresponsive to interleukin-2 stimulation. The LSA cell-line was found to constitutively produce and release an interferon into the culture supernatants. Production of this interferon was enhanced in certain clones of the original LSA-1 cell lines. The interferon produced by LSA-1 cells and some of its clones was compared to the standard alpha, beta, and gamma interferons of cats. Unlike alpha and beta interferons, which were acid, SDS, and heat stable, LSA interferon was acid labile and SDS and heat stable. In comparison, standard feline gamma interferon was acid, SDS, and heat labile. LSA interferon had a molecular weight of 20,000 daltons, compared to 17-19,000 daltons for gamma, 19-25,000 for beta, and 25-45,000 daltons for alpha interferons. Standard feline interferons were active only on cat cell lines, with the exceptions of alpha interferon, which also reacted with MDCK canine cells. LSA interferon resembled the standard feline alpha interferon because it also reacted with feline and canine cells. It was concluded that LSA interferon was an atypical acid labile alpha interferon, resembling in this respect the abnormal alpha interferon seen in humans with AIDS and SLE, and mice with retrovirus infections. LSA-1 cells produced high levels of FeLV structural proteins but very little infectious virus. This effect was due to endogenously produced interferon; LSA cell clones that were selected for low interferon production produced much higher levels of infectious FeLV than parent cells or clones selected for high interferon production. Cat cells pretreated with LSA or with standard feline alpha and beta interferons, and then infected with FeLV, produced high levels of FeLV proteins but very little infectious virus.

Acids↗
PubMed1986

Possible immunoenhancement of persistent viremia by feline leukemia virus envelope glycoprotein vaccines in challenge-exposure situations where whole inactivated virus vaccines were protective.

Kittens immunized with purified native FeLV-gp70 or -gp85 envelope proteins developed ELISA, but not virus neutralizing, antibodies in their serum to both whole FeLV and FeLV-gp70. Kittens vaccinated with envelope proteins and infected with feline sarcoma virus (FeSV) developed smaller tumors than nonvaccinates, but a greater incidence of persistent retroviremia. Similarly, FeLV-gp70 and -gp85 vaccinated kittens were more apt to become persistently retroviremic following virulent FeLV challenge exposure than nonvaccinates. Kittens vaccinated with inactivated whole FeLV developed smaller tumors after FeSV inoculation and had a lower incidence of persistent retroviremia than nonvaccinates. The protective effect of inactivated whole FeLV vaccine against persistent retroviremia was also seen with FeLV challenge-exposed cats. Protection afforded by inactivated whole FeLV vaccine was not associated with virus neutralizing antibodies, although ELISA antibodies to both whole FeLV and FeLV-gp70 were induced by vaccination.

Animals↗
PubMed1986

The causes of false-positives encountered during the screening of old-world primates for antibodies to human and simian retroviruses by ELISA.

Sera from 526 old-world primates representing 50 different species were screened by ELISA for antibodies to human T-lymphotropic viruses I and III, and simian retrovirus type 1 (SRV-1). About one-fourth of the sera were positive by ELISA. There was a tendency, however, for the same sera to be positive for all three human and simian retroviruses. Only about one in five of the ELISA antibody-positive sera were confirmed to be positive by Western blotting. False-positive ELISA antibody tests were particularly common among sera from mandrills, crab-eating macaques, lion-tailed macaques, African green monkeys, and DeBrazza's and moustached guenons. Sera that were falsely positive in ELISA antibody tests to the three human and simian retroviruses were found to contain antibodies that reacted at comparable intensity with feline leukemia, infectious peritonitis and panleukopenia viruses. The false anti-viral activity of these sera was found to be due to antibodies that reacted with non-viral proteins that were copurified with all five virus preparations. These proteins were present in normal cat and human cells used to grow the various viruses and in gelatin. The implications of nonspecific cell-protein antibodies in primate sera were discussed in the light of this and previous seroepidemiologic studies of man and old-world monkeys.

Animals↗
PubMed1986

Human alpha- and beta-interferon but not gamma- suppress the in vitro replication of LAV, HTLV-III, and ARV-2.

The effect of human interferons (IFNs) (alpha, beta, and gamma) on the in vitro replication of AIDS viruses (LAV, HTLV-III, and ARV-2) in human peripheral blood lymphocytes was investigated. At the time of peak virus production, IFN-alpha preparations (leukocyte, Namalwa, alpha 1, and alpha 2) at 100 U/ml, suppressed LAV, HTLV-III, and ARV-2 replication as measured by reverse transcriptase (RT) activity by greater than 50%. This suppression was dose dependent and high dosages (500 U/ml) of IFN-alpha resulted in almost complete suppression of RT activities (77-99%). A low dose (100 U/ml) of IFN-beta suppressed all three AIDS viruses by 75%. In contrast, human IFN-gamma at a dose range from 100 U/ml to 500 U/ml had no significant effect on the production of infectious viruses. These results indicate that only IFN-alpha and -beta are effective against LAV, HTLV-III, and ARV-2 replication. A continuous supply of IFN appeared to be essential for the constant suppression of RT activity. In fact, upon termination of single IFN treatment, enhanced virus production resulted.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Evaluation of three commercial screening tests for AIDS virus antibodies.

Three commercial enzyme-linked immunosorbent assays (ELISA) for acquired immune deficiency syndrome (AIDS) virus antibodies were evaluated using serum that had been characterized by an ELISA and western blot procedure developed at the University of California at Davis (UCD). Each of the commercial tests was more specific than the UCD ELISA, but the UCD ELISA was more sensitive in the detection of sera that lacked reactivity by western blot to the envelope glycoprotein (gp-41). The HTLV-III Bio-EnzaBead (Litton Bionetics, Charleston, SC) was less sensitive and specific than the Abbott HTLV-III EIA (Abbott Laboratories, North Chicago, IL) or the Virgo HTLV-III ELISA (Electro-Nucleonics Inc., Columbia, MD). Overall, 22.9% (57 of 250) and 51.0% of sera that were repeatedly (X2) positive by commercial screening kits tested at blood donor centers and clinical laboratories, respectively, were confirmed by western blot. These results indicate that the screening assays for AIDS virus antibodies are not equal in performance and that positive screening test results must be confirmed by a more specific test like western blot before results are released.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Detection and differentiation by sandwich enzyme-linked immunosorbent assay of human T-cell lymphotropic virus type III/lymphadenopathy-associated virus- and acquired immunodeficiency syndrome-associated retroviruslike clinical isolates.

Monoclonal antibodies can be used in sandwich enzyme-linked immunosorbent assays to measure viral antigens. Such an assay was developed to detect the core protein, p24, of human T-cell lymphotropic virus type III and lymphadenopathy-associated virus, etiologic agents of the acquired immunodeficiency syndrome (AIDS). Another AIDS-associated virus, AIDS-associated retrovirus type 2 (ARV-2) could not be detected in this assay because of the low affinity of one of the monoclonal antibodies to ARV-2 p24. Detection of ARV-2 was accomplished with a monoclonal antibody-rabbit polyclonal antibody sandwich enzyme-linked immunosorbent assay. These two assays were used to efficiently detect AIDS-related viruses in lymphocyte cell cultures and to distinguish strains of the viruses.

AIDS-Related Complex↗
PubMed1986

Prevention of simian acquired immune deficiency syndrome with a formalin-inactivated type D retrovirus vaccine.

Experimental induction of simian acquired immune deficiency syndrome (SAIDS) by inoculation of juvenile rhesus monkeys with a type D retrovirus was prevented by immunization with Formalin-killed whole SAIDS retrovirus serotype 1 containing the adjuvant threonyl muramyl-dipeptide. All six immunized animals developed neutralizing antibody after three injections, while six age-matched cagemates receiving adjuvant alone were antibody free. All 12 monkeys were challenged intravenously with a potentially lethal dose of SAIDS retrovirus serotype 1. The six immunized animals failed to develop persistent viremia and remained clinically normal 8 months postchallenge. In contrast, five of six nonvaccinates developed persistent viremia, four of six developed clinical SAIDS, and two of six died with SAIDS at 10 weeks and 8 months postchallenge, respectively. These results show that prevention of a common spontaneous retrovirus-induced immunosuppressive disease in macaques is now possible by vaccination.

Acquired Immunodeficiency Syndrome↗
PubMed1985

The nature of immunity to Snyder-Theilen fibrosarcoma virus induced tumors in cats.

Snyder-Theilen fibrosarcoma virus (ST-FeSV) induced tumors evoked a vigorous immune response in adolescent cats. The response was characterized histologically by a lymphoid and histiocytic cell infiltrate beginning around the 9th day post inoculation. Hyperemia edema, hemorrhage, and necrosis of the tumors occurred shortly thereafter. Gross regression of the tumors commenced around the 15th day. Viable fibrosarcoma cells could be recovered as almost pure cultures from tumors biopsied on the 9th day. Biopsies taken between days 9 and 15 contained progressively fewer tumor cells and increasing numbers of lymphoid cells, histiocytes, giant cells, and normal fibroblasts. Tumor cells in such mixed cultures did not replicate as fast as normal and died out within 7 to 14 days. Viable tumor cells were not recovered from biopsies taken after day 15. Fibrosarcoma regression was associated with the appearance of tumor cell specific cytotoxic lymphocytes and antibodies in the blood. Cell mediated immunity, as determined by a chromium release assay, consisted of both antibody dependent and independent mechanisms. Fluorescent and complement dependent cytolytic antibodies were detected in the blood at the same time as cytotoxic lymphocytes, but persisted after regression. In a preliminary experiment, serum from tumor regressor cats was injected into susceptible kittens, and the kittens were then challenged with ST-FeSV transformed fibroblasts or whole FeSV. Immune serum did not prevent the appearance of initial growth of tumors, but did slow their subsequent growth and increased the rate of regression. Immune serum had a much more dramatic inhibitory effect on the accompanying retrovirus infection.

Animals↗
PubMed1985

Competitive enzyme immunoassays for the rapid detection of antibodies to feline infectious peritonitis virus polypeptides.

Monoclonal antibodies specific for the envelope (E1), peplomer (E2), and nucleocapsid (N) polypeptides of feline infectious peritonitis virus (FIPV) were used in rapid, competitive enzyme-linked immunosorbent assays (ELISA) to study the humoral immune response of cats to FIPV infection. Results from the competitive ELISAs were correlated with those from immunofluorescent antibody assays (IFAs) on 203 samples obtained from 64 individual cats. The IFA results correlated best with those obtained with the anti-E1 specific competitive ELISA (85.7%). In contrast, anti-N and anti-E2 competitive ELISA results correlated with IFA results only 65.5 and 2.4% of the time, respectively. The results of the anti-E1 specific competitive ELISA were not influenced by the total immunoglobulin concentration or the possible presence of free viral antigens in the serum. These results suggest that a competitive ELISA involving the use of enzyme-conjugated monoclonal antibody to the E1 glycoprotein of FIPV is a simple and rapid replacement for the more cumbersome IFA.

Animals↗
PubMed1984

Biological and biochemical characterization of a new isolate of feline sarcoma virus: Theilen-Pedersen (TP1-FeSV).

A new feline sarcoma virus designated Theilen-Pedersen (TP1-FeSV) has been isolated from a spontaneous, slowly growing fibrosarcoma of a domestic short-haired 4-year-old castrated cat. The virus codes for a gag-onc fusion protein of 83,000 molecular weight phosphorylated in vivo at serine, threonine, and tyrosine residues. Cells transformed in vitro with TP1-FeSV exhibit five- to 10-fold elevated levels of phosphotyrosine over FeLV-infected cells. The gag-onc polyprotein has associated with it a tyrosyl protein kinase activity which in vitro results in autophosphorylation of the molecule at tyrosine residues. The fusion protein cannot be labeled metabolically with [3H]glucosamine and tunicamycin has no effect on the electrophoretic mobility of the in vivo [32P]orthophosphate-labeled fusion protein. The fusion protein, in common with the gag precursor Pr65gag, can be metabolically labeled with palmitic acid.

Acylation↗