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J F Young

Publications and source records attributed to J F Young.

At least 91 records · Page 5Linked to original sources
PubMed1987

Expression at the cell surface of native fusion protein of the Newcastle disease virus (NDV) strain Italien from cloned cDNA.

A cDNA library was constructed with poly(A)+-mRNAs from NDV-Italien infected BHK-21 cells. A clone, that hybridized to the F gene mRNA, was sequenced. A long open reading frame encodes for a protein of 553 amino acids, with a calculated molecular weight of 59,153, consisting of twelve cysteine residues and six potential glycosylation sites. The protein sequence contains a hydrophobic region at the N-terminus of F1 and a presumptive long transmembrane fragment near the C-terminus. Comparison of the F proteins from NDV strains Italien and Australia-Victoria shows that the sequences are very similar, with conservation of most cysteine residues and of the potential glycosylation sites. The F coding sequence was inserted into the genome of vaccinia virus under the control of vaccinia P7.5 transcriptional regulatory sequences. Expression of F protein was demonstrated by indirect immunofluorescence with five anti-F monoclonal antibodies known to react with conformational epitopes.

Amino Acid Sequence↗
PubMed1987

Retinoic acid induction of stress proteins in fetal mouse limb buds.

Retinoic acid (RA) is teratogenic in rodent embryos. Several teratogens have been shown to induce the synthesis of a subset of heat shock proteins (stress proteins) in Drosophila. To determine if RA induces the synthesis of these proteins in rodent embryos, pregnant ICR mice were dosed with 100 mg/kg RA on Day 11 of gestation. Forelimb buds were removed from embryos 2.5 hr post-RA-treatment and nuclei were isolated, stained, and sorted from stages of the cell cycle. Nuclear proteins were extracted and analyzed by two-dimensional polyacrylamide gel electrophoresis. Nuclear proteins with molecular weights of approximately 84 and 25 kDa were synthesized in embryos in the G0 + G1 phase after pregnant dams were treated with RA. Isoelectric points, molecular weights, immunochemical blotting, and polypeptide mapping demonstrated that these proteins are indistinguishable from stress proteins isolated under a variety of conditions from rat submaxillary glands and mouse lymphoma cells. These results suggest that treatment with RA induces the synthesis of a subset of stress proteins; the role of these proteins in the teratogenic effects of RA is not known.

Animals↗
PubMed1987

Plasmodium falciparum: sporozoite boosting of immunity due to a T-cell epitope on a sporozoite vaccine.

Plasmodium falciparum: Sporozoite boosting of immunity due to a T-cell epitope on a sporozoite vaccine. Experimental Parasitology 64, 64-70. The impact of a malaria sporozoite vaccine may be enhanced if protective immunity elicited by the vaccine is boosted by natural exposure to sporozoites. For this to occur, a helper T lymphocyte epitope present on the vaccine must be shared by sporozoites. These studies show that T cells from mice immunized with R32tet32, the Plasmodium falciparum sporozoite vaccine candidate, recognize an epitope of less than or equal to 7 amino acids derived from the circumsporozoite protein repeat region of R32tet32, as well as an epitope on the tet32 fusion protein tail of R32tet32. Exposure of R32tet32 immunized animals to P. falciparum sporozoites elicits a significant secondary antibody response which suggests that humans who are immunized and respond to this vaccine may be boosted by field exposure to sporozoite infected mosquitoes.

Animals↗
PubMed1987

Plasmodium falciparum: immunogenicity of circumsporozoite protein constructs produced in Escherichia coli.

The immunogenicity of Plasmodium falciparum recombinant circumsporozoite protein constructs R16tet32, R32tet32, and R48tet32 in mice was examined by measuring antibody responses by enzyme linked immunosorbent assay, immunofluorescence, circumsporozoite precipitation, and inhibition of sporozoite invasion. All three constructs were found to be immunogenic when administered alone, but antibody responses were greater for the larger constructs, R32tet32 and R48tet32. Increased dose, boosting, and the use of adjuvants further augmented antibody responses. R32tet32 was found to be the most immunogenic of the three constructs, and high levels of protective antibodies were found to persist for at least 44 weeks when the construct was given with alum. Clinical trials with alum adjuvanted R32tet32 have now begun.

Adjuvants, Immunologic↗
PubMed1987

Plasmodium falciparum: elicitation by peptides and recombinant circumsporozoite proteins of circulating mouse antibodies inhibiting sporozoite invasion of hepatoma cells.

The immunodominant epitope region of the circumsporozoite protein of Plasmodium falciparum sporozoites contains 37 tandem repeats of the tetrapeptide Asn-Ala-Asn-Pro and 4 repeats of Asn-Val-Asp-Pro. Synthetic peptides and recombinant proteins of the repeat region were used to immunize mice using different doses and adjuvants. Antisera were tested for inhibition of sporozoite invasion of cultured human hepatoma cells. Synthetic peptides and recombinant proteins elicited high levels of antibodies that inhibited sporozoite invasion when emulsified with complete Freund's adjuvant. Since recombinant proteins with alum elicited a better antibody response to sporozoite invasion than they did without adjuvant, it may be that a recombinant protein containing 32 tandem copies of the tetrapeptide repeat combined with alum could be a candidate malarial vaccine suitable for human trials.

Animals↗
PubMed1987

Augmentation of human natural killer cell activity by influenza virus antigens produced in Escherichia coli.

A series of Escherichia coli cloned influenza viral gene products were assayed for their ability to augment human natural cytotoxicity in overnight cultures (18 h) at 37 degrees C. Nylon wool nonadherent peripheral blood mononuclear cells (PBMC) proved responsive to stimulation by a number of cloned viral proteins, the most effective being the nonstructural (NS1) protein (but not NS2 protein) and haemagglutinin and matrix antigen components fused to the N-terminal 81 amino acid sequence of NS1. Furthermore, interferon (IFN) was generated in cultures in which enhanced cytotoxicity was detected and was identified as mostly IFN alpha (greater than 90%) with less than 10% IFN gamma contamination. The cell type responding to antigen stimulation was present in Percoll fractions enriched for large granular lymphocytes (LGLs); furthermore PBMC activated by NS1 protein fractionated in the low density Percoll fractions (LGL enriched). Using specific anti-IFN antisera, it was shown that IFN alpha but not IFN gamma was responsible for the enhancement of cytotoxicity. Interferon induction and activation of cytotoxicity could not be ascribed to the presence of contaminating bacterial products. These results suggest that a particular NS1 protein configuration is capable of activating human natural killer cells via the induction of IFN alpha.

Antigens, Viral↗
PubMed1985

Influenza virus subtype-specific cytotoxic T lymphocytes lyse target cells coated with a protein produced in E. coli.

We have tested the ability of the c13 protein, which is a hybrid protein of the first 81 amino acids of the viral nonstructural protein (NS1) and the HA2 subunit of viral hemagglutination produced in E. coli, to render target cells susceptible to the lytic activity of influenza virus-specific cytotoxic T lymphocytes (CTL). The results showed that P815 cells coated with c13 protein were lysed by PR8 virus-induced secondary CTL derived from BALB/c mice. Cold-target inhibition tests clearly demonstrated that c13 protein-coated P815 cells were recognized by an H1 subtype-specific CTL population. Furthermore, PR8 virus-induced CTL derived from C3H mice did not lyse c13 protein-coated P815 cells, suggesting that c13 protein was recognized by CTL in conjunction with H-2d products. These findings suggest that this protein interacts with the cellular plasma membrane and makes target cells recognizable by H-2-restricted, influenza virus subtype-specific CTL.

Animals↗
PubMed1985

Influenza virus hemagglutinin-specific cytotoxic T cell response induced by polypeptide produced in Escherichia coli.

We have tested the abilities of various polypeptides of A/PR/8/34 (H1N1) virus, constructed by recombinant DNA techniques, to induce influenza virus-specific secondary cytotoxic T lymphocyte (CTL) responses. A hybrid protein (c13 protein), consisting of the first 81 amino acids of viral nonstructural protein (NS1) and the HA2 subunit of viral hemagglutinin (HA), induced H-2-restricted, influenza virus subtype-specific secondary CTL in vitro, although other peptides did not. Using a recombinant virus, the viral determinant responsible for recognition was mapped to the HA2 portion of c13 protein. Immunization of mice with c13 protein induced the generation of memory CTL in vivo. The CTL precursor frequencies of A/PR/8/34 virus- and c13 protein-immune mice were estimated as one in 8,047 and 50,312, respectively. These results indicate that c13 protein primed recipient mice, even though the level of precursor frequency was below that observed in virus-immune mice.

Animals↗
PubMed1985

Expression of Plasmodium falciparum circumsporozoite proteins in Escherichia coli for potential use in a human malaria vaccine.

The circumsporozoite (CS) protein of the human malaria parasite Plasmodium falciparum may be the most promising target for the development of a malaria vaccine. In this study, proteins composed of 16, 32, or 48 tandem copies of a tetrapeptide repeating sequence found in the CS protein were efficiently expressed in the bacterium Escherichia coli. When injected into mice, these recombinant products resulted in the production of high titers of antibodies that reacted with the authentic CS protein on live sporozoites and blocked sporozoite invasion of human hepatoma cells in vitro. These CS protein derivatives are therefore candidates for a human malaria vaccine.

Animals↗
PubMed1984

Dietary and age influence on the pharmacokinetic parameters of 2-acetylaminofluorene in BALB/c mice.

In a chronic study conducted in our laboratories, we found dietary effects on 2-acetylaminofluorene (2-AAF) toxicity. To determine if the absorption, distribution, metabolism, or elimination of 2-AAF was altered by the age of the animals, diet, or 2-AAF treatment, pharmacokinetic studies were conducted on young (11 weeks) and old (78 weeks) BALB/c mice that had been fed one of four diets containing 4 or 24% fat and 12 or 24% protein. Blood, urine, and feces samples were obtained over a 31-hr period after dosing with 500 ppm 2-[14C]AAF (10 microCi/mouse). Total radioactivity was determined after combusting each sample in an oxygen atmosphere and counting in a scintillation counter. The data from each individual mouse was simulated on an analog-digital hybrid computer utilizing a two-compartment model with metabolism. The pharmacokinetic parameters within groups were analyzed to make statistical comparisons of the effects of diet, dose, age, and interactions among the groups. The pharmacokinetic predictions of a shorter elimination half-life, smaller area-under-the-curve value, and therefore a decreased exposure to 2-AAF and metabolites due to an increased elimination rate of the parent compound through the urine were consistent with the decreased pathological effects found from the chronic study for the low protein/low fat diet mice.

2-Acetylaminofluorene↗
PubMed1984

Blood flow changes and conceptal development in pregnant rats in response to caffeine.

Alterations in blood flow to the uterus and its contents during pregnancy have been suggested to account for the teratogenicity and/or embryotoxicity of several agents, including caffeine. Using a radioactive microsphere technique, blood flow to several maternal organs, including ovary, uterus, decidua, and chorioallantoic placenta (CAP), was measured following a single dose of 0 or 120 mg/kg caffeine by gavage to pregnant CD rats on Day 12 of gestation. At 1 or 4 hr after treatment, animals were anesthetized and strontium 85-labeled microspheres (25 micrometers diam) were infused into the left ventricle. Whole body and tissue radioactivity were determined. Maternal cardiac output (CO) and absolute flow (f1; ml/min), relative flow (f2; ml/min/g tissue), and flow as %CO (f3) to each tissue were calculated. Maternal CO was not altered. All blood flow parameters for ovaries, uterus, and bladder were reduced in treated animals at both time points except for absolute flow (f1) to the ovaries at 1 hr. Decidual changes included reduced weight at 1 hr, reduced f2 at 4 hr, and reduced f1 and f3 at both times. However, CAP weight and blood flow wre not significantly altered by caffeine treatment. Examination of conceptuses from thse litters, and from other animals at 24 hr after treatment or at term did not reveal any significant effect of this dose of caffeine on viability, growth, or physical development. The ratio of embryo to maternal blood caffeine concentrations was approximately 1, indicating free transfer of caffeine to the embryos.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

DNA adduct formation, removal and persistence in rat liver during one month of feeding 2-acetylaminofluorene.

Male Wistar-Furth rats were fed 0.02% 2-acetylaminofluorene (AAF) for 3 days or 0.02% AAF for 25 days followed by 0.02% [ring-3H]AAF for an additional 3 days. The concentration of hepatic DNA adducts was then monitored by both radioimmunoassay and radiolabeling during 28 days of control diet. This approach allowed comparisons to be made of adduct accumulation, removal and persistence at both the beginning and end of a four week carcinogen feeding period. DNA adduct formation remained constant during the month of AAF administration with an accumulation rate of 157 fmol adduct/micrograms DNA during days 1-3 and days 25-28 of the experiment. Furthermore, the rate of removal of adducts formed during these three day periods was similar when both groups were fed control diets for 28 additional days. Continued AAF administration resulted in a slow accumulation of persistent adducts; thus, 91 +/- 6% of the adducts detected after 3 days of AAF feeding were removed during a subsequent month of control diet, while only 65 +/- 11% of the adducts detected after 28 days of AAF diet were removed when rats were fed control diet for an additional 28 days. In a second experiment, the removal of adducts was compared in animals fed control or AAF diet after previously being fed 0.02% AAF for 17 days. Similar removal curves were observed in both groups; therefore, continued ingestion of AAF did not affect the rate of adduct removal. In both experiments, biphasic repair curves were observed. These data were used to develop a pharmacokinetic model. Two genomic regions were postulated, an area susceptible to fast repair and a region more resistant to the removal of AAF adducts. At equilibrium, which was reached after 2-3 weeks of AAF feeding, the concentration of adducts in each region was similar with approximately 150 fmol adduct/micrograms DNA. Although the total number of adducts formed in the fast repair region during one month of AAF administration was five times greater than in the resistant region, the model predicted that the adducts localized in regions resistant to repair were the persistent adducts detected after one month of control diet. Overall, the removal of adducts formed during chronic AAF feeding was very efficient since greater than 93% of the adducts were removed by the end of a subsequent month of control diet.

2-Acetylaminofluorene↗
PubMed1984

Sporadic occurrence of zoonotic swine influenza virus infections.

Two infections by swine influenza virus, antigenically similar to A/New Jersey/76 (H1N1) virus, were detected during community epidemics with other influenza viruses. The swinelike viruses were obtained during virological surveillance of acute respiratory illnesses, and the clinical symptoms of these two patients were similar to those caused by other respiratory viruses. Both patients reported contact with swine a few days before onset of illness, but in one case it was brief. Serological studies suggested that one patient may have transmitted the virus to his roommate, but spread into the community was not indicated.

Adult↗
PubMed1983

Measurement of suppressor transfer RNA activity.

Transfer RNA (tRNA) suppression of nonsense mutations in prokaryotic systems has been widely used to study the structure and function of different prokaryotic genes. Through genetic engineering techniques, it is now possible to introduce suppressor (Su+) tRNA molecules into mammalian cells. A quantitative assay of the suppressor tRNA activity in these mammalian cells is described; it is based on the amount of tRNA-mediated readthrough of a terminating codon in the influenza virus NS1 gene after the cells are infected with virus. Suppressor activity in L cells continuously expressing Su+ (tRNAtyr) was 3.5 percent and that in CV-1 cells infected with an SV40- Su+ (tRNAtyr) recombinant was 22.5 percent.

Animals↗
PubMed1983

Nonsense mutations affecting the lengths of the NS1 nonstructural proteins of influenza A virus isolates.

The proteins from cells infected with influenza A virus field isolates were labeled with [35S]methionine and analyzed by SDS-polyacrylamide gel electrophoresis. By screening more than 100 field isolates, it was found that the NS1 proteins had the greatest mobility differences, far exceeding those observed among other corresponding viral polypeptides. Partial sequence determination of RNA segment eight from 12 viruses revealed the existence of nonsense mutations at six different positions in their NS1 coding regions. The termination codons consisted of opal, ochre, and amber mutations. The sizes predicted from these sequences of 202, 217, 219, 220, 230, and 237 amino acids were in agreement with the observed mobilities of the viral polypeptides on SDS-polyacrylamide gels. The observation of large deletions in the carboxy termini of the NS1 proteins of field virus isolates would suggest that a high degree of variation can be tolerated in this polypeptide without affecting its functional capability.

Base Sequence↗
PubMed1983

Preparation of influenza virus subviral particles lacking the HA1 subunit of hemagglutinin: unmasking of cross-reactive HA2 determinants.

Acid treatment of influenza A and B virus preparations followed by addition of dithiothreitol (DTT) and centrifugation through a sucrose cushion removes the HA1 subunit of hemagglutinin from virus. Rabbit sera made against these subviral particles and untreated virus were tested in a radioimmune precipitation assay using [35S]cysteine-labeled virus. Conditions of the assay permitted discrimination of discrete HA1- and HA2-specific antibody populations. It was found that (a) sera raised to intact influenza A virus preparations contained both HA1- and HA-2 specific antibodies, (b) sera made to subviral particles of influenza A virus contained HA2-specific antibody but had little or no detectable HA1-specific antibody. (c) the HA2-specific antibodies were partially cross-reactive with the HA2 of an influenza A virus of a different subtype, and (d) sera raised against two strains of untreated influenza B viruses contained antibodies which were cross-reactive with the HA2 as well as the NP of influenza A viruses.

Cross Reactions↗
PubMed1983

Sequential mutations in hemagglutinins of influenza B virus isolates: definition of antigenic domains.

Comparative analysis of the amino acid sequences of hemagglutinins (HAs) of influenza B/Lee/40, B/Md/59, and B/HK/73 viruses has allowed examination of the molecular basis of antigenic variation in type B viruses. As seen with influenza type A viruses, antigenic drift in influenza B viruses proceeds mostly through the accumulation of amino acid substitutions within the HA1 portion of the HA molecule. However, the rate of variation observed among the influenza B virus HAs appears to be significantly lower than the observed rate of variation among influenza A virus HAs. The overall rate of amino acid change in the HA1s of the influenza B viruses studied is 2% per 10 years, whereas the HA1s of H3 influenza A viruses vary by 9.2% per 10 years. The sequences of the influenza B HAs were also examined in relation to the three-dimensional model for the A/Aichi/2/68 HA. When the primary amino acid sequences are compared, it appears that most of the important structural features of the type A HAs--such as the sialic acid binding site, the disulfide linkages, and the stem structure of the trimer--are conserved in the influenza B virus HAs. Regions are also identified where extensive amino acid substitutions have occurred among the three antigenically distinct influenza B virus HAs. The locations of these areas in the B HA structure correspond to antigenic regions proposed for the A virus HAs. In addition, modulation of antigenic regions in B virus HAs may also occur through amino acid deletions and variation in glycosylation sites.

Amino Acid Sequence↗