Search PubMed⌕ Search

Biomedical subjects

H Persson

Publications and source records attributed to H Persson.

At least 325 records · Page 18Linked to original sources
PubMed1982

An adenovirus agnogene.

The nucleotide sequence of a 550 base pairs long segment, located between map positions 21 and 22.5 in the adenovirus type 2 genome has been determined. S1 nuclease mapping and sequence analysis of cDNA copies of adenovirus mRNA demonstrated that the established sequence includes the i-leader which is spliced to the 5'-end of certain adenovirus mRNAs (1). The i-leader which is 440 nucleotides long contains an open translational reading frame which is preceded by an AUG triplet and which terminates in the third segment of the tripartite leader. A polypeptide with the same molecular weight as predicted from the DNA sequence was identified by in vitro translation of mRNA which had been selected by hybridization to DNA fragments, containing sequences from the i-leader. The results thus suggest that the i-leader, unlike other adenovirus leader segments, is used for translation.

Adenoviruses, Human↗
PubMed1982

A novel mRNA and a low molecular weight polypeptide encoded in the transforming region of adenovirus DNA.

Immunoprecipitation was used to identify adenovirus type 2 (ad2) tumor antigens synthesized in vivo. The antisera, prepared from tumor-bearing animals, reacted with a wide spectrum of ad2 early proteins including a 11 000-dalton (11 K) polypeptide. The gene for this polypeptide was mapped to the transforming region of the viral genome by hybridization selection followed by in vitro translation and immunoprecipitation. Hybrid arrest translation revealed that the 11 K RNA was transcribed from the leftward reading strand (1-strand) in contrast to other mRNAs from this region. Sucrose gradient analysis of the selected 11 K mRNA revealed that the size of the mRNA was 20S corresponding to approximately 2000 nucleotides. Novel 1-strand transcripts of this length from the transforming region were identified by S1 endonuclease analysis. Taken together, these results suggest that both strands of the transforming region of ad2 DNA are actively transcribed into functional mRNA early after viral infection.

Adenoviruses, Human↗
PubMed1982

B-cell growth factor: distinction from T-cell growth factor and B-cell maturation factor.

A T-cell hybridoma was derived by somatic cell hybridization between concanavalin A-activated BALB/c spleen cells and the AKR thymoma BW 5147. Media conditioned by hybridoma cells, even at high dilutions (1:1,000) support the growth of lipopolysaccharide-stimulated B-cell blasts but not that of T-cell growth factor (TCGF)-reactive T-cells. This activity, herein designated B-cell growth factor (BCGF), has a Mr of approximately equal to 20,000 and it can readily be separated from TCGF (Mr approximately equal to 30,000) by gel filtration. BCGF is constitutively produced by the hybridoma cells, it is removed from conditioned media by incubation with target cells at +4 degrees C, and it is equally effective on B-cell blasts carrying different major histocompatibility complex and Ig haplotypes. BCGF shows no T-cell replacing factor (TRF) activity, and it is poor in supporting the development of Ig-secreting plaque-forming cells in B-cell blast cultures. Terminal maturation, however, can be induced in BCGF-dependent blasts by addition of conditioned media from normal helper T cell cultures, suggesting that two distinct factors are involved in the helper cell-dependent growth and maturation of B lymphocytes.

Animals↗
PubMed1982

Purification of a native membrane-associated adenovirus tumor antigen.

A 15,000-dalton protein was purified from HeLa cells infected with adenovirus type 2. Proteins solubilized from a membrane fraction of lytically infected cells was used as the starting material for purification. Subsequent purification steps involved lentil-lectin, phosphocellulose, hydroxyapatite, DEAE-cellulose, and aminohexyl-Sepharose chromatographies. A monospecific antiserum, raised against the purified protein, immunoprecipitated a 15,000-dalton protein encoded in early-region E1B (E1B/15K protein) of the adenovirus type 2 DNA. Tryptic finger print analysis revealed that the purified protein was identical to the E1B/15K protein encoded in the transforming part of the viral genome. The antiserum immunoprecipitated the E1B/15K protein from a variety of viral transformed cell lines isolated from humans, rats, or hamsters. The E1B/15K protein was associated with the membrane fraction of both lytically and virus-transformed cell lines and could only be released by detergent treatment. Furthermore, a 11,000- to 12,000-dalton protein that could be precipitated with the anti-E1B/15K serum was recovered from membranes treated with trypsin or proteinase K, suggesting that a major part of the E1B/15K protein is protected in membrane vesicles. Translation of early viral mRNA in a cell-free system, supplemented with rough microsomes, showed that this protein was associated with the membrane fraction also in vitro.

Adenoviruses, Human↗
PubMed1981

Controls of RNA splicing and termination in the major late adenovirus transcription unit.

The major late adenovirus promoter is active early after infection, selectively producing messenger RNAs coding for polypeptides with molecular weights of 55,000, 52,000 and 14,000. This selective expression suggests that a differential splicing pattern occurs at the transition from early to late viral gene expression. Activation of the late promoter and splicing of the 55, 52K mRNAs does not require newly synthesized virus polypeptides.

Adenoviruses, Human↗
PubMed1981

Adenovirus early gene products may control viral mRNA accumulation and translation in vivo.

The mechanisms controlling early adenovirus gene expression in vivo have been studied using inhibitors of protein synthesis. When inhibitors were added shortly before or at the onset of infection, viral mRNA from all early regions was transcribed, spliced and accumulated over a 7 hr period. After longer pretreatment, accumulation of several early mRNAs were suppressed. Addition of inhibitors 1 hr after infection enhanced the accumulation of viral mRNA in the cytoplasm. Translation of early mRNA selected on adenovirus DNA in a cell-free system reflected the amount of viral mRNA present. A viral coded product may therefore control accumulation of viral mRNA. A different pattern emerged when inhibitors of protein synthesis were removed at 5 hr postinfection and cells were removed at 5 hr postinfection and cells were pulse-labeled in vivo. If inhibitors were introduced at or before infection, early viral proteins were synthesized only after a lag of 1-3 hr. However, if treatment was introduced 1 hr postinfection, reversion of the protein synthesis block was instantaneous. It appears that protein synthesis inhibitors reveal an in vivo translational block for viral mRNA. This block could be overcome by preinfection with a related virus. Furthermore, no block was observed in a virus-transformed human embryonic kidney cell line (293) which expresses early region 1 of the viral genome. Viral gene product(s) encoded in early region 1 may control translation of early adenovirus messenger RNA in vivo.

Adenoviruses, Human↗
PubMed1981

A study of 136 cases of adder bite treated in Swedish hospitals during one year.

The adder (Vipera verus) is the only naturally occurring poisonous snake in Sweden. During one year, 136 patients were hospitalized due to adder bites in a population of 5.3 mill. (63% of the total population). These patients could be traced through the central register on diagnosis codes and have been studied retrospectively. The main purpose of the investigation was to study the epidemiology and to estimate the degree of poisoning, thereby getting an idea of the frequency of really severe cases. Minor local symptoms occurred in 27% of the patients, whereas 46% suffered mild, 15% moderate and 12% severe poisonings. The average duration of hospitalization was 1.6, 3.8, 5.5 and 7.6 days, respectively, for these four groups. Shock, CNS disturbances, anaphylactic reactions, extensive edemas, renal dysfunction and severe anemia were typical findings in the group with severe reactions. Although no deaths occurred, the proportion of severe cases contrasts with the current conception that severe envenomation after adder bites is rare. The mortality due to adder bite has been low during the last decades. Earlier the situation was different, and during 1911-78 altogether 44 deaths due to adder bite were registered in Sweden.

Adolescent↗
PubMed1981

Gene and mRNA for precursor polypeptide VI from adenovirus type 2.

We present a 1,040-base-pair-long sequences of adenoviruses type 2 DNA which encodes the complete gene for precursor polypeptide VI (pVI). pVI consists of 250 amino acids amounting to a molecular weight of 26,990. The proteolytic cleavage maturing pVI to virion polypeptide VI removes 33 amino acids from the amino-terminal end of the polypeptide, thus giving the mature polypeptide VI a molecular weight of 23,400. The UAA stop codon terminating pVI translation is separated by 84 nucleotides from the initiator triplet for the hexon gene. Both polypeptides are encoded by the same translational reading frame, suggesting the evolution of pVI and hexon as separate proteins by the introduction of a termination codon and selection of a new splice acceptor site in an ancestral fused polypeptide chain. The splice site where the common tripartite leader is attached to the pVI mRNA precedes the initiator codon for pVI translation by one nucleotide and forms, together with other late splice acceptor sites, a late adenovirus consensus acceptor site. We also demonstrate that the 3' end of the mRNA's belonging to the L2 3'-cotermination family is located only 31 nucleotides upstream from the splice junction of the pVI mRNA. Furthermore, we show that four novel polypeptides of molecular weights 80,000, 39,000, 36,000, and 10,500 are encoded by region L2.

Adenoviruses, Human↗
PubMed1981

Control of adenovirus early gene expression: accumulation of viral mRNA after infection of transformed cells.

We studied the accumulation of viral mRNA in the presence of inhibitors of protein synthesis in an adenovirus type 5-transformed cell line (line 293 cells). An analysis of the endogenous viral mRNA's and proteins revealed that only early regions 1A and 1B were expressed in uninfected 293 cells. However, viral mRNA's from early regions 2, 3, and 4, as well as mRNA's from early regions 1A and 1B, accumulated in 293 cells after infection with adenovirus type 2. Cells treated with anisomycin before infection showed a drastic enhancement of mRNA from early region 4 compared with drug-free controls, This increase in viral mRNA was detected by using filter hybridization, S1 endonuclease mapping, and in vitro translation. The rate of transcription of early region 4 nuclear RNA also increased significantly in the presence of anisomycin. In contrast to the results with early region 4, the levels of cytoplasmic mRNA's from early regions 2 and 3 did not increase in cells treated with inhibitors. These results suggested that multiple virus encoded controls operate on the early regions of the adenovirus genome.

Adenoviruses, Human↗
PubMed1981

Control of adenovirus early gene expression: posttranscriptional control mediated by both viral and cellular gene products.

An adenovirus type 5 host range mutant (hr-1) located in region E1A and phenotypically defective in expressing viral messenger ribonucleic acid (RNA) from other early regions (Berk et al., Cell 17:935-944, 1979) was analyzed for accumulation of viral RNA in the presence of protein synthesis inhibitors. Nuclear RNA was transcribed from all early regions at the same rate, regardless of whether the drug was present or absent. As expected, low or undetectable levels of RNA were found in the cytoplasm of hr-1-infected cells compared with the wild-type adenovirus type 5 in the absence of drug. When anisomycin was added 30 min before hr-1 infection, cytoplasmic RNA was abundant from early regions E3 and E4 when assayed by filter hybridization. In accordance, early regions E3 and E4 viral messenger RNA species were detected by the S1 endonuclease mapping technique only in hr-1-infected cells that were treated with the drug. Similar results were obtained by in vitro translation studies. Together, these results suggest that this adenovirus type 5 mutant lacks a viral gene product necessary for accumulation of viral messenger RNA, but not for transcription. It is proposed that a cellular gene product serves as a negative regulator of viral messenger RNA accumulation at the posttranscriptional level.

Adenoviridae↗
PubMed1980

Multiple mRNA species for the precursor to an adenovirus-encoded glycoprotein: identification and structure of the signal sequence.

Early region 3 of the adenovirus type 2 genome encodes three proteins with molecular weights of 16,000, 14,500, and 14,000 (E2/16, E3/14.5, and E3/14). The E3/16 protein is the precursor to the E3/19 glycoprotein and is around 1500 daltons larger than the unglycosylated E3/19O protein. The E3/14.5 and E3/14 proteins are structurally related to each other but different from E3/16. Three mRNA species were identified for E3/16; all have common 5' ends with the same spliced region but with different 3' ends. E3/14 was translated from a 13S mRNA with the same 5' structure as the E3/16 mRNA but followed by a second spliced region with a different 3' end. A partial amino acid sequence was determined for E3/16 after radioactive labeling in vitro and this sequence can be aligned with a known DNA sequence. It contains a hydrophobic signal sequence, two presumptive glycosylation sites, and a hydrophobic region close to the COOH terminus.

Adenoviruses, Human↗