PubMed Health⌕ Search

Biomedical subjects

V Romanowski

Publications and source records attributed to V Romanowski.

At least 19 recordsLinked to original sources
PubMed2001

Arenavirus nucleocapsid protein displays a transcriptional antitermination activity in vivo.

RNA polymerase pausing and transcriptional antitermination regulates gene activity in several systems. In arenavirus infected cells the switch from transcription to replication is subjected to a hairpin-dependent termination and requires protein synthesis to bypass this signal. The transcriptional antitermination control by Junín virus nucleocapsid protein N, has been demonstrated in vivo by infecting BHK-21 cells expressing this viral protein in the presence of translation inhibitors. This is the first demonstration in vivo of a transcriptional antitermination control in arenavirus-infected cells.

Animals↗
PubMed2001

Generation of a recombinant Anticarsia gemmatalis multicapsid nucleopolyhedrovirus expressing a foreign gene under the control of a very late promoter.

A recombinant Anticarsia gemmatalis multicapsid nucleopolyhedrovirus (AgMNPV) expressing beta-galactosidase under the control of the polyhedrin promoter was generated in our laboratory. To this end, we cloned the AgMNPV-2D genomic DNA fragment containing the polh gene and subcloned and sequenced the polyhedrin gene and its flanking regions. Based on this sequence information, sets of primers were designed to amplify the flanking regions by PCR, including appropriate restriction sites. The transfer vector (pAgPHZ) was constructed by the consecutive cloning of these PCR fragments flanking the Escherichia coli LacZ gene, in place of the polh gene. pAgPHZ was used for cotransfection of UFL-AG-286 insect cells with AgMNPV-2D DNA and the required recombinant, generated by homologous recombination with the polh locus, was identified by its polh(-)/LacZ+ plaque phenotype. Its genome structure was confirmed by PCR, restriction digestion and Southern blot analyses. The kinetics and levels of expression of beta-galactosidase in UFL-AG-286 cells infected with the recombinant were tested by SDS-PAGE and enzymatic activity assays.

Animals↗
PubMed2001

Characterization of a granulovirus isolated from Epinotia aporema Wals. (Lepidoptera: Tortricidae) larvae.

A granulovirus (GV) isolated from Epinotia aporema (Lepidoptera: Tortricidae)-a major soybean pest-was studied in terms of its main morphological, biochemical, and biological properties. The ovoidal occlusion bodies were 466 by 296 nm in size, and their most prominent protein had an apparent molecular mass of 29 kDa. Its amino-terminal sequence was remarkably homologous to that of the granulins of other GVs. The DNA genome size was estimated to be 120 kbp. The high specificity and pathogenicity of this newly described granulovirus (EpapGV) indicate that it is indeed a good candidate for the biological control of this pest.

Amino Acid Sequence↗
PubMed2001

In vitro and in vivo herpetic vector-mediated gene transfer in the pituitary gland: impact on hormone secretion.

OBJECTIVE: Herpes simplex virus type 1 (HSV-1)-derived vectors are known to be effective tools to deliver transgenes into normal and neoplastic anterior pituitary (AP) cells in vitro. Our objective was to assess the in vitro and in vivo effects of tsK/beta-gal, a temperature-sensitive HSV-1-derived vector harbouring the E. coli beta-galactosidase gene, on AP hormone secretion as well as on transgene expression in rat AP tumours (hyperplastic prolactinomas). DESIGN: The impact of vector infection on prolactin (PRL) and GH release was determined in vitro in normal and hyperplastic (lactotrophic) dispersed AP cells exposed for 24 h to tsK/beta-gal as well as in vivo in ectopic AP grafts. In some oestrogen-induced prolactinoma-carrying rats, vector suspension was stereotaxically injected into the glands to assess transgene expression in vivo. METHODS: GH and PRL release was measured by specific RIAs. In vivo transgene expression was assessed by immunohistochemistry for beta-galactosidase and enzymohistochemistry (5-bromo-4-chloro-3-indolyl-beta-d-galactopyranoside). Ectopic pituitary grafts and stereotaxic surgery were performed following standard procedures. RESULTS: At a multiplicity of infection of 0.5, the vector induced a 30 and 22% fall in PRL and GH release respectively in normal AP cells, whereas the corresponding hormone release inhibition for hyperplastic AP cells was 41 and 33% for PRL and GH respectively. In ectopic pituitary grafts, the effect of vector infection on hormone secretion was assessed by measuring serum PRL levels in the host rats every 5 days for 4 weeks post-grafting. In the pituitary-grafted rats that received the viral vector, serum PRL failed to increase to the levels achieved in control-grafted animals. Finally, pituitary tumours stereotaxically injected with tsK/beta-gal showed widespread expression of the beta-galactosidase transgene around the injection areas. CONCLUSIONS: The results reported here have implications for basic studies using gene transfer to pituitary gland as well as potential gene therapy approaches to pituitary diseases.

Animals↗
PubMed2000

DNA fingerprinting of thermophilic lactic acid bacteria using repetitive sequence-based polymerase chain reaction.

DNA fingerprints of lactic acid bacteria were generated by polymerase chain reaction using a primer based on the repetitive elements found in the genome of Streptococcus pneumoniae (BOX-PCR). The method made it possible to identify 37 isolates from raw milk. industrial starters and yogurt. Differentiation at species, subspecies and strain level was possible for Lactobacillus delbrueckii subsp. lactis, Lb. delbrueckii subsp bulgaricus and Str. thermophilus. BOX-PCR was also applied to studying the strain composition of a starter culture and the direct detection of strains in commercial fermented milk.

Animals↗
PubMed1998

Arenavirus phylogeny: a new insight.

Arenaviridae is a worldwide distributed family, of enveloped, single stranded, RNA viruses. The arenaviruses were divided in two major groups (Old World and New World), based on serological properties and genetic data, as well as the geographic distribution. In this study the phylogenetic relationship among the members of the Arenaviridae was examined, using the reported genomic sequences. The comparison of the aligned nucleotide sequences of the S RNA and the predicted amino acid sequences of the GPC and N proteins, together with the phylogenetic analysis, strongly suggest a possible kinship of Pichindé and Oliveros viruses, with the Old World arenavirus group. This analysis points at the evolutive relationships between the arenaviruses of the Americas and can be used to evaluate the different hypotheses about their origin.

Arenavirus↗
PubMed1997

Characterization of arenaviruses using a family-specific primer set for RT-PCR amplification and RFLP analysis. Its potential use for detection of uncharacterized arenaviruses.

Arenaviruses are enveloped viruses with a genome composed of two ssRNA species, designated L and S. The arenaviruses were divided in two major groups (Old World and New World), based on serological properties and genetic data, as well as geographic distribution. A sequence alignment analysis of all reported arenavirus S RNAs yielded 17 conserved regions in addition to a reported conserved region at the end of both RNAs. The consensus sequences of these regions were used to design generalized primers suitable for RT-PCR amplification of a set of overlapping nucleotide sequence fragments comprising the complete S RNA of any arenavirus. A restriction analysis (RFLP) was designed to rapidly typify the amplified fragments. This RT-PCR-RFLP approach was tested with Old World (LCM) and New World (Junin and Tacaribe) arenaviruses. Furthermore, using this procedure the whole S RNA of a novel arenavirus isolate obtained from a rodent trapped in central Argentina, was amplified and characterized. Partial nucleotide sequence data were used for phylogenetic analyses that showed the relationships between this arenavirus and the rest of the members of the family. This relatively simple methodology will be useful both in basic studies and epidemiological survey programs.

Animals↗
PubMed1997

Molecular characterization of attenuated Junin virus strains.

The Junin virus strain Candid #1 was developed as a live attenuated vaccine for Argentine haemorrhagic fever. In this paper we report the nucleotide sequences of S RNA of Candid #1 and its more virulent ancestors XJ#44 and XJ (prototype). Their relationship to Junin virus wild-type MC2 strain and other closely and distantly related arenaviruses was also examined. Comparisons of the nucleotide and amino acid sequences of N and GPC genes from Candid #1 and its progenitor strains revealed some changes that are unique to the vaccine strain. These changes could be provisionally associated with the attenuated phenotype.

Amino Acid Sequence↗
PubMed1997

The glycoprotein precursor gene of the attenuated Junin virus vaccine strain (Candid #1).

A live attenuated virus vaccine has been recently developed to prevent Argentine hemorrhagic fever. In this paper, we report the nucleotide sequence of the glycoprotein precursor gene (GPC) of the Junin virus vaccine strain (Candid #1) and its flanking untranslated regions. The untranslated regions flanking the GPC genes of different arenaviruses are variable in length, sequence, and secondary structure. However, when this highly attenuated Junin virus strain is compared with the MC2 strain, which is of intermediate virulence, one nucleotide insertion and four nucleotide substitutions are found at positions that do not affect the predicted secondary structure. When Candid #1 and MC2 RNAs are compared, the nucleotide sequence changes in the GPC open reading frame are concentrated in the amino-proximal and the carboxy-proximal regions. The comparison of the amino acid residues shows that the major changes are located in the amino-proximal region of the GPC.

Amino Acid Sequence↗
PubMed1996

Computational characterisation of potential RNA-binding sites in arenavirus nucleocapsid proteins.

A nucleocapsid protein of an RNA virus was characterised using computational methods. Similarity searches using standard algorithms and more sensitive methods based on profiles were performed. Also, secondary structure prediction and statistical methods were used. The results show that the protein belongs to a unique well-characterised family, with three regions with potential RNA binding capacity. The amino-terminal region is found to contain a mixed-charge segment similar to proteins that bear nucleic acid-protein interaction capacity. The middle-region has a slight homology to the nucleolar protein Fibrillarin containing an atypical RNP-1 conserved octamer. Finally, the carboxyl-terminal region has a putative zinc-finger.

Algorithms↗
PubMed1996

PCR screening for carriers of bovine leukocyte adhesion deficiency (BLAD) and uridine monophosphate synthase (DUMPS) in Argentine Holstein cattle.

BLAD (Bovine Leukocyte Adhesion Deficiency) and DUMPS (Deficiency of Uridine Monophosphate Synthase) are monogenic autosomal, recessive inherited diseases of Holstein cattle. Single nucleotide changes (point mutations) responsible for the genetic disorders were detected by polymerase chain reaction coupled with restriction fragment length polymorphism assays (PCR-RFLP). Using oligonucleotide primers, DNA fragments of predicted sizes were amplified, and the products' specificity was assessed by nucleotide sequencing. Mutations were detected in DNA samples from bovine blood and semen by the presence or absence of restriction sites within the PCR amplification products (Taq I, Hae III for BLAD, Ava I for DUMPS). The test included 104 bulls and 950 cows of Argentinean Holstein breed. Defective alleles frequencies were as follows: 2.88% BLAD in bulls used in artificial insemination, 1.79% in cows; 0.96% DUMPS in bulls and 0.11% in cows.

Animals↗
PubMed1995

Rapid diagnosis of Argentine hemorrhagic fever by reverse transcriptase PCR-based assay.

Argentine hemorrhagic fever (AHF) is an endemo-epidemic disease caused by Junín virus. This report demonstrates that a reverse transcriptase (RT) PCR-based assay developed in our laboratory to detect Junín virus in whole blood samples is sensitive and specific. The experiments were conducted in a double-blinded manner using 94 clinical samples collected in the area in which AHF is endemic. The RT-PCR-based assay was compared with traditional methodologies, including enzyme-linked immunosorbent assay, plaque neutralization tests, and occasionally viral isolation. The calculated parameters for RT-PCR diagnosis, with seroconversion as the "gold standard," were 98% sensitivity and 76% specificity. It is noteworthy that 94% of the patients with putative false-positive results (RT-PCR positive and no seroconversion detected) exhibited febrile syndromes of undefined etiology. These results could be interpreted to mean that most of those patients with febrile syndromes were actually infected with Junín virus but did not develop a detectable immune response. Furthermore, 8 laboratory-fabricated samples and 25 blood samples of patients outside the area in which AHF is endemic tested in a similar way were disclosed correctly (100% match). The RT-PCR assay is the only laboratory test available currently for the early and rapid diagnosis of AHF. It is sensitive enough to detect the low viremia found during the period in which immune plasma therapy can be used effectively, reducing mortality rates from 30% to less than 1%.

Argentina↗
PubMed1994

Phenol extraction revisited: a rapid method for the isolation and preservation of human genomic DNA from whole blood.

We report a fast and simple DNA isolation method from whole blood. It avoids cell separation and lysis steps and consists of three successive solvent extractions and an ethanol precipitation. All the steps are carried out at room temperature. The main advantage of this method is the immediate sample inactivation achieved by mixing the blood sample with Tris-HCl (pH 8.0) saturated phenol, thus minimizing the biohazard involved in the subsequent manipulation of the samples potentially contaminated with infectious agents (the procedure has been called SP for 'straight phenol'). In addition, extensive field sample collections are facilitated by the fact that the SP procedure can be stopped right after the simple manipulation of mixing the blood sample with the phenol; neither freezing nor refrigeration of the sample proved to be required. At this stage, the nucleases as well as infectious agent are inactivated and the rest of the protocol can wait to be carried out in the laboratory. In fact, the DNA preparation can be resumed after prolonged storage of the blood-phenol mix (up to 72 days has been checked in our laboratory) at room temperature without affecting the yield. The SP protocol may be scaled up, when large quantities of DNA are needed, or scaled down to smaller volumes, such as fingerprick blood samples.

Base Sequence↗
PubMed1993

A simple nucleic acid amplification assay for the rapid detection of Junín virus in whole blood samples.

Argentine hemorrhagic fever (AHF) is an endemoepidemic disease with cardiovascular, renal and neurologic alterations acquired in the richest farming land in Argentina. It is caused by Junín virus, one of the few human pathogenic arenaviruses. The S RNA of Junín virus has been molecularly cloned and its nucleotide sequence determined in our laboratory. This information was used to develop a rapid nucleic acid-based diagnostic test commensurate with the low viraemia detected in AHF patients. Junín virus-specific cDNA probes labeled using various methods proved insensitive in dot-hybridizations. Therefore, a RT polymerase chain reaction (PCR) was developed using a pair of oligonucleotide primers to reverse-transcribe and amplify the viral S RNA. The amplification of the target sequences was measured by ethidium bromide staining of the DNA fragments after agarose gel electrophoresis. This type of assay allowed the specific detection of Junín virus RNA sequences present in a single infected BHK21 cell over a background of 10(4) uninfected cells. Control reactions were performed on RNA samples extracted from uninfected cells or cells infected with a high multiplicity of LCMV, another arenavirus present in the AHF endemic area. The PCR was first adapted to detect viral RNA in peripheral blood mononuclear cells, described to harbor most of the virus. A simplification of this assay allows the detection of Junín virus in RNA extracted from 100 microliters of whole blood using guanidium thiocyanate disruption and acid phenol extraction. Under the conditions described in this paper, it is possible to detect up to 0.01 pfu of Junín virus in a blood sample. An early and rapid laboratory diagnostic test for AHF is important since the only effective therapy that reduces the mortality rate from 30% to less than 1% consists of early treatment with immune plasma.

Animals↗
PubMed1991

Molecular organization of Junin virus S RNA: complete nucleotide sequence, relationship with other members of the Arenaviridae and unusual secondary structures.

In this study, overlapping cDNA clones covering the entire S RNA molecule of Junin virus, an arenavirus that causes Argentine haemorrhagic fever, were generated. The complete sequence of this 3400 nucleotide RNA was determined using the dideoxynucleotide chain termination method. The nucleocapsid protein (N) and the glycoprotein precursor (GPC) genes were identified as two non-overlapping open reading frames of opposite polarity, encoding primary translation products of 564 and 481 amino acids, respectively. Intracellular processing of the latter yields the glycoproteins found in the viral envelope. Comparison of the Junin virus N protein with the homologous proteins of other arenaviruses indicated that amino acid sequences are conserved, the identity ranging from 46 to 76%. The N-terminal half of GPC exhibits an even higher degree of conservation (54 to 82%), whereas the C-terminal half is less conserved (21 to 50%). In all comparisons the highest level of amino acid sequence identity was seen when Junin virus and Tacaribe virus sequences were aligned. The nucleotide sequence at the 5' end of Junin virus S RNA is not identical to that determined of the other sequenced arenaviruses. However, it is complementary to the 3'-terminal sequences and may form a very stable panhandle structure (delta G-242.7 kJ/mol) involving the complete non-coding regions upstream from both the N and GPC genes. In addition, a distinct secondary structure was identified in the intergenic region, downstream from the coding sequences; Junin virus S RNA shows a potential secondary structure consisting of two hairpin loops (delta G -163.2 and -239.3 kJ/mol) instead of the single hairpin loop that is usually found in other arenaviruses. The analysis of the arenavirus S RNA nucleotide sequences and their encoded products is discussed in relation to structure and function.

Amino Acid Sequence↗
PubMed1991

Patterns of transient expression of the arenavirus nucleocapsid protein gene in transfected cells.

The cloned genes for the nucleocapsid proteins N of Junín and LCM (lymphocytic choriomeningitis) arenaviruses were inserted into the SV40-derived expression vector designated pKG4. When BHK-21 (baby hamster kidney fibroblasts) and CV-1 (African green monkey kidney fibroblasts) cell lines were transfected using these constructions, the transient expression yielded a polypeptide that could not be distinguished either by size nor by immunoreactivity from the N protein synthesized during the viral infection. The immunofluorescence analysis showed a pattern of intracellular localization similar to that observed in virus infected cells, i.e. varying from a diffuse cytoplasmic staining to granules, either distributed throughout the cytoplasm or concentrated in the perinuclear region. The association of the N protein with basophilic granules is similar to that observed in the cytopathic effect caused by arenaviruses, and could be related to the physicochemical properties of this polypeptide containing numerous basic amino acid sequences, that would allow for the interaction with cellular RNAs.

Animals↗