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M Valassina

Publications and source records attributed to M Valassina.

32 records · Page 2Linked to original sources
PubMed1999

Helicobacter pylori determinants of pathogenicity.

The bacterium Helicobacter pylori colonises the stomach of man and induces a strong inflammatory response. Differences in the possession of pathogenicity determinants by H. pylori isolates could account in part for the different clinical outcomes of infection. The main H. pylori pathogenic factors, i.e. urease, the cytotoxin VacA, and the genes involved in virulence contained in the pathogenicity island (PAI) cag, may promote tissue damage and ulceration, and could contribute to gastric cancer development. Strains with the mosaic vacA allelic type s1a/m1 and possessing the cag insertion are considered endowed with increased inflammatory potential, and are more likely to be isolated from patients with peptic ulcer and gastric cancer. The presence in H. pylori cag PAI of operons involved in the stimulation of gastric epithelial cells to secrete high levels of inflammatory cytokines, in mobilisation of DNA, and formation of secretory mechanisms and conjugation apparati, could contribute to increase the risk of gastric cancer development in patients infected by this microorganism.

Bacterial Outer Membrane Proteins↗
PubMed1999

Peripheral neuropathy associated with anti-myelin basic protein antibodies in a woman vaccinated with rubella virus vaccine.

Active immunisation with rubella vaccine has not been commonly associated with neurological complications. We report the case of a 23-year-old woman who developed a mild, distal demyelinating neuropathy after immunisation with the live attenuated RA 27/3 rubella strain. Post-immunisation immunologic studies carried over 24 months showed the presence of antibodies to the RV proteins, particularly to the capsid antigen, and to the myelin basic protein (MBP). A similarity between a C antigen motif and a sequence of the MBP was found by computer analysis. The cross-reactivity was confirmed by immunising mice with a synthetic peptide derived from the MBP, which developed a strong humoral response to RV and MBP. This finding raises the possibility that a virus-induced immune response could lead to an autoaggressive reaction responsible for demyelination.

Adult↗
PubMed1998

Diagnostic potential of Toscana virus N protein expressed in Escherichia coli.

The nucleocapsid (N) protein of the Toscana (TOS) virus was expressed in Escherichia coli by using a pET15b vector. The recombinant protein was purified by affinity chromatography and was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblotting, and enzyme immunoassay (EIA). The recombinant antigen was reactive with positive human sera, and the reactivity correlated very well (r = 0.9) with that of a whole-virus antigen when tested by EIA with 30 TOS virus-positive and 30 TOS virus-negative serum samples. The results demonstrate that the recombinant N protein can be easily produced in a procaryotic system and used for diagnostic assays for TOS virus immunity.

Antibodies, Viral↗
PubMed1997

Rapid detection of different RNA respiratory virus species by multiplex RT-PCR: application to clinical specimens.

BACKGROUND: The polymerase chain reaction (PCR) applied in diagnostic and epidemiologic investigations is very useful for sensitivity, specificity and time saving. OBJECTIVE: We have developed a method for the detection of genomic RNA of two different species of virus, the influenza A virus (IA) and the respiratory syncytial virus (RS), which are responsible for clinical similarities. We applied this multiplex RT-PCR protocol on clinical specimens. STUDY DESIGN: We describe a method which allows rapid diagnosis by performing a single retro-transcriptase (RT) reaction associated with the PCR (multiplex RT-PCR) on different genomes in a single sample. We have evaluated the sensitivity and the specificity of the multiplex test on positive controls, then, on RNA extracted from clinical specimens harvested from 15 children with respiratory symptoms during the spring-winter season 1997. RESULTS AND CONCLUSIONS: The multiplex RT-PCR protocol, applied to respiratory specimens, allows the investigation of RNA IA virus and RS virus in a single sample at the same time. The detection of the etiologic viral agent is rapid and it is possible to evaluate incidental simultaneous infections.

Animals↗
PubMed1996

Rapid identification of Toscana virus by nested PCR during an outbreak in the Siena area of Italy.

The sand fly-transmitted Toscana virus is recognized as an etiologic agent of an aseptic meningitis with a long convalescence. This infection has been reported overall in many tourists or in a seronegative population circulating in endemic Mediterranean areas (Italy, Portugal, Egypt, and Cyprus). We report a cluster of acute Toscana virus infections in the local population during the summer of 1995. Twenty-one clinical cases of meningitis were investigated for the presence of Toscana virus by nested PCR performed on the S segment of the virus RNA extracted from cerebrospinal fluid samples.

Adolescent↗
PubMed1995

Detection by multiplex polymerase chain reaction and typing of Chlamydia trachomatis isolates.

The multiplex polymerase chain reaction (PCR) was applied for the detection of the Chlamydia trachomatis chromosome and plasmid. The multiplex PCR demonstrated a sensitivity of 0.8 fg of chlamydial DNA, corresponding to the detection of about 5 copies of the plasmid. Analysis of 195 genital specimens collected randomly from a female population, showed that the multiplex PCR is more sensitive and rapid than culturing for detecting Chlamydia trachomatis. Moreover, sequencing of the II variable domain of the omp1 gene, directly from DNA of the clinical specimens, appears to be a simple and rapid method for determining serovar isolates.

Bacterial Typing Techniques↗
PubMed1995

Evaluation of rubella virus E2 and C proteins in protection against rubella virus in a mouse model.

An animal model is described that can provide further information for evaluating novel vaccines against rubella virus (RV). A group of mice was immunized with the lysate of insect cells infected by a recombinant baculovirus expressing E2 and C proteins of RV. Another group of mice was immunized with the RA27/3 rubella vaccine. After 2 weeks, both groups of mice were challenged intramuscularly with live RV and the blood was drawn after 8, 24, 48 and 72 h. The presence of rubella challenge virus in an unnatural host, such as the mouse, was monitored by RT-PCR. The mice immunized with the RA27/3 rubella vaccine were the only ones able to inhibit the challenge virus replication, E2 and C proteins, which alone are not sufficient to protect animals against RV, served as a negative control for a protective vaccine against RV that expresses E1 protein of RV.

Animals↗
PubMed1989

Live-cell immunofluorescence for detection of human immunodeficiency virus type 1 (HIV-1)-related antigens in peripheral blood mononuclear cells from HIV-1 seropositive individuals.

Live-cell indirect immunofluorescence was used to detect HIV-associated antigens in fresh uncultured peripheral blood mononuclear cells from 29 HIV-seropositive subjects. Conventional fixed-cell immunofluorescence and live-cell immunofluorescence were run in parallel on each sample using monoclonal antibodies directed against HIV gag and env gene products. Sera from the same patients were also tested for HIV antigen by a sandwich enzyme immunoassay. Results strongly indicate that nondenaturing live-cell immunofluorescence is much more sensitive for detection of HIV-associated antigens and may be useful in the diagnosis of HIV infection as well as in the study of pathogenesis.

Antibodies, Monoclonal↗
PubMedDate not supplied

Rapid detection and typing of circulating mumps virus by reverse transcription/polymerase chain reaction.

The reverse transcription/polymerase chain reaction (RT-PCR) was used to amplify a 129-bp fragment of the mumps virus F gene from strains circulating in the Siena area from 1993-1995. The nucleic acid was amplified directly from the samples; no growth in cell culture was required. Nucleotide sequence analysis and the comparison with other virus strains enabled the typing of the detected viruses. There appears to be more than one lineage of mumps virus circulating at any given time in the same location. A PCR assay coupled with the sequencing of the 5' end of the F gene seems to be a convenient method for characterizing mumps virus strains. This method, useful in diagnosis, also appears to be suitable for epidemiological studies.

Adolescent↗