Biomedical subjects

M Waris

Publications and source records attributed to M Waris.

30 records · Page 2Linked to original sources

PubMed1995

Incidence of acute otitis media associated with group A and B respiratory syncytial virus infections.

The comparative association of respiratory syncytial virus group A and B infections with acute otitis media was determined by analysing the hospital records of children with community-acquired respiratory syncytial virus infection during three successive outbreaks from 1987 to 1992. Of 326 episodes analysed, 192 (59%) were caused by group A and 134 (41%) by group B infections. Acute otitis media was diagnosed in 101 (75%) children with group B infection, compared with 119 (62%) with group A infection (p = 0.01). Group A infections were more often associated with wheezing (71% versus 59% in group B; p = 0.02) and oxygen therapy in inpatients (48% versus 31%, respectively; p = 0.008). The higher incidence of acute otitis media associated with group B infections was observed both after adjustment for potential confounding variables and during each outbreak.

Acute Disease↗

PubMed1994

Linear antigenic and immunogenic regions of the respiratory syncytial virus P protein.

Three linear antigenic regions on the P protein from human respiratory syncytial virus (RSV) subgroup A (strain A2) were represented by peptides that reacted with monoclonal antibodies and with sera from humans with recent or previous RSV infection. The determinants were localized within three hydrophilic regions of the P protein: Pro91 to Asp110, Ser161 to Lys180 and Glu221 to Phe241. The role of individual amino acids in the epitopes defined by monoclonal antibodies was determined. Two monoclonal antibodies reacting with the same antigenic site were found to detect epitopes that had different amino acid dependencies. Rabbit hyperimmune sera raised against selected peptides specifically precipitated different forms of the P protein from RSV-infected 35S-labelled cell extracts in a radioimmune precipitation assay. These findings have implications for forthcoming structural-functional studies of RSV capsid component interactions and also for serological diagnosis of RSV infection.

Amino Acid Sequence↗

PubMed1992

Shedding of infectious virus and virus antigen during acute infection with respiratory syncytial virus.

Shedding of respiratory syncytial virus (RSV) in nasopharyngeal aspirates (NPA) of hospitalized children with acute respiratory infection was studied using direct antigen detection by time-resolved fluoroimmunoassay, rapid identification of infectious virus in centrifugally inoculated cell cultures by immunoperoxidase staining and conventional virus culture. Sequential NPAs, in which also local RSV-specific IgA response was measured, were collected from children with proven RSV infection. The shedding pattern was similar for both infectious virus and viral antigen. The overall agreement of the three methods was good (81%) in diagnostic specimens collected on admission, but markedly reduced (46%) in follow-up specimens. Secretory IgA was abundant in specimens giving discrepant or negative results only. The proportion of patients who shed RSV was high (> or = 87%) in the first week after onset of symptoms, and decreased sharply in the second week. An opposite temporal pattern was found in the proportion of patients with detectable RSV-IgA in their secretions. Sequentially isolated strains were antigenically stable as determined by their reactivity with a large panel of monoclonal antibodies. The findings suggest that RSV shedding should be monitored by using more than one method for virus detection.

Acute Disease↗

PubMed1992

Immunoglobulin G antibody avidity in patients with respiratory syncytial virus infection.

The titer and avidity of respiratory syncytial virus-specific antibodies were measured in 196 serum specimens from 93 children with an acute, laboratory-confirmed respiratory syncytial virus infection. An enzyme immunoassay method based on the ability of urea to dissociate the bound antibodies with low avidity from the antigen was used. Three patterns of immune responses were observed. Children less than 6 months of age usually had low titers of antibodies with high avidity in their acute-phase serum samples. These antibodies were concluded to be of maternal origin, since their reaction pattern was similar to that of healthy adults. During the next few weeks, a slight increase in titers with a concurrent decrease in antibody avidity was observed. All children 6 to 24 months of age had low-avidity antibodies in their acute-phase serum samples, which matured to high avidity during the follow-up. On the contrary, about half of the children greater than 24 months of age had high-avidity antibodies already in the acute-phase serum samples. We conclude that the former children were experiencing primary infections with respiratory syncytial virus and the latter were experiencing reinfections. All adults with remote immunity had antibodies with high avidity.

Adult↗

PubMed1991

Influenza vaccination in the prevention of acute otitis media in children.

We studied a new approach to the prevention of acute otitis media through the administration of influenza vaccine to 187 day-care center children aged 1 to 3 years before the influenza A epidemic of 1988-1989. The control group consisted of 187 unvaccinated children of similar age and background. During the 6-week study period, influenza A infection was diagnosed in five (3%) of 187 vaccinees and in 29 (16%) of 187 controls. Acute otitis media developed in three (60%) of five vaccinees with an influenza A infection compared with 18 (67%) of 27 controls (excluded were two children with a double viral infection). The incidence of acute otitis media associated with influenza A was reduced by 83% in the vaccinees. The total number of children with acute otitis media in the vaccine group was 35, compared with 55 in the control group, disclosing a 36% reduction among the vaccinees. We conclude that influenza vaccination decreases the incidence of acute otitis media in children during an influenza A epidemic, suggesting also that other vaccines against respiratory viruses may be an effective way to reduce the incidence of acute otitis media.

Causality↗

PubMed1991

Facile detection of anatoxin-a in algal material by thin-layer chromatography with Fast Black K salt.

A method for facile high-capacity screening of algal samples for anatoxin-a (ANTX-a), a potent neurotoxin of Anabaena flos-aquae, is presented. The method is based on in situ colour reaction of algal extracts containing ANTX-a on a thin-layer chromatographic plate with the diazonium reagent Fast Black K salt, and subsequent separation of the orange-red product. The product, shown to be a stable 3,3-dialkyltriazene, is derived from a reaction involving the aliphatic secondary amino group of ANTX-a. The detection limit for ANTX-a is 10 micrograms g-1 of lyophilized algal material, which is comparable to earlier methods using more complex instrumentation.

Bacterial Toxins↗

PubMed1991

Pattern of respiratory syncytial virus epidemics in Finland: two-year cycles with alternating prevalence of groups A and B.

Time-resolved fluoroimmunoassay with monoclonal antibodies distinguishing between respiratory syncytial virus (RSV) group A and B strains was used to analyze their prevalence in Finland during 1981-1990 among 3285 patients with laboratory diagnosis of RSV, most of them hospitalized. The group typing of antigens in 608 RSV-positive nasopharyngeal aspirates showed a regular alternation of group prevalence, following the cyclic occurrence of the virus. Group A predominated in 73%-90% of specimens from 1981-1982, 1985-1986, and 1989-1990, whereas group B predominated in 70%-100% of specimens from 1983-1984 and 1987-1988. The epidemiologic occurrence of verified reinfections in hospitalized children and the group typing results indicated that children greater than 6 months of age during the first infection were more resistant to severe reinfection with the homologous than with the heterologous group of virus. The study shows that group antigenic variation of RSV has a significant effect on the epidemiology of the virus.

Antibodies, Monoclonal↗

PubMed1990

Rapid detection of respiratory syncytial virus and influenza A virus in cell cultures by immunoperoxidase staining with monoclonal antibodies.

Peroxidase-labeled monoclonal antibodies against respiratory syncytial virus (RSV) and influenza A virus were used for immunoperoxidase staining (IPS) of cell cultures inoculated with nasopharyngeal aspirates. Cells were grown in 24-well plates, and specimens were inoculated by low-speed centrifugation. Cultures were incubated for 2 days at 37 degrees C and then fixed, stained, and observed by light microscopy. IPS was compared with standard virus isolation by using cultures of human diploid fibroblasts and Vero, HEp-2, and HeLa cell lines for RSV and Madin-Darby canine kidney cells for influenza A virus; these cultures were inoculated with specimens that were previously stored at -70 degrees C. Of 40 known RSV-positive specimens, 30 were found to be positive on reinoculation by both methods, and an additional 5 specimens were found to be positive by IPS only. Of 190 specimens tested for influenza A virus, 14 were positive by IPS and in tubes, and a further 8 specimens were positive by IPS only. IPS was also compared with direct detection of viral antigens in nasopharyngeal aspirates by a time-resolved fluoroimmunoassay (TR-FIA). Fresh nasopharyngeal aspirates were inoculated into human diploid fibroblasts and Madin-Darby canine kidney cells and tested for RSV and influenza A virus, respectively, by IPS. Of 110 specimens tested for RSV, 37 were positive in total, 32 were positive by IPS, and 33 were positive by TR-FIA. Of 150 specimens tested for influenza A virus, 39 were positive in total, 35 were positive by IPS, and 34 were positive by TR-FIA. IPS of cultures inoculated by centrifugation and incubated for 2 days is a sensitive method for the diagnosis of respiratory virus infections, and 24-well plates allow for the easy processing of a large number of specimens.

Animals↗

PubMed1989

One-incubation time-resolved fluoroimmunoassay based on monoclonal antibodies in detection of influenza A and B viruses directly in clinical specimens.

A new modified enzyme immunoassay screening method was developed for testing hybridoma cultures, so as to select antibodies useful for solid phase assays. Samples of hybridoma cultures were incubated for 1 h with purified nucleoprotein preparation in microtiter wells precoated with rabbit anti-influenza A or B immunoglobulin, followed by washing and addition of anti-mouse HRPO-conjugate. The monoclonal antibodies were then used in one-incubation time-resolved fluoroimmunoassay (TR-FIA) for detecting influenza viral proteins in nasopharyngeal aspirate specimens. The sample and europium (Eu)-labelled monoclonal detector antibody (100 microliter of each) were added simultaneously to microtiter wells precoated with anti-virus monoclonal antibody, and incubated for 1 h. After washing and addition of the enhancement solution the strips were shaken for 10 min before measurement of the fluorescence using a photon counting fluorometer. All of the monoclonal antibodies screened by our modified method and Eu-labelled worked as detector antibodies. Many of these monoclones also functioned as capture antibodies on solid phase. A total number of 309 (influenza A) and 104 (influenza B) nasopharyngeal aspirate specimens taken mainly from hospitalized children with acute respiratory disease were tested with the TR-FIA, using monoclonal antibodies produced by our modified screening method in comparison with monoclonal antibodies previously reported elsewhere (Walls et al., 1986). Results were similar, and superior to those obtained with routinely used indirect enzyme immunoassay based on polyclonal antibodies. The results of this study indicate that the one-incubation TR-FIA using monoclonal antibodies selected by the modified screening method is a highly sensitive and rapid method for detecting influenza A and influenza B virus in clinical specimens.

Antibodies, Monoclonal↗

PubMed1988

Herpes simplex virus detection by macroscopic reading after overnight incubation and immunoperoxidase staining.

Human diploid foreskin fibroblast cells grown in 24-well plates were inoculated with clinical specimens by centrifugation at 1,000 X g for 45 min. Cultures were incubated at 37 degrees C overnight, fixed, and stained with peroxidase-labeled monoclonal antibodies against herpes simplex virus types 1 and 2. Stained plaques of infected cells were large enough to be detected with the naked eye, and microscopic examination did not reveal any further positive specimens. The method was compared with standard isolation in human fibroblasts grown in shell vials and inoculated by centrifugation at 4,000 X g, observed microscopically for the occurrence of typical cytopathogenic effect three times a week for 10 days, and then typed by enzyme immunoassay. Of the 289 specimens tested, 105 were positive and 174 were negative by both methods. Six specimens were positive by standard isolation only, two of them containing varicella-zoster virus, and two specimens were stored frozen before being tested by immunoperoxidase staining. Two specimens found negative by standard isolation were positive by immunoperoxidase staining. For two specimens negative by immunoperoxidase staining, the standard isolation cultures were lost due to microbial contamination. Forty-two specimens found positive by standard isolation were clearly positive when stained only 8 h after inoculation. By standard isolation, positive results were reported on the average 3 to 4 days after inoculation, whereas by immunoperoxidase staining the result was available within less than 24 h. Immunoperoxidase staining of infected cells is a sensitive method for rapid laboratory diagnosis of herpes simplex virus infections, and 24-well plates are convenient for the handling of a large number of specimens.

Antibodies, Monoclonal↗

PubMed1988

Time-resolved fluoroimmunoassay compared with virus isolation for rapid detection of respiratory syncytial virus in nasopharyngeal aspirates.

Two monoclonal antibodies against two distinct conserved epitopes of the respiratory syncytial virus (RSV) nucleocapsid protein were used in a direct time-resolved fluoroimmunoassay (TR-FIA) for the detection of RSV antigens in nasopharyngeal aspirates. The capture antibody was adsorbed to the solid phase of microdilution strip wells, and the indicator antibody was labeled with a europium chelate. Specimens and label were incubated simultaneously for 1 h at 37 degrees C in the coated wells. After the test samples were washed, fluorescence enhancement solution was added, strips were shaken, and the time-resolved fluorescence was measured. The test procedure took only 75 min, and the total time for 20 specimens, with pretreatment by sonication, was 2 to 3 h. We prospectively evaluated the detection of RSV in nasopharyngeal aspirates of pediatric patients by TR-FIA and by virus isolation in human diploid fibroblasts. TR-FIA detected 40 of 42 isolation-positive specimens. Nine additional isolation-negative specimens were positive by TR-FIA; all proved to be true positives by a blocking-type confirmatory assay. The sensitivity, specificity, positive predictive value, and negative predictive value for TR-FIA were 95, 96, 82, and 99%, respectively, of the values obtained by virus isolation and 96, 100, 100, and 99%, respectively, of the values obtained by virus isolation and the confirmatory assay.

Adolescent↗

PubMed1987

Purification of adenovirus hexon protein by high-performance liquid chromatography.

Adenovirus (Type 2)-infected HeLa cells were sonicated and treated with 1,1,2-trichlorotrifluoroethane. The water-soluble extract was ultracentrifuged and the supernatant, containing the dissociated proteins, was subjected to anion-exchange high-performance liquid chromatography on a Mono Q column in 50 mM bis-Tris-HCl (pH 6.5). Elution with a linear salt gradient resulted in a major peak, containing the hexon protein.

Adenoviridae↗