Pekka Halonen

Herpes simplex encephalitis: A serological follow-up study: SYNTHESIS OF HERPES SIMPLEX VIRUS IMMUNOGLOBULIN M, A, AND G ANTIBODIES AND DEVELOPMENT OF OLIGOCLONAL IMMUNOGLOBULIN G IN THE CENTRAL NERVOUS SYSTEM

A solid‐phase radioimmunoassay method was used for the detection of herpes simplex virus (HSV) immunoglobulin M (IgM), IgA, and IgG antibodies within the central nervous system in 11 adult patients with acute HSV encephalitis. Serial cerebrospinal fluid (CSF) and serum specimens were sampled during the observation periods, extending up to 43 months after onset.

Rhinovirus in acute otitis media

Low positive results were somewhat easier to distinguish by EIA than LA, because the minimal color change produced in the EIA was more apparent than the few agglutinated latex particles in the LA test. However, some of the low positive Abbott Testpack Strep A and Cards Strep A plus and minus endpoints had an irregularly or partially filled vertical line that was neither clearly positive nor clearly negative, making interpretation difficult. The Icon Strep A tests resulted in the presence or absence of a clearly outlined central dot on a white background, giving unequivocal results, with only minimal experience required for interpretation.

Report of a Workshop on Respiratory Viral Infections: Epidemiology, Diagnosis, Treatment, and Prevention

Abstract An international workshop to review the epidemiology, diagnosis, treatment, and prevention of respiratory viral infections was held in Turku, Finland, in May 1991. This workshop emphasized the following points. (1) In epidemiological studies of influenza virus, serological, clinical, and gene-sequencing methods have been used to produce a full picture of genetic evolution. Less complete information exists about other viruses, although new data on respiratory syncytial virus are emerging. (2) Tools for the diagnosis of respiratory viral infections have been developed in conjunction with the use of solid-phase immunoassays. A role remains for tissue culture in surveillance and epidemiological studies. Detection of bacterial involvement in respiratory infections has been more difficult. (3) Treatment of infections due to respiratory viruses has advanced with the use of amantadine and aerosolized ribavirin. On the other hand, many viruses remain refractory to treatment. Means for preventing influenza are established, but barriers to the development of other viral vaccines—including the existence of multiple serotypes, imperfect natural immunity, and paradoxical hypersensitivity—have proven difficult to surmount.

A solid-phase radioimmunoassay for IgG and IgM antibodies against measles virus.

A solid-phase radioimmunoassay (RIA) was used to determine the presence of IgG and IgM antibodies to measles virus in human serum and cerebrospinal fluid (CSF). Purified measles virus was adsorbed on to polystyrene balls, which were then exposed to serial dilutions of test serum or CSF. The presence of antibody was measured by its capacity to bind 125I-labelled specific anti-human IgG or IgM. Serum from a variety of patients as well as measles-immune clinically healthy persons were tested; binding ratios (using negative human serum controls) were usually between 10 and 30, but with subacute sclerosing panencephalitis (SSPE) ratios were as high as 50. Of ten CSF specimens tested, all but one, which was taken early in the convalescent phase of measles infection, had detectable IgG antibody. In six patients with acute measles, IgM antibodies were found in all serum specimens taken one or more days after the onset of rash. Maximal titers of 1:10000 to 1:40000 were found about 7 days later. Thereafter, IgM titres decreased rapidly but were still detectable at 40 days. A purified ribonucleoprotein of measles virus was also used successfully as an antigen in this RIA method.

Detection of Viral Antigens by Time-Resolved Fluoroimmunoassay

Highly sensitive immunoassays have proved to be valuable in the diagnosis of viral infections because viral antigens can be directly detected in clinical specimens by these assays. This technology was first widely used in the radioimmunoassay of hepatitis B surface antigen in serum (Ling and Overby 1972) and later applied to the detection of gastroenteritis viruses in stool (Halonen and Meurman 1982). Our group has also developed assays for the detection of seven respiratory viruses in nasopharyngeal secretions (Sarkkinen et al. 1981a-c), and these assays have now been successfully applied on a routine basis in our diagnostic laboratory. Immuno-assays are now widely used in the detection of antiviral antibodies and particularly in the assay of IgM antibodies.

Type-specific detection of parainfluenza viruses by enzyme-immunoassay and radioimmunoassay in nasopharyngeal specimens of patients with acute respiratory disease.

A four-year solid phase enzyme-immunoassay (EIA) and radioimmunoassay (RIA) techniques were applied for the type-specific detection of parainfluenza type 1, 2 and 3 virus antigens in sonicated nasopharyngeal specimens of patients with acute respiratory disease. Guinea-pig antiviral immunoglobulins as the secondary antibodies, and horseradish peroxidase-labelled swine anti-rabbit immunoglobulins (EIA), or 125I-labelled sheep anti-rabbit IgG (RIA) as the indicator antibodies. A total of 174 nasopharyngeal specimens collected by mucus extractor were tested, and the results were compared with those obtained by a routinely used immunofluorescence (IF) technique. The same number of positive specimens were achieved by the EIA and the RIA and 3/4, 4/4, and 19/20 immunofluorescence (IF)-positive nasopharyngeal specimens were positive by the parainfluenza type 1, 2 and 3 immunoassays respectively. In addition, four parainfluenza type 1 and three parainfluenza type 3 virus-positive specimens were found by the immunoassays out of 146 parainfluenza IF-negative specimens. The type-specificities of the parainfluenza immunoassays were confirmed by showing that no cross-reactions occurred when purified immunizing antigens and the EIA- and RIA-positive clinical specimens were cross-tested. The results indicate that parainfluenza type-specific antigens can be detected directly in nasopharyngeal specimens by the immunoassays and the preliminary findings with a small number of positive specimens suggest that these assays have a diagnostic potential which is similar or slightly better than the IF techniques.

Viral Antibodies in the Sera from Patients with Parkinson Disease

An assay of antibodies to 15 various viruses and mycoplasma pneumoniae was performed on the serum specimens from 441 patients with Parkinson disease and from 443 healthy controls matched by sex, age, and place of residence, or from a representative group of these matched pairs. The main finding was a higher herpes simplex complement-fixing antibody level in patients with Parkinson disease than in controls. Patients with Parkinson disease had higher herpes simplex antibody titers more often than did their matched controls, and the matched controls, respectively, had low titers more often than the patients. The mean herpes simplex antibody titer (log2) of the patients (4.9) was significantly higher than that of controls (4.6) (p less than 0.01). This difference was also demonstrable when matched pairs were analysed for paired differences of herpes simplex antibody titers. For other viral CF and HI antibodies studied and for mycoplasma pneumoniae CF antibody, there were no significant differences either in the mean titers or in the distribution of individual titer values between the patients with Parkinson disease and the matched controls.

Measles Virus Antibody in Cerebrospinal Fluids from Patients with Multiple Sclerosis

A strong measles-specific gel precipitation reaction was found in the cerebrospinal fluid (C.S.F.) of two patients with multiple sclerosis (M.S.) (total of 15 tested). The serum and C.S.F. specimens from these two patients were tested for measles antibody by six assay methods. The results were compared with those obtained from serum and C.S.F. specimens of a patient with subacute sclerosing panencephalitis (S.S.P.E.). The gel precipitation line produced by the C.S.F. from the M.S. patients was identical with one of the three lines produced by the C.S.F. from the S.S.P.E. patient. The main antigenic component responsible for measles antibody appearing in the C.S.F. of the S.S.P.E. patient and the M.S. patients was also electrophoretically similar, and the corresponding antibody was associated with IgG. The serum/C.S.F. antibody titre ratios with the various assay methods used suggest that the C.S.F. antibodies are mainly to other than envelope components of measles virus. No complement-fixing antibody against 27 other viruses or Mycoplasma pneumoniae was found in the C.S.F. of the two M.S. patients.

Comparison of enzyme-immunoassay and radioimmunoassay for detection of human rotaviruses and adenoviruses from stool specimens

An enzyme-immunoassay (EIA) using polystyrene beads as the solid phase, guinea pig anti-rotavirus or anti-adenovirus immunoglobulin as primary antibody, rabbit anti-rotavirus or anti-adenovirus immunoglobulin as secondary antibody, and horseradish peroxidase-conjugated swine anti-rabbit immunoglobulin as indicator antibody, has been developed for the detection of human rotavirus and adenovirus antigens from stool specimens. A comparison of the developed EIA and radioimmunoassay (RIA) used previously in our laboratory was made with 250 stool specimens from children with acute gastroenteritis. Two specimens were found negative by both rotavirus and adenovirus EIAs but not by RIAs, but in each of these cases confirmatory EIA tests showed them to be false negatives. The confirmatory EIA tests were also necessary in several cases to prove the specificity of the binding or to eliminate non-specific reactions with specimens giving low positive reactions in EIA. The developed EIA was found to be as specific, sensitive and reliable as RIA in the routine diagnosis of rotavirus and adenovirus gastroenteritis provided that appropriate confirmatory tests were included.

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

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.