Pertti Arstila

Waterborne Outbreak of Viral Gastroenteritis

A waterborne epidemic took place in a Finnish municipality in April 1994. Some 1500-3000 people, i.e. 25-50% of the population, had symptomatic acute gastroenteritis. Laboratory findings confirmed adenovirus, a Norwalk-like agent, small round viruses (SRV), and group A and C rotaviruses as causative agents, Norwalk virus being the main cause of the outbreak. The epidemic was most probably associated with contaminated drinking water. The groundwater well, situated in the embankment of a river, was contaminated by polluted river water during the spring flood. A back flow from the river to the well had occurred via a forgotten drainage pipe.

Sinusitis in the common cold

Abstract Background: Acute community-acquired sinusitis is considered a bacterial complication of the common cold. Radiologic abnormalities in sinuses occur, however, in most patients with upper respiratory virus infections. Objective: Assessment of the occurrence, clinical profile, laboratory findings, and outcome of radiologically confirmed sinusitis was carried out as part of a common cold study in young adults. Methods: Clinical examinations and radiography of the paranasal sinuses were carried out on days 1, 7, and 21 in 197 patients with the common cold. The symptoms were recorded on diary cards on days 1 to 20. Ten viruses and 5 bacteria were studied as etiologic agents of common cold as reported earlier. Serum C reactive protein concentrations, erythrocyte sedimentation rates, and total white blood cell counts with differentials were determined in 40 randomized subjects on day 7. The effect of 6 days of intranasal fluticasone propionate treatment of the common cold in the prevention of sinusitis was analyzed. Results: On day 7, 39% of patients with the common cold in the placebo group (n = 98) had sinusitis, which we would prefer to call viral sinusitis. The symptoms of patients with sinusitis and those without it were not clinically distinguishable. Viral infection was detected in 81.6% of patients with sinusitis. No significantly increased levels of antibodies to bacteria were detected. Serum C reactive protein concentrations, erythrocyte sedimentation rates, and white blood cell counts were low in patients with sinusitis. All patients made a clinical recovery within 21 days without antibiotic treatment. Fluticasone propionate treatment tended to prevent paranasal sinusitis, especially in rhinovirus-positive subjects. Conclusion: Viral sinusitis frequently occurs in the early days of the common cold, but it is a self-limited illness. The sinuses should not be imaged in patients with the common cold if the signs and symptoms of illness gradually become less severe and no specific signs suggestive of bacterial sinusitis occur. (J Allergy Clin Immunol 1998;102:403-8.)

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.

Detection of human papilloma virus (HPV) DNA in genital biopsy specimens by in situ hybridization with digoxigenin-labeled probes

The presence of human papillomavirus (HPV) nucleotide sequences in paraffin sections of genital biopsies was examined by in situ hybridization using non-isotopic, digoxigenin-labeled probes representing HPV types 11, 16 and 18. Digoxigenin-labeling of the probes was performed using DNA labeling and a commercially provided detection kit. Hybridization was performed under stringent conditions. The hybrids were detected by using anti-digoxigenin alkaline phosphatase conjugate and visualized with enzyme catalyzed color reaction. In situ hybridization with digoxigenin-labeled probes was a useful technique for identification of HPV infection. The results were compared with the results obtained with radiolabeled DNA probes. The sensitivity of the digoxigenin-labeled probes was equal to the sensitivity of the radiolabeled probes. The background with digoxigenin-labeled probes was very low. Using nonradioactive probes the localization of hybrids at the cellular level was better than 35S-labeled probes.

Direct Antigen Detection

A direct detection of viral particles, antigens or nucleic acids in clinical samples is the most straightforward strategy for specific viral diagnosis. Almost always, it is also the most rapid diagnostic method. Detection of virus particles requires electron microscopy, and detection of nucleic acids is done by hybridization methods, whereas antigen detection is done by immunologic methods using specific hyperimmune sera or monoclonal antibodies.

Typing of herpes simplex virus isolates with monoclonal antibodies and by nucleic acid spot hybridization

Fifty-one clinical isolates of herpes simplex virus (HSV) were typed by an enzyme immunoassay (EIA) using mouse monoclonal antibodies, by DNA spot hybridization, and by restriction enzyme analysis using restriction endonuclease Eco RI. Extracts of VERO cells infected with the isolates were used for coating microtitre plates or denatured and spotted onto nitrocellulose filters. Viral antigens passively adsorbed to microtitre plates were detected by an indirect EIA using mouse monoclonal antibodies specific for HSV type 1 (HSV-1) or HSV type 2 (HSV-2). Spotted DNA was hybridized with 32P-labeled probes containing Hind III/Sal I-fragments of either HSV-1 or HSV-2 DNA and bound radioactivity was detected by autoradiography and counted in a liquid scintillation counter. All the three methods gave identical results for the 51 isolates studied. Twenty-six isolates were identified as HSV-1 and 25 as HSV-2. An additional 30 specimens were tested only by EIA and hybridization. Results by both techniques were in complete agreement.

Solid-phase enzyme-immunoassay for the detection of herpes simplex virus antigens in clinical specimens

An indirect solid-phase enzyme-immunoassay (EIA) for the detection of herpes simplex virus (HSV) antigens in clinical specimens was developed. Rabbits and guinea pigs were hyperimmunized with highly purified nucleocapsids of HSV type 1. Microtitre plates were coated with 0.25 microgram of guinea pig anti-herpes simplex type 1 immunoglobulins per well. Clinical specimens, diluted in phosphate buffered saline containing fetal calf serum and detergents, were sonicated and incubated in the test wells overnight at 37 degrees C. Rabbit anti-HSV immunoglobulins were added as a secondary antibody at a concentration of 3.2 micrograms per well, and peroxidase conjugated swine antibodies against rabbit immunoglobulins, diluted 1:1,000, were used as a fourth layer. Clinical specimens which were sent for virus isolation or for isolation of Chlamydia trachomatis were tested by the developed assay and 20 out of 27 isolation positive specimens were found positive by EIA. Five out of 67 specimens negative by isolation gave positive results by EIA. The specificity of the results was confirmed by a control test using wells coated with normal guinea pig immunoglobulins. The test detected antigens from both serotypes of HSV. Cross reactions with varicella-zoster- or with cytomegalovirus were not found, and antigens from uninfected cells did not result in false positive results.

Hemagglutinin of vesicular stomatitis virus

Hemagglutinin of vesicular stomatitis virus was prepared in suspension culture of BHK21/13 S cells maintained in a medium containing 0.4% bovine albumin and no serum. Optimal conditions for titration of VSV hemagglutinin included a low temperature, pH 5.8 and the use of goose erythrocytes. The hemagglutination pattern, once fully developed, remained fairly stable. Hemagglutinin was completely inactivated in one minute at 56°C; at 35°C it was stable for several days at pH 9.0. In density gradient centrifugation the peak HA activity was found in fractions of 1.22 to 1.24 g/ml, in which virions were also demonstrated by electron microscopy. Nonspecific inhibitors, present in high titers in normal rabbit serum, were removed by modified kaolin treatment. Specific HI titers in hyperimmune rabbit serum were low but increased slightly with ether- or fluoro-carbon-treated hemagglutinins and with a concentrated hemagglutinin.

Characterization of the Common Immunodominant Antigenic Determinant in the Lipopolysaceharide of Bacteroides fragilis by a Monoclonal Antibody

The target determinant of a monoclonal antibody (MoAb) to Bacieroides fragilis lipopolysaccharide (LPS) was characterized by inhibition enzyme immunoassay (EIA), inimunoblotting (IB), immunofluorescence technique (IF) and electron immunocytochemical (EIC) technique. The MoAb has been shown to react positively with 96+ of B. fragilis isolates. LPS preparations from 14 different B. fragilis strains were tested by EIA and IB. Two LPS preparations did not react in any of the tests. In both preparations the o‐galactose was either lacking or present in low amount compared with the other LPSs. In addition, inhibition experiments with synthetic disaccharides confirmed that the target determinant is composed of β‐l, 6‐iinked galactose disaccharide. EIC showed that the target of the LPS‐MoAb is located on the surface of the outer membrane. These results show that the galactose chain present in LPS isolated from most B. fragilis strains contains the immunodominant antigenic determinant.

Surveillance of Human Immunodeficiency Virus (HIV) Antibodies in Medicolegal Autopsies in Finland—Monitoring Early Changes in HIV-Seropositivity Among Risk Groups and Average Population

In order to cooperate with voluntary screening programs aimed at the surveillance of the HIV epidemic in Finland, we have studied medicolegal autopsies for HIV antibodies since 1986 using an enzyme immunoassay on postmortem sera. The investigation covered 47.4% and 39.2%, respectively, of all deaths under the age of 65 years in the metropolitan areas of Helsinki and Turku--two cities on the densely populated southern coast of Finland from which most HIV infections have thus far been detected. Nine HIV-positive cases (0.12%) were detected among the 7305 medicolegal autopsies tested in 1986 to 1990. This figure is higher than the prevalence of 0.01 to 0.03% in voluntary screening programs for the general population would suggest. Seven of our cases had previously tested positive, and two were previously unknown cases, indicating that people at high risk are clustered in the medicolegal autopsy series. Of the six cases in an early stage of infection, three committed suicide suggesting the importance of HIV-screening in suicide cases in tracing symptomless HIV carriers. Five of the cases were detected in 1990, a year when the number of new HIV infections had more than doubled compared to the previous two years. This suggests that testing of medicolegal autopsies as surrogate tests for the population gives useful information even in low-prevalence areas like Finland. Such testing has none of the ethical problems of many other back-up surveys, and may be particularly sensitive to early changes in epidemiology.