Serological diagnosis of parainfluenza virus infections: verification of the sensitivity and specificity of the haemagglutination-inhibition (HI), complement-fixation (CF), immunofluorescence (IFA) tests and enzyme immunoassay (ELISA).

Using four serological tests paired sera were examined of 117 patients with acute respiratory diseases, in whom parainfluenza viruses (PIV) infection was demonstrated by virus isolation, and of 41 patients with typical clinical mumps symptoms. Comparative analysis showed the high sensitivity of IFA and ELISA. A significant rise of antibodies in convalescent sera with homologous antigen of PIV was found in nearly 100 percent of cases. Only the sera of youngest children with high titres of persisting maternal antibodies remained without seroconversion. Cross heterologous antibody responses could be found by means of ELISA in 45% and by IFA in 10%, of patients who in the past experienced infection with one or more PIV or mumps virus--apart from homologous antibody reaction. HI and CF test proved to be less sensitive for detection of postinfections antibodies, especially in primoinfections with PIV types 1 and 2.

[Surveillance of acute respiratory diseases in the 1988/1989 season in Czechoslovakia]. / Surveillance akutních respiracních onemocnení v sezóne 1988/1989 v CSSR.

The authors submit an analysis of results of surveillance of acute respiratory diseases during the 1988/1989 season in the CSSR. The influenza epidemic took place between the 4th and 11th calendar week with a peak in the 7th week. During the epidemic 19.7% of the population in the CSR contracted the disease. The influenza epidemic was preceded by a high incidence of infections caused by a respiratory syncytia virus. As to the aetiology, influenza viruses subtypes A/H1N1/, A/H3N2/ and type B participated practically equally in the epidemic. The authors discuss the observed changes in the influenza epidemiology in recent years in Czechoslovakia and neighbouring countries.

The source of avian paramyxoviruses isolated during an outbreak of influenza among children.

In 1986 five avian paramyxovirus (PMV) strains were isolated in embryonated chicken eggs from sick children with influenza. The strains were identified as PMV-2 serotype due to the close antigenic relationships between their HN-proteins and of the reference PMV-2 strains isolated from different birds all over the world. No seroconversion to the isolates was found in the sick children, however, HI-antibodies were detected in hen's sera, eggs of which were used for the new strains isolation. The possible origin of isolated PMV-2 viruses is discussed.

[Conservativism of the matrix protein of paramyxoviruses]. / Konservatizm matriksnogo belka paramiksovirusov.

Cross reactions among paramyxoviruses were determined by the immunoblot method. Human parainfluenza viruses, types 1-3, avian parainfluenza virus type 4, mumps, Sendai, and measles viruses were used. Antisera to human parainfluenza viruses were shown to cross-interact with proteins NP and M of other types, and all antisera to the members of Paramyxovirus genus cross-reacted with M proteins of other paramyxoviruses. No cross reactions with measles virus proteins were observed. It is concluded that M protein is the most conservative protein of paramyxoviruses.

Detection of postvaccination mumps virus antibody by neutralization test, enzyme-linked immunosorbent assay and sensitive hemagglutination inhibition test.

A group of 251 children aged 2-3 years given live attenuated mumps virus vaccine PAVIVAC of Czechoslovak production were tested for antiparotitis antibody levels in pre- and postvaccination sera by neutralization test (NT), enzyme-linked immunosorbent assay (ELISA) and sensitive hemagglutination inhibition test, enhanced by heterologous antibody to human immunoglobulin G (E-HIT). The prevaccination findings were as follows: positive ELISA IgG titres, neutralization antibodies and hemagglutination inhibition antibodies were present in, respectively, 35%, 25.9% and 27.9% of the sera. Postvaccination seroconversions were evaluated in 159 susceptible vaccinees whose prevaccination sera had been negative by all three tests. The lowest seroconversion was detected by NT (74.2%), seroconversions by ELISA and E-HIT were appreciably higher (82.4% and 86.8%, respectively). The seven children showing a seroconversion by E-HIT but not by ELISA had a 4 fold increase of anti-mumps ELISA IgG antibodies as well, but the rise of antibody titres was at a level falling in the range below the positivity criterion for ELISA. The statistically evaluated detection rate for antibodies was significantly higher (significance test "t") by ELISA as compared with neutralization test. However, antibody levels (geometric mean titres) were 8-10 times lower in postvaccination sera than in convalescent sera of 30 children with mumps in all three tests.

Incidence of paramyxoviruses in free-living birds in 1978-1982.

Together 41 paramyxovirus (PMV) strains (25 PMV-1, 10 PMV-4, and 6 PMV-6 serotypes) were isolated from cloacal swabs of 910 free-living birds trapped in West Slovakia from 1978 to 1982. The PMV strains were found in 9, mostly aquatic bird species. Strains belonging to the PMV-1 serotype were isolated yearly, indicating its wide distribution and circulation in nature. The strains of PMV-4 and PMV-6 serotypes found only in 1978-1980, represented the first isolations in Europe. Antigenic analysis by haemagglutination-inhibition (HI), neuraminidase-inhibition (NI), complement-fixation (CF), and gel double diffusion (DD) tests proved the relatedness of the surface antigens of newly isolated PMV strains with those of PMV-4/ Duck Hong Kong D3/75 and PMV-6/Duck/Hong Kong 311/80 strains. One-way reaction between PMV-4 serotype and mumps virus was demonstrated using hyperimmune rat sera. Electron microscopic observation of isolated virus strains revealed structures typical of PMV.