Influence of host cells on the infectivity and neutralizability echovirus type 4 (Pesascek).

The heterogeneity of echovirus type 4 (strain Pesascek) is documented. This strain had a higher EOP on RD cells than on GMK-AH1 or primary green monkey kidney cells. It was more effectively neutralized in tests on RD cells than on GMK-AH1 cells. The latter phenomenon was analyzed on materials of Pesascek virus after banding in density gradients. A minor fraction was found that resisted neutralization as tested on either RD or GMK-AH1 cells. Another fraction containing the main peak of infectivity was rendered almost harmless to RD cells by neutralizing antibody, while still infecting GMK-AH1 cells. Filtration diminished the non-neutralizable fraction of virus, as did treatment of virus with disrupted membranes. The validity of the theory which holds aggregation of virus responsible for the non-neutralizable fractions, as well as the role played by different host cells for neutralizability, are discussed.

Most echoviruses reach higher titers in RD than in GMK-AH 1 cells, regardless of their passage history.

Stocks prepared in GMK-AH 1 cells of all 31 echovirus prototype strains were titrated simultaneously from identical dilution series in tube cultures of RD and GMK-AH 1 cells. 14 types reached titers 10 to 60 times higher in RD than in GMK-AH 1 cells. 10 other types titered 4 to 6 times higher in RD than in GMK-AH 1 cells. Three prototypes only (Nos. 1, 8 and 9) titered considerably lower in RD than in GMK-AH 1cells. Echovirus types 22 and 23 did not replicate in RD cells. Stocks of the various echoviruses prepared in RD cells mostly gave titer differences between RD and GMK-AH 1 cells similar to those of corresponding stocks from GMK-AH 1 cells.

Neutralization of aggregated strains of enterovirus 71 and echovirus type 4 in RD and Vero or GMK-AH1 cells.

Strains of enterovirus 71 and echovirus type 4 containing aggregates which were poorly neutralized by antibody in cell lines of green monkey kidney origin such as Vero and GMK-AH1, were as easily neutralized as non-aggregated strains when grown in human RD cells, The explanation for this may be a lesser degree of aggregation of viral materials originating from RD cells and/or the use of lower doses of virus for neutralization tests in such cells. The latter was a consequence of a higher sensitivity of RD cells to minimal amounts of virus than that shown by Vero and GMK-AH1 cells. Thus, virus grown in RD, Vero or GMK-AH1 cells reached a titre 10 to 100 times higher in RD cells than in the other cell lines.

Epidemiological events surrounding a paralytic case of poliomyelitis in Sweden.

A case of clinical poliomyelitis occurred in Sweden in January 1977; it was the first indigenous case in Sweden since 1962. This incident was of particular interest as it provided an opportunity to study the spread of virus in a cluster of unvaccinated persons and in individuals more or less fully vaccinated with inactivated vaccine. The patient excreted wild type 2 virus and the same type was isolated from 25 other individuals, all of whom were close contacts of virus excretors. Among the close contacts, 14 of 20 unvaccinated preschool children were found to excrete virus, but excretion was not found in any of the 7 vaccinated children examined.

Purification from euglobulin of the first component (C1) of complement and its subcomponents by heparin-sepharose chromatography.

Most of the C1 material of euglobulin was adsorbed to heparin-Sepharose at an ionic strength of 0.265. After desorbtion at an ionic strength of 0.415 the C1 material was found to be purified six to seven-fold. Highly purified subcomponents C1q, C1r and C1s were recovered at DEAE-Sephadex chromatography from such purified C1 material after EDTA-treatment. Tests on isolated C1q, C1r and C1s disclosed in addition to the well known interaction between heparin and C1q an equally strong or even stronger interaction between heparin and C1s. Even C1r was adsorbed to heparin although by somewhat weaker ionic bonds.