Bertil Melén

Inactivation of poliomyelitis virus by formaldehyde

The course of inactivation of poliomyelitis virus by formaldehyde at 25° C was studied on tissue culture material treated by filtration through sintered glass filters. The inactivation curves deviated significantly from that of a chemical reaction of the first order.

Ability of cervical mucus to act as a barrier against bacteria

Abstract Is cervical mucus bactericidal? If not, can bacteria migrate through the mucus? To answer these questions a new method was designed: Cervical mucus was aspirated into a gamma ray-sterilized nylon tubing. It formed a column in the tubing with a length varying from 10 to 60 mm. One end of the mucus-filled tubing was inoculated with Proteus mirabilis. After incubation for 23 hours cultures were taken at various distances from the inoculated end. From 51 women 142 samples of mucus were examined with this method. A bactericidal effect was encountered during all phases of the menstrual cycle. It was least pronounced at the time of ovulation when in most instances bacteria not only remained alive but could also migrate 10 to 40 mm. through the mucus.

Inactivation of poliomyelitis virus by formaldehyde; incubation time in tissue culture of formalin treated virus.

The time elapsing from inoculation until cytopathogenic changes were demonstrable was studied in cultures inoculated with untreated virus and formalin treated virus. End point titrations in roller tube cultures as well as plaque counting in milk dilution bottle cultures were employed. It was found that the incubation period was significantly prolonged with formalin treated as compared to untreated virus. Practical and theoretical aspects on this phenomenon are discussed.

Studies of the Inactivation of Poliomyelitis Virus by Formaldehyde. A Comparison of the inactivation of Suspensions of Poliomyelitis Virus grown in Two Different Tissues by Determinations of the Virus Activity in Two Types of Tissue Cultures.

Batches of virus suspensions produced on human embryonic tissue and on monkey kidney tissue were inactivated by formaldehyde. The decrease in virus activity was followed by titrations in plasma clot cultures of human embryonic lung and in cultures of trypsinized monkey kidney. No difference could be demonstrated in the rate of inactivation between clarified batches derived from human embryonic tissue and batches produced on monkey kidney tissue and filtered through bacteria retaining filters. The course of inactivation deviated from that of a linear relationship between log. virus activity and time.

Experiences with the guinea pig test for immunogenic capacity of poliomyelitis virus and virus preparations

The guinea pig test for antigenicity of poliomyelitis virus and virus preparations is described, and the accuracy of the method is estimated. Seven preparations of poliomyelitis vaccine were submitted to the test, which revealed that they differed widely in antigenic capacity.

Potency of inactivated poliovirus vaccines. The guinea pig test as a routine method

Some experiences of routine use of the guinea pig test for potency of poliovirus vaccines are reported. The accuracy of the test was estimated. The results of tests on fourty-five vaccines from several producers revealed considerable differences in antigenic potency.

Potency of inactivated poliovirus vaccines, an in vitro method for assay of antibody combining capacity

Anin vitro method for determination of antigenic potency of inactivated poliovirus vaccines has been developed. Serial dilutions of vaccine and a fixed amount of live virus are allowed to combine firmly with antibody. By titrations for residual virus activity the dilution of vaccine is determined where neutralization is reduced to a certain limit. The reproducibility of the test results was good. A statistically significant correlation was demonstrated between results of thein vitro test and results obtained with the guinea pig test.

Potency of inactivated poliovirus vaccines. Correlation between antigenic extinction limit titers in guinea pigs and results obtained in man

Antibody responses to four different inactivated poliovirus vaccines were studied in 617 school children without preimmunization antibodies to any type. The results obtained showed a mathematically definable correlation to the antigenic extinction limit titers in guinea pigs of the same vaccines. The pattern of response to the type 2 antigen differed distinctly from those of types 1 and 3.

Antibodies to Poliomyelitis in School Children in Stockholm.

862 six to ten year old children from Stockholm and 602 six to nine year old children from Solna, a suburb of Stockholm, were examined for the presence of neutralizing antibodies against the three types of poliomyelitis virus. About one tenth of the children had antibodies to all three types, while about one third had no demonstrable antibodies at all. The distribution of various antibody patterns differed from estimates of a random distribution in the following respects: The simultaneous presence of antibodies to all three types as well as the absence of any poliomyelitis antibodies at all was found more frequently than expected. In addition, type 1 and type 2 antibodies occurred together more frequently than expected in the Stockholm material. The incidence of poliomyelitis with paralysis following primary infection during the first seven to nine years of life was estimated. It was found to be 5 per 1,000 infections.

Results of an Experimental Vaccination against Poliomyelitis.

Six hundred and thirtyseven children, aged six to ten, were experimentally vaccinated with two injections of formalin treated poliomyelitis virus preparations. They were tested for neutralizing antibodies before and after immunization. The antibody response was strongly dependent upon the pre-inoculation antibody pattern of the children. Those with antibodies to one or two types developed antibody to the remaining type or types to a significantly larger extent than did triple-negative children. No indications were found, that the intradermal administration of vaccine was superior to the subcutaneous route. The injections were spaced three or six weeks apart. The longer interval seemed to give slightly better results. The antibody response to the individual poliomyelitis virus types after administration of trivalent vaccine did not differ from that obtained with monotypic vaccines.