Frank Lanni

Determination of Small Quantities of Nitrogen in Serological Precipitates and Other Biological Materials.

Summary A simple and accurate colorimetric method is described for the routine determination of quantities of nitrogen in the range from 5 to 80 y. The method, which is a modification of the direct-nesslerization procedure of Koch and McMeekin, has been developed especially for the analysis of serological precipitates, but is adapted readily to the analysis of protein solutions.

Inhibition by Egg-White of Hemagglutination by Swine Influenza Virus.

Summary Egg-white (EW) has been found approximately 200 times as effective as normal rabbit serum in inhibiting hemagglutination by heated swine influenza virus, giving titers of about 170,000. An aged formolized vaccine was also highly susceptible to inhibition by EW, but unheated virus and a fresh vaccine required about 750 to 1,000 times as much EW for similar inhibition. In addition, EWT gave an interfacial precipitation reaction with concentrated virus suspensions, and both the precipitating and inhibiting capacities were destroyed by treatment with dilute periodate.

Dialyzable Factor in Allantoic Fluid Affecting Virus Hemagglutination-Inhibition Reactions.

Summary The difference between purified and unpurified swine influenza virus with respect to development of inhibitor sensitivity on heating is ascribed to a factor, identified as calcium, occurring in, normal and virus-infected allantoic fluids. The factor, which is lost, or considerably diminished, during purification, may be removed also by dialysis or neutralized by citrate and oxalate. Calcium, in low concentration, depresses the development of inhibitor sensitivity by swine influenza virus on heating; magnesium is ineffective. In contrast with the swine virus, influenza virus A (PR8 strain) is relatively insensitive to calcium. This difference between two viruses suggests a possible explanation for the generally observed variation among influenza viruses with respect to development of inhibitor sensitivity on heating.

Electrical Precipitation of Egg-White Inhibitor of Influenza Virus Hemagglutination.∗

Summary Precipitation occurs in solutions of egg-white or purified egg-white inhibitor of virus hemagglutination submitted to an electric field. The precipitate includes a great part of the inhibitor of the preparations in a state substantially purer than that of the starting material. This result suggests application of the phenomenon to the final purification of the inhibitor.

Reações entre caolim, virus de influenza suína e inibidor de clara de ôvo da hemoaglutinação de vírus

Kaolin adsorbs inhibitory activity more rapidly than total nitrogen from crude egg-white and less rapidly than total nitrogen from semipurified inhibitor preparations. The adsorption of inhibitoris reversible. Treatment of semipurified preparations with active swine influenza virus causes a slight increase in the adsorption of activity and total nitrogen. Active virus combines with inhibitor-coated kaolin in the cold and can be recovered in great part at room temperature. A smaller amount of virus is bound by untreated kaolin. Heating the virus for 30 minutes at 53°C increases its adsortion by kaolin.

Inhibitory Effect of Cow's Milk on Influenza Virus Hemagglutination.

Summary Milk is capable of inhibiting hemagglutination by influenza viruses, the inhibitory effect being greater against heated than against unheated viruses. The inhibitor, which is non-dialyzable and moderately heat stable, occurs in the whey and can be salted out by half-saturation with ammonium sulfate. Evidence is presented that the inhibitor is a characteristic component of milk rather than a specific antibody.

The Mechanism of Egg-White Inhibition of Hemagglùtination by Swine Influenza Virus.

Summary Evidence has been presented that the mechanism of egg-white inhibition of hemagglutination of chicken red blood cells by swine influenza virus involves combination between an egg-white component and the virus, this combination obstructing the reaction of virus with red blood cells. Moreover, it has been found that the inhibitor is rapidly inactivated by highly infectious virus, with regeneration of the virus, but not by an aged formolized vaccine consisting of inactivated virus; and that the inactivation of inhibitor by virus is suppressed by convalescent (anti-influenza) swine serum. The results have been interpreted in terms of an enzymatic hypothesis of virus function in the phenomenon.

Purification of the Egg-White Inhibitor of Influenza Virus Hemagglutination by Filtration.

Summary A simple method is described for the purification of the egg-white inhibitor of influenza virus hemagglutination by filtration of diluted egg-white through rapid-flow filter papers and extraction of the unfilterable residue. The inhibitor has been purified about 80-fold in this way. The method has proved useful also for the further purification of acid-purified inhibitor. The advantages and disadvantages of the new method are discussed in relation to those of other methods.

Influence of Detergents on Egg-White Inhibition of Hemagglutination by Formolized Swine Influenza Virus.*

Summary Investigation of the origin of irregular titration results has led to the Observation that soaps and synthetic ionic detergents exert a great effect on the character of inhibition titrations involving purified, formolized swine influenza virus (vaccine) and the egg-white (EW) inhibitor of vaccine hemagglutination. The amount of detergent needed for such an effect is of the order of the amount which is sufficient to cover the internal glass surface of a titration tube with a single, close-packed uniniolecular layer. While the detergent effect shows a dependence on detergent concentration, there exists a broad range of detergent concentrations over which the effect on the inhibition is essentially constant. For reasons indicated, the effect of detergent has been provisionally interpreted as an effect on the interaction of EW inhibitor and vaccine. The mechanism of the detergent effect is being investigated and will be the subject of a subsequent report.

Interaction of swine influenza virus and egg-white inhibitor of virus hemagglutination.

Summary During the interaction of swine influenza virus and egg-white inhibitor of hemagglutination, there appears a weak inhibitor, which has titrating properties different from those of untreated inhibitor. This result renders impossible a simple kinetic treatment of the data. The significance of the weak inhibitor for the mechanism of virus-inhibitor interaction is discussed.