Suspensions Of Influenza Virus Research Articles

Protection from H1N1 Influenza Virus Infections in Mice by Supplementation with Selenium: A Comparison with Selenium-Deficient Mice

The present paper describes protective effects of supplemental selenium in mice infected with influenza virus. The effects of supplemental selenium on serum selenium levels, mortality, lung virus titers, and cytokine titers were investigated in mice inoculated intranasally with suspensions of influenza virus. Whereas the mortality of the virus-infected Se-deficient mice was 75%, along with a marked reduction in body weight, lower levels of TNF-α and IFN-γ and lower serum selenium concentrations, the mortality of mice maintained on feed containing 0.5mg Se/kg in the form of sodium selenite was 25%.There were no significantly differences, however, in viral titer between the Se-adequate and the selenium-supplemented groups. The data indicate that selenium supplementation may provide a feasible approach to improving the immune response to viral infections, such as lethal influenza infection.

Stabilities of suspensions of influenza virus dried by sublimation of ice in vacuo to different contents of residual moisture and sealed under different gases.

Suspensions of influenza virus were dried by sublimation of ice in vacuo to contents of residual moisture of 2.8, 1.6, or 0.6%. After drying, the preparations were sealed under helium, argon, nitrogen, or a mixture of oxygen and nitrogen (30% O(2), 70% N(2)). Stabilities of the several preparations were determined by an accelerated storage test. Based on the times predicted for the dried preparations stored at preselected temperatures to lose 1 log of infectivity titer, the order of stabilities in relation to residual moisture, gas was as follows: 1.6%, He > 0.6%, He > 2.8%, He > 1.6%, Ar > 2.8%, N(2) > 2.8%, Ar > 1.6%, N(2) > 2.8%, O(2) > 0.6%, Ar > 0.6%, N(2) > 1.6%, O(2) > 0.6%, O(2). The stability of the preparation sealed under helium and dried to the content of residual moisture found best for this gas (1.6%) resulted in an increased stability of the order of years as compared to the other preparations tested.

Stabilities of Suspensions of Influenza Virus Dried by Sublimation of Ice In Vacuo to Different Contents of Residual Moisture and Sealed Under Different Gases

Suspensions of influenza virus were dried by sublimation of ice in vacuo to contents of residual moisture of 2.8, 1.6, or 0.6%. After drying, the preparations were sealed under helium, argon, nitrogen, or a mixture of oxygen and nitrogen (30% O(2), 70% N(2)). Stabilities of the several preparations were determined by an accelerated storage test. Based on the times predicted for the dried preparations stored at preselected temperatures to lose 1 log of infectivity titer, the order of stabilities in relation to residual moisture, gas was as follows: 1.6%, He > 0.6%, He > 2.8%, He > 1.6%, Ar > 2.8%, N(2) > 2.8%, Ar > 1.6%, N(2) > 2.8%, O(2) > 0.6%, Ar > 0.6%, N(2) > 1.6%, O(2) > 0.6%, O(2). The stability of the preparation sealed under helium and dried to the content of residual moisture found best for this gas (1.6%) resulted in an increased stability of the order of years as compared to the other preparations tested.

Stabilities of dried suspensions of influenza virus sealed in a vacuum or under different gases.

Suspensions of purified influenza virus, dried to a 1.4% content of residual moisture by sublimation of ice in vacuo, were sealed in a vacuum or under different gases of high purity. The stabilities of the several preparations were determined by an accelerated storage test. Based on the times predicted for the dried preparations stored at different temperatures to lose 1 log of infectivity titer, the order of stabilities in relation to sealing in vacuum or under different gases was as follows: helium > hydrogen > vacuum > argon > nitrogen > oxygen > carbon dioxide.

Stabilities of Dried Suspensions of Influenza Virus Sealed in a Vacuum or Under Different Gases

Suspensions of purified influenza virus, dried to a 1.4% content of residual moisture by sublimation of ice in vacuo, were sealed in a vacuum or under different gases of high purity. The stabilities of the several preparations were determined by an accelerated storage test. Based on the times predicted for the dried preparations stored at different temperatures to lose 1 log of infectivity titer, the order of stabilities in relation to sealing in vacuum or under different gases was as follows: helium > hydrogen > vacuum > argon > nitrogen > oxygen > carbon dioxide.

Stability of suspensions of influenza virus dried to different contents of residual moisture by sublimation in vacuo.

After freezing, suspensions of influenza virus were dried by sublimation of water in vacuo to contents of residual moisture of 3.2, 2.1, 1.7, 1, or 0.4%. The stability of the several suspensions was determined by an accelerated storage test. Based on the times predicted for the dried preparations stored at different temperatures to lose 1 log of infectivity titer, the order of stability in relation to residual moistures was as follows: 1.7% > 2.1% > 1% > 3.2% > 0.4%.

Stability of Suspensions of Influenza Virus Dried to Different Contents of Residual Moisture by Sublimation In Vacuo

After freezing, suspensions of influenza virus were dried by sublimation of water in vacuo to contents of residual moisture of 3.2, 2.1, 1.7, 1, or 0.4%. The stability of the several suspensions was determined by an accelerated storage test. Based on the times predicted for the dried preparations stored at different temperatures to lose 1 log of infectivity titer, the order of stability in relation to residual moistures was as follows: 1.7% > 2.1% > 1% > 3.2% > 0.4%.

Structures associated with influenza virus suspensions treated with phospholipase C

Structures associated with influenza virus suspensions treated with phospholipase C

Evidence for the Absence of Anaphylactogenic Host Protein in Highly Purified PR8 Influenza Virus

Summary The anaphylactogenic properties of crude sedimented and highly purified PR8 influenza virus suspensions were investigated by the Schultz-Dale reaction with excised uterine muscle from sensitized guinea pigs. It was shown that the specificity of the in vitro anaphylactic reaction with crude sedimented virus is related to the host protein present in the virus suspensions and not to the specific viral antigen. When PR8 influenza virus was concentrated from infected chorioallantoic fluid by one cycle of ultracentrifugation or by one cycle of adsorption and elution from chicken erythrocytes, the presence of host protein could readily be detected by Schultz-Dale reactions with uterine muscle taken from guinea pigs previously sensitized with normal chorioallantoic membrane antigen, but, when the first cycle eluates were further purified by a second cycle of adsorption and elution from guinea pig erythrocytes, host material could be detected in only trace amounts in two separate virus suspensions. Finally, sedimentation of the second cycle eluates in the ultracentrifuge yielded two preparations which contained no detectable amount of host protein. The data presented in this investigation appear to be irreconcilable with the hypothesis that normal anaphylactogenic host protein is incorporated on the surface of the PR8 influenza virus elementary body during replication in the chorioallantois of the embryonated egg.

The use of beta-propiolactone for the preparation of virus vaccines. II. Antigenicity.

An investigation has been made of the antigenicity of influenza virus suspensions rendered noninfective with beta-propiolactone (BPL). By treatment with BPL under various conditions, influenza vaccines could be prepared which were antigenic as indicated by production of specific antibody response in mice and guinea pigs. These vaccines were also immunizing as evidenced by their capacity to protect mice against challenge with live virus.

Surviving tissue suspensions for influenza virus titration.

A new method of titrating the infectivity of egg-adapted influenza virus suspensions is described.For this purpose a plastic tray has been made, drilled with one hundred conical cups. In each cup a small piece of chorio-allantoic membrane from a chick embryo is suspended in a buffered salt solution. To these surviving tissue suspensions virus dilutions are added, and the tray is put in an incubator and rocked mechanically for 60 hr.In those cups in which the inoculum has been sufficiently large, the membrane becomes infected by the virus which multiplies within the cells and, bursting out, builds up by infection of other cells a high concentration of virus in the suspending fluid. The virus multiplication is detected by removing the pieces of tissue and adding to the cups a drop of washed chicken erythrocytes. The presence of virus in the cup is shown by the pattern of the sedimented erythrocytes, and virus multiplication is inferred because the original seed virus is too dilute to be detectable by haemagglutination.The method has been compared with in ovo titration. As a means of detecting egg-adapted infective virus, the tissue suspension is between 20 and 80 times less sensitive; as a titration system, however, approximately one cup is equivalent to one egg, so that by using sufficient replicates accurate assays of infective virus can be made.The technique is readily adaptable to the titration of serum-neutralizing antibodies.In addition to haemagglutination, the infectivity end-point of the titration can also be estimated by a specific complement fixation test, and it is suggested that, with modifications, the new technique may be applicable to the titration of a large number of other viruses.

ADJUVANTS IN IMMUNIZATION WITH INFLUENZA VIRUS VACCINES

Subcutaneous inoculation, of PR8 allantoic fluid, or watery suspensions of the virus obtained from allantoic fluid by high-speed centrifugation or by elution after adsorption on red cells induced serum antibodies in experimental animals, which reached the highest levels within 2 weeks after inoculation and were gradually lost thereafter. The addition of killed acid-fast bacteria (Myco. tuberculosis or butyricum), paraffin oil, and a proprietary adsorption base (Falba) to form a stable water-in-oil emulsion of influenza virus suspensions greatly enhanced and maintained immunity and antibody response to the virus. These adjuvants provided a much more effective method of increasing antibody production to the virus than the use of concentrated preparations of virus alone. Paraffin oil and Falba without the acid-fast bacilli were less effective as adjuvants, although the antibody levels induced were higher than those produced by watery suspensions of the virus and were maintained at a constant level for at least 6 months. Myco. butyricum appeared to be more effective in producing antibodies against the virus than the tubercle bacilli in the emulsions of paraffin oil and Falba. Immunization with these adjuvants and suspensions of influenza virus obtained from allantoic fluid induced antibodies not only against the virus but against antigenic material contained in normal allantoic fluid, although the latter titers were considerably lower. A suspension of influenza virus (sedimented by high-speed centrifugation) and Myco. butyricum in sesame oil induced about four times as much antibody as when the virus was suspended in saline, in sesame oil alone, or in combination with typhoid bacilli.

Studies on air-borne virus infections: III. The killing of aerial suspensions of influenza virus by hypochlorous acid

Experiments are described for determining the effect of hypochlorite mists and hypochlorous acid gas on aerosols of influenza A virus.The virus aerosol is shown to be at least as easily killed by hypochlorite mists as Streptococcus salivarius. It is also killed by liberating hypochlorous acid gas itself into the atmosphere. A concentration of 1 vol. of gas in 2 million vol. of air is probably effective in destroying 99% or more of virus particles when the proportion of these in the air is small.Preliminary experiments on mice and cats are recorded which failed to reveal any toxic effects produced by inhaling the gas in relatively high concentrations or for prolonged periods. Acute irritation of mucous membranes only was found. This did not appear to lead to any increased susceptibility of mice to subsequent infection with influenza.We wish to acknowledge our indebtedness to the late Sir Patrick Laidlaw and to Dr R. J. V. Pulvertaft in co-operation with whom the earlier experiments were made. We also wish to thank Dr W. J. Elford, Dr F. C. MacIntosh, Dr R. K. Callow and Dr T. S. Work for their assistance and advice in parts of the investigation.

A Method for the Removal of Bacterial Contaminants from Suspensions of Influenza Virus

A Method for the Removal of Bacterial Contaminants from Suspensions of Influenza Virus

ADSORPTION OF INFLUENZA HEMAGGLUTININS AND VIRUS BY RED BLOOD CELLS

A number of experiments were performed on the adsorption of influenza hemagglutinins on chicken red blood cells, from which the following conclusions were drawn:- 1. When chicken red blood cells and preparations of influenza viruses were mixed together, the influenza hemagglutinins present were rapidly adsorbed onto the cells. After varying lengths of time, dependent on the conditions of the experiment, the adsorbed hemagglutinins began to elute from the cells. With the Lee strain at 23 degrees C. and the PR8 strain at 37 degrees C. almost all of the adsorbed agglutinin was released in 4 to 6 hours. 2. When the number of red cells used for adsorption was increased, the speed and degree of adsorption of the hemagglutinins increased. The time of maximum adsorption of hemagglutinins was the same, regardiess of red cell concentration, and with the larger amounts of red cells the speed and degree of elution was decreased. 3. When adsorption of PR8 virus agglutinins was carried out at 4 degrees C. the adsorption was rapid and nearly complete. When the reaction was carried out at higher temperatures (27 degrees and 37 degrees C.), the adsorption was equally rapid but was progressively less complete with rise in temperature. At 4 degrees C. the maximum adsorption was not reached for 5 hours; at 27 degrees C. it was reached in 25 minutes; and at 37 degrees C. the greatest degree of adsorption was attained between 3 and 5 minutes. The amount of elution observed at 4 degrees C. at 18 hours was negligible, but the degree of elution increased with temperature so that at 37 degrees C. almost all of the adsorbed agglutinin was released in 6 hours' time. 4. Red cells which had adsorbed and then fully eluted the agglutinin were not capable of adsorbing a detectable amount of fresh agglutinin. In addition, such cells would no longer agglutinate even though exposed to fresh virus suspensions. 5. The hemagglutinin of influenza B virus was capable of being adsorbed on and eluted from several successive lots of chicken red cells without appreciable loss of agglutinating activity. 6. The hemagglutinins of the PR8 and Lee strains were rapidly inactivated at 60 degrees C. The presence of active virus was not necessary for the occurrence of the adsorption-elution reaction on chicken red cells. 7. The activity of the portion of the red cells responsible for the adsorption of the hemagglutinins persisted, though in reduced amount, even after heating for 5 minutes at 100 degrees C. Hemagglutinins were adsorbed and eluted from red cell stroma. 8. The infective agent in influenza virus suspensions was adsorbed by chicken red cells simultaneously with the adsorption of hemagglutinins. 95 per cent of the infective agent was removed from suspension by the red cells after contact for 15 minutes. From then on the infective agent was gradually released from the red cells. After 4 hours the 50 per cent mortality titer of the supernatant fluid was as high as at the beginning of the experiment.