INFLUENCE OF pH AND OF CERTAIN OTHER CONDITIONS ON THE STABILITY OF THE INFECTIVITY AND RED CELL AGGLUTINATING ACTIVITY OF INFLUENZA VIRUS

Abstract

A factor of considerable importance to the stability of the infectivity of influenza virus is pH. Andrewes and Smith found in preliminary experiments that the infectivity of the W.S. strain of influenza virus was fairly stable between pH 7 and 9 but that it was unsafe to keep the virus very long on the acid side of pH 7 (1). Ostrovskaya and coworkers reported that the influenza virus which they studied was most stable at pH 7.0-7.5 (2). Stock and Francis found the PR8 strain to be most stable at pH 7.0 (3).The effect of pH upon the chicken red blood cell agglutinating (CCA) activity of preparations of influenza virus has not, however, been tested. Since the measurement of CCA activity as well as of infectivity can be used as a biological test for the characterization of influenza virus (4), it is of importance to establish conditions of maximum stability for both. Such a study would possess the added interest that the determination of the relative pH stabilities of the different biological activities might yield information bearing upon the question of whether or not both activities arise from one and the same particle. Accordingly, a detailed investigation has been made of the pH stability of strains of influenza virus with respect both to infectivity and to CCA activity.The present studies were carried out with preparations of PR8, Lee, and swine viruses concentrated and purified from the allantoic fluid of infected chick embryos by means of differential centrifugation. Previous investigators (1-3) employed suspensions or filtrates of infected mouse lungs. In order that the importance of temperature to the stability of the virus might be determined, certain of the experiments were carried out at room temperature and others at 4 ° C. Observations also were made on the effect of the composition of the buffers and of the concentration of the virus protein on the stability of the virus.

A Mechanistic Study on the Destabilization of Whole Inactivated Influenza Virus Vaccine in Gastric Environment

“…As shown in Figure S5, a highly diluted vaccine was proven to be more susceptible to osmotic stress-induced HA activity loss (two-way ANOVA, P <0.001), which is consistent with a previous report [56]. Even at iso-osmotic condition, highly diluted vaccine exhibited a significantly lower HA activity than a relatively less diluted one (Student’s t -test, P <0.001).…”

The Effect of pH on Soil Actinophage

“…The rapid transition towards instability over a small pH range (0.5 units) is characteristic of the acid denaturation of protein. Similar results have been obtained with various animal, plant and bacterial viruses (Finkelstein et al, 1940;Miller, 1944;Best & Samuel, 1936;Putnam et al, 1949;Riverin et al, 1970). The survival of actinophage in soils of near-neutral pH was good, although some inactivation occurred over a 200 h period.…”

Influenza A virus isolation, culture and identification

“…Use sterile plastic collection tubes without transport medium for liquid sample collections. If feasible, chill all sample collection tubes and transport buffers to 0–4°C prior to use, as this temperature has been shown to preserve viral RNA, hemagglutinating activity and virus infectivity 65–67 .…”

“…■PAUSE POINT Do not store samples longer than 72 h at 4°C to avoid loss of viability 65–67 . If frozen, samples can be stored at −80°C for a minimum of several months.…”