Influenza virus titers

Yang, Y., Lebrec, H., and Burleson, G., Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on pulmonary influenza virus titer and natural killer (NK) activity in rats, Fundam. Appl. Toxicol., 23, 125, 1994. 

Influenza vims strain A/HKx31 was propagated in embryonated chicken eggs. The influenza virus titer ranged from 1 x lo to 1 x lo EID50 as determined by hemagglutination assay with chicken red blood cells. Influenza... 

Greiff [3.24] studied the stability of purified influenza virus of the strain PR 8 in physiological NaCl solution with calcium lactobionate and human serum albumin (each 1 % in the solution). The freezing rate was approx. 1 °C/min down to -30 °C. During the freeze drying, the product temperature was raised in 12 to 16 h from -30 °C to 0 °C and the product was dried at this temperature. After 24 h, the first 145 vials were removed, and additional vials after intervals of 24 h each. The residual moisture content was 3.0,2.0,1.5, 1.0 and 0.5 %. The stability of the freeze dried virus (expressed in days during which the titer of the infectivity decreased by a factor of 10 was most unfavorable at 0.4 % and 3.2 % RM, (4 and 7 days respectively at +10 °C) and best at 1.7 % RM 145 days or more than 1000 days at -10 °C. 

As a result of our experiments, it was shown that the growth properties of the serum do not change after photodynamic treatment. Nevertheless, the infectious titer of influenza virus both in blood serum and allantoic fluid decreased from 6 to 0 log10 EID50 after the treatment. This fact suggests a selectivity of photodynamic treatment regarding the virions. In our opinion, this can be explained by the following. 

Thujae occidentalis herb, Baptisiae tinctoriae root, E. purpurea root, and E. pallida root, were given to mice. After 6 days the mice were inoculated with Influenza virus Type A. They found a statistically significant increase in survival rate, survival time, reduced lung consolidation, and virus titer (14). 

M1P-1q Reduced pulmonary mononuclear infiltrate to challenge with influenza virus resulting in higher titers of influenza virus Less severe autoimmune myocarditis after coxsackie viral infection Knockout has increased MODS mortality and CTL activity Reduced NK-mediated inflammation... 

GZ was investigated in mice infected with influenza virus A2. It significantly increases the survival time of mice exposed with a lethal amount of virus and significantly decreases the virus titer in the lung tissues. It was suggested that GZ may protect the infected mice through the stimulation of IFN-y production by T-cells [158]. GZ was also found to have therapeutic effects on liver disfunction associated with HCMV infections [159] and on retinitis in haemophilic patients with HIV [160]. 

Figure 7. Virus titer (A) and indoleamine 23-dioxygenase activity in mouse Irmg (O) and serum antibody content (9) at intervals after infection with PR8 influenza virus.

The use of experimental animals in testing the activity of chemical germicides in general against viruses is considered neither necessary nor desirable [21]. Established and well-characterized cell lines are the recommended host system. In some cases, such as when working with adenoviruses [22], it is advisable to carry two cell lines one for the preparation of virus pools and the other to assay for its infectivity. The use of embryonated eggs may be needed in rare cases, such as for the production of high-titered pools for influenza viruses. 

In uncomplicated influenza A illness of adults, early amantadine or rimantadine treatment (200 mg/day for 5 days) reduces duration offerer and systemic complaints by 1—2 days, speeds functional recovery, and may decrease the duration of virus shedding. In children, rimantadine treatment may be associated with less illness and lower viral titers during the first 2 days of treatment, but treated children have more prolonged virus shedding. The optimal dose and duration of therapy in children are not established. 

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