Influenzaviruses Are Inactivated by the Manufacturing Process of Plasma-Derived Products.

Abstract 2107

Poster Board II-84

The starting material of plasma-derived products, pooled human plasma, may contain the blood-borne viruses HIV, HCV and HBV as well as HAV and B19V. The presence of these viruses in blood has led to cases of virus transmission by blood transfusions and, in the past when these pathogens were incompletely inactivated or removed, also by plasma-derived products. There is a continuous concern for the safety of the starting material for plasma-derived products regarding emerging viruses potentially present in the donor population. These viruses may not be detected because (i) at the time of donation the donor is in the incubation period and appears healthy and (ii) no routine screening test is available to detect emerging viruses. Therefore, the manufacturing process of plasma-derived products must be able to inactivate or remove these pathogens with a high margin of safety. Currently, influenzaviruses are perceived as viruses of risk, especially the pandemic influenzavirus H1N1 and the avian influenzavirus H5N1.

We studied the inactivation of influenzaviruses by pasteurization (heat treatment at 60°C for 10 hours in aqueous solution), a virus inactivation method used in the manufacturing process of a range of plasma-derived products. The influenzavirus strains H1N1 (A/PR/8/34), H5/N2 (A/chick/Pennsylvania/1/83), H7N1 (FPV/Rostock/34) and H5N1 (A/Cygnus/Germany/06) were used in virus validation studies employing a laboratory scale of the manufacturing process. This scaled-down process was validated to mimic the production process as closely as possible, i.e. appropriate product intermediates were obtained from the production facility and spiked with virus stocks. The heat treatment was performed according to production parameters resulting in identical conditions of protein concentration, pH, temperature, time etc for different coagulation factor concentrates (VWF/FVIII; FVIII; FIX) as well as ATIII. The virus strains were propagated in a chicken cell line (CER-3, established at CSL Behring) and the virus infectivity was quantified on MDCK cells based on a cytopathogenic effect. The data demonstrate these strains of influenzaviruses are highly sensitive to heat treatment: after a heat treatment of 6 hours or less, no infectious virus could be detected. The pasteurization step demonstrated an inactivation factor for each strain of at least ≥ 4.4 log₁₀. We plan to study additional influenzavirus strains, as well as further products, to increase the robustness of the data base showing the effective inactivation of influenzaviruses by this heat treatment method alone.