Significant neutralizing activity of human immunoglobulin preparations against pandemic 2009 H1N1

Preparation of commercial quantities of a hyperimmune human intravenous immunoglobulin preparation against an emerging infectious disease: the example of pandemic H1N1 influenza

“…The antibody titers against the pandemic H1N1 virus as detected in preparations collected or produced before the first occurrence of the virus may seem surprisingly high. However, these titers are in agreement with what has earlier been observed for prevaccination subjects during H1N1 vaccine trials 22‐24 and consequently also for IVIG preparations 25,26 . These antibody titers can be explained by years of infection with or vaccination against previous seasonal H1N1 virus strains, which would have induced a certain level of cross‐reactive, yet not necessarily cross‐protective, antibodies.…”

A case of acute respiratory distress syndrome associated with novel H1N1 treated with intravenous immunoglobulin G

“…11 Another observation by researchers was the association of low total immunoglobulin subclass levels, particularly IgG2, in both pregnant and nonpregnant H1N1 2009 patients who developed respiratory failure. 12 In management of this case, IV IgG was administered on the basis of its potential immune-modulator properties and neutralizing antibodies, which may partly contribute to a favorable outcome of this patient.…”

Antibodies to vaccine antigens in pooled polyclonal human IgG products

“…In contrast, those born after 1950 have very little antibody against the 2009 virus, which certainly contributed to the pandemic it caused. Interestingly, several lots of Japanese IVIG made in 2008 had hemagglutinin‐inhibiting (HI) titers of 1:8 and viral neutralizing titers of 1:64 against this virus, but much higher HI and neutralizing titers against seasonal viruses from 1999 and 2008, suggesting cross reactivity . Going a step further, as shown in Fig.…”