Abstract
Four kinds of avian-derived H5N1 influenza virus, A/Vietnam/1194/2004 (Clade 1), A/Indonesia/5/2005 (Clade 2.1), A/Qinghai/1A/2005 (Clade 2.2), and A/Anhui/1/2005 (Clade 2.3), have been stocked in Japan for use as pre-pandemic vaccines. When a pandemic occurs, these viruses would be used as vaccines in the hope of inducing immunity against the pandemic virus. We analyzed the specificity of antibodies (Abs) produced by B lymphocytes present in the blood after immunization with these vaccines. Eighteen volunteers took part in this project. After libraries of Ab-encoding sequences were constructed using blood from subjects vaccinated with these viruses, a large number of clones that encoded Abs that bound to the virus particles used as vaccines were isolated. These clones were classified into two groups according to the hemagglutination inhibition (HI) activity of the encoded Abs. While two-thirds of the clones were HI positive, the encoded Abs exhibited only restricted strain specificity. On the other hand, half of the HI-negative clones encoded Abs that bound not only to the H5N1 virus but also to the H1N1 virus; with a few exceptions, these Abs appeared to be encoded by memory B cells present before vaccination. The HI-negative clones included those encoding broadly cross-reactive Abs, some of which were encoded by non-VH1-69 germline genes. However, although this work shows that various kinds of anti-H5N1 Abs are encoded by volunteers vaccinated with pre-pandemic vaccines, broad cross-reactivity was seen only in a minority of clones, raising concern regarding the utility of these H5N1 vaccine viruses for the prevention of H5N1 pandemics.
Highlights
Since the direct bird-to-human transmission of highly pathogenic avian influenza (HPAI) H5N1 virus occurred in Hong Kong in 1997, such viruses have spread to countries in Asia, the Middle East, Africa, and Europe [1]
The introduction of mutations in hemagglutinin (HA)-encoding sequences of highly malignant avian H5N1 influenza viruses has the potential to endow HPAI with the ability to spread by human-to-human transmission, which could result in a pandemic [2]
We analyzed the strain specificity of Abs that were present in the blood of volunteers following immunization with four kinds of H5N1 virus that have been stocked as pre-pandemic vaccines to be used for future H5N1 virus pandemics
Summary
Since the direct bird-to-human transmission of highly pathogenic avian influenza (HPAI) H5N1 virus occurred in Hong Kong in 1997, such viruses have spread to countries in Asia, the Middle East, Africa, and Europe [1]. It has been estimated that such a pandemic could result in the deaths of up to 350 million people while affecting many more, causing disruption to healthcare systems, the world economy, and society at large [3]. This estimation was based on the following assumption. The human fatality rate of HPAI has been estimated to be around 60%
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
