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SUMMARY:Prophylactic HPV Vaccines:  Where are we now! - Professor Margaret
  Stanley\, Department of Pathology\, University of Cambridge
DTSTART:20070117T163000Z
DTEND:20070117T173000Z
UID:TALK6117@talks.cam.ac.uk
CONTACT:4872
DESCRIPTION:The ability to generate human papillomavirus (HPV) virus like 
 particles (VLPs) by the synthesis and self-assembly in vitro of the major 
 virus capsid protein L1 has transformed our prospects for preventing cervi
 cal carcinoma in women.  Immunisation with L1 VLPs provides type specific 
 protection in all the animal infections so far tested.  In Phase I trials 
 in humans HPV L1 VLP vaccines are safe and highly immunogenic stimulating 
 robust B and T cell responses and generating high titres of neutralising a
 ntibody.  In the Phase II and III trial antibody levels persist at measura
 ble levels for at least 48 months post vaccination suggesting that strong 
 immune memory is generated.  At present the assumption is that the protect
 ion achieved by these vaccines against incident HPV infection and HPV asso
 ciated ano-genital pathology is mediated via serum neutralising IgG.  Howe
 ver\, since there have been no vaccine failures thus far\, immune correlat
 es of protection have not been established.  The available evidence is tha
 t the immunodominant neutralising antibodies generated in natural infectio
 ns are type-specific and are not cross-neutralising although highly homolo
 gous HPV pairs share minor cross- neutralisation epitopes. Cross reactive 
 and cross neutralising antibodies are generated in HPV L1 vaccinees but at
  significantly lower titres and the duration of any cross protection that 
 might be elicited is uncertain.  L1 VLP vaccines are prophylactic not ther
 apeutic vaccines and for maximal population effectiveness should be delive
 red before the sexual debut to pre-pubertal females (or males) and social 
 and cultural issues may be important in determining vaccine takeup. 
LOCATION:Lecture Theatre 1\, Department of Veterinary Medicine
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