AU: Whooping cough vaccine may have lost its punch as bacterium evolves

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Source: http://www.theguardian.com/world/201...terium-evolves


Whooping cough vaccine may have lost its punch as bacterium evolves
Australian study showed 80% of cases were free of the protein needed for vaccine's efficacy
Australian Associated Press
theguardian.com, Tuesday 15 April 2014 06.31 BST

The vaccine used to immunise against whooping cough might have bred a more evolved strain of the disease.

Researchers from the University of NSW say Bordetella pertussis, the bacterium that causes the potentially deadly illness, appears to have evolved to overcome the vaccine used to fight it.

That vaccine works by locating a protein called pertactin, which had been identified as one of the key elements of the disease.

But the study showed that about 80% of Australian whooping cough cases in 2012 were pertactin-free...

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Re: AU: Whooping cough vaccine may have lost its punch as bacterium evolves

Volume 20, Number 4?April 2014
Research
Rapid Increase in Pertactin-deficient Bordetella pertussis Isolates, Australia


Connie Lam, Sophie Octavia, Lawrence Ricafort, Vitali Sintchenko, Gwendolyn L. Gilbert, Nicholas Wood, Peter McIntyre, Helen Marshall, Nicole Guiso, Anthony D. Keil, Andrew Lawrence, Jenny Robson, Geoff Hogg, and Ruiting LanComments to Author
Author affiliations: University of New South Wales, Sydney, New South Wales, Australia (C. Lam. S. Octavia, L. Ricafort, R. Lan); University of Sydney, Sydney (V. Sintchenko, G.L. Gilbert); Westmead Hospital, Sydney, (V. Sintchenko, N. Wood, P. McIntyre); University of Adelaide, Adelaide, South Australia, Australia (H. Marshall); Institut Pasteur, Paris, France (N. Guiso); Princess Margaret Hospital for Children, Perth, Western Australia, Australia (A.D. Keil); Women?s and Children?s Hospital, Adelaide (A. Lawrence); Sullivan Nicolaides Pathology, Brisbane, Queensland, Australia (J. Robson); University of Melbourne, Parkville, Victoria, Australia (G. Hogg)

Suggested citation for this article
Abstract

Acellular vaccines against Bordetella pertussis were introduced in Australia in 1997. By 2000, these vaccines had replaced whole-cell vaccines. During 2008?2012, a large outbreak of pertussis occurred. During this period, 30% (96/320) of B. pertussis isolates did not express the vaccine antigen pertactin (prn). Multiple mechanisms of prn inactivation were documented, including IS481 and IS1002 disruptions, a variation within a homopolymeric tract, and deletion of the prn gene. The mechanism of lack of expression of prn in 16 (17%) isolates could not be determined at the sequence level. These findings suggest that B. pertussis not expressing prn arose independently multiple times since 2008, rather than by expansion of a single prn-negative clone. All but 1 isolate had ptxA1, prn2, and ptxP3, the alleles representative of currently circulating strains in Australia. This pattern is consistent with continuing evolution of B. pertussis in response to vaccine selection pressure.

full article

http://wwwnc.cdc.gov/eid/article/20/4/13-1478_article.htm