1. 14/02/13 Pertactin-negative B. pertussis isolates discovered in US | Pediatrics
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Pertactin-negative B. pertussis isolates discovered
in US
Queenan AM. N Engl J Med. 2013; doi: 10.1056/NEJMc1209369.
February 14, 2013
Eleven of 12 isolates of Bordetella pertussis tested by Western blotting in one area of the
United States did not show pertactin, according to a report published online.
Anne Marie Queenan, PhD, of Janssen Research and Development, Raritan, N.J., and
colleagues said that they believe their report was the first one showing pertactin-negative
variants of B. pertussis in the United States. However, data from other countries have shown
similar trends, including France, Finland and Japan.
“Sequencing revealed that in four of these isolates, the insertion sequence (IS) 481 disrupted
the pertactin coding region and that in seven isolates there was a stop codon truncating the
protein,” the researchers wrote in a letter to the editor in a recent New England Journal of
Medicine. The letter was co-authored by Pamela K. Cassiday, MS, from the CDC and Alan
Evangelista, PhD, from St. Christopher’s Hospital for Children, Philadelphia.
Queenan and colleagues said that because their isolates were only recorded in one part of
the country – Philadelphia during 2010 and 2011– more data are needed from other US
regions. This would help determine if this finding is a local event or represents a widespread
shift in B. pertussis strains.
“An understanding of the epidemiology and virulence of pertactin-negative variants is crucial
to developing the next generation of pertussis vaccines,” the researchers concluded.
Disclosure: Queenan reports no relevant financial disclosures.
PERSPECTIVE
This letter by Queenan and colleagues describing gene
variants in B. pertussis isolates is intriguing. As described in this
report, they cultured 12 B. pertussis isolates and found that 11
of the 12 isolates did not express the pertactin protein, which is
one of the components of acellular pertussis vaccines. They
then sequenced the pertactin gene from these 12 isolates and
Nicola found that 11 of the 12 had sequence mutations which caused
Klein
the pertactin gene not to be expressed.
As the authors note, there has been concern that B. pertussis has adapted
due to vaccine selection pressure. Pertactin-negative variants have been
identified in Japan, Finland and France. This study now demonstrates that
there are pertactin-negative B. pertussis variants in the United States and
raises the issue that variants may be contributing to ongoing pertussis
epidemics.
However, an important consideration in this report is that of the 12 isolates,
only two derived from patients aged older than 6 months, and seven of the
12 were cultured from infants aged 2 months and younger. As the majority of
these pertactin-negative isolates was obtained from infants too young to
have been vaccinated (or at most had received one dose of acellular
pertussis vaccine), it is not clear from this study whether a pertactin-negative
variant of B. pertussis is more likely to cause disease in unvaccinated or
undervaccinated populations.
In addition, it will be important to understand whether pertactin-negative
variants of B. pertussis are more likely than non-variant isolates of B.
www.healio.com/pediatrics/vaccine-preventable-diseases/news/online/%7B634E7B73-BABF-4CA6-A16C-F6410349A3F7%7D/Pertactin-negative-B-pertussis-is… 1/2

2. 14/02/13 Pertactin-negative B. pertussis isolates discovered in US | Pediatrics
pertussis to cause disease in individuals who have been recently fully
vaccinated with acellular pertussis vaccines and in individuals with waning
immunity to acellular vaccines.
As this study shows, we will need to be vigilant in monitoring for genetic
variants of B. pertussis. At this point, only time will tell what and how much of
an impact pertactin-negative gene variants will have on the persistence of
ongoing pertussis outbreaks.
Nicola Klein, MD, PhD
Co-Director, Kaiser Permanente Vaccine Study Center
Oakland, Calif.
Disclosures: Klein reports no relevant financial disclosures.
www.healio.com/pediatrics/vaccine-preventable-diseases/news/online/%7B634E7B73-BABF-4CA6-A16C-F6410349A3F7%7D/Pertactin-negative-B-pertussis-is… 2/2