Genetically Modified Pertussis Vaccine Produces Lasting Response

By Reuters Staff

NEW YORK (Reuters Health) - Monovalent and combined acellular pertussis vaccines made with genetically inactivated toxin produce a stronger and more sustained antibody response than those containing chemically inactivated toxin, a new phase 2/3 trial shows.

"Genetically inactivated acellular pertussis vaccines licensed for immunization of children aged 11 years and older and of adults could be advantageous in enabling maternal immunization earlier in or before pregnancy and could address the fast-waning immunity of pertussis vaccines in adolescents," Dr. Punnee Pitisuttithum of Mahidol University in Bangkok and colleagues write in The Lancet Infectious Diseases, online September 25.

Acellular pertussis vaccines produce a smaller, shorter-term antibody response than whole-cell pertussis vaccines, the authors note, but they are now more widely used given their lower risk of systemic side effects. "Thus, acellular pertussis vaccines that can provide longer-lasting immune protection in children and adults are needed," they add.

While chemical inactivation alters the structure of pertussis toxin, weakening antibody binding and response, "genetic inactivation with recombinant DNA technologies maintains the toxin's native epitopic structure and immunogenic properties," they add.

The current study is a one-year follow-up of a phase 2/3 trial in which 450 participants were randomized to receive a vaccine containing genetically inactivated pertussis toxin (PTgen) plus filamentous hemagglutinin (FHA); a multivalent vaccine containing PTgen along with tetanus and reduced-dose diphtheria toxoids; or reduced-dose chemically inactivated pertussis toxin (PTchem).

Based on data from 442 participants, seroconversion rates for pertussis-toxin-neutralizing antibodies at one year were 76% for the monovalent PTgen vaccine, 81% for the multivalent PTgen vaccine and 8% with reduced-dose PTchem.

Participants who received a vaccine containing PTgen were also far more likely to seroconvert for IgG antibodies to pertussis toxin and FHA.

During follow-up, five women became pregnant, with no maternal or neonatal complications.

Thailand has licensed the vaccine for immunization of adults and children 11 and older.

"Lack of a commercially available monovalent pertussis vaccine (without tetanus and diptheria toxoids) is cited by parents and providers as one barrier to high uptake of pertussis vaccination in pregnancy, and evidence from baboon studies supports antibody to pertussis toxin alone being protective," Dr. Peter B. McIntyre of the University of Sydney, Australia, and Dr. Kathryn M. Edwards of Vanderbilt University in Nashville, Tennessee, write in an editorial accompanying the study.

"Thus, a monovalent pertussis vaccine containing PTgen that generates long-lasting high titres of pertussis toxin neutralising antibodies has the potential to improve protection against severe pertussis disease in neonates in the first 6 weeks of life," they add.

BioNet-Asia funded the study.

SOURCE: https://bit.ly/2Ofd9r4 and https://bit.ly/2y8KgTp

Lancet Infect Dis 2018.

(c) Copyright Thomson Reuters 2018. Click For Restrictions - https://agency.reuters.com/en/copyright.html

For more Pharmacy Learning Network articles, visit the homepage

To learn about Pharmacy Learning Network Live meetings, click here