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· Diphtheria-tetanus-acellular pertussis (DTPa) vaccines have also ensured continued high level disease protection in these countries following the shift from Pw- to Pa-containing vaccines, and allowed pertussis booster programs to be implemented. Vaccines containing between one and five components have been licensed and implemented. Those with three or more components consisting of filamentous hemagglutinin (FHA), pertussis toxin (PT) and pertactin (PRN) are considered to be more effective than one/two-component Pa vaccines that contain only PT or both PT and FHA. Data obtained from a DTPa5 vaccine containing FIM2 and FIM3 have indicated a shift towards an increase in FIM3-expressing B. pertussis clinical breakthrough cases when compared with control vaccine. By contrast, relatively minor PT and PRN sequence polymorphisms have been identified adsorption of PRN to aluminum salt appears critical for optimal protective capacity in pertussis lung challenge.
· In addition, clinical studies have shown anti-PRN antibody levels to be higher when PRN is adsorbed.The available data, therefore, demonstrate that appropriately formulated acellular vaccines containing PT and PRN are the preferred option for pertussis immunization. ( 1 )
· In several countries pertussis is re-emerging, despite a high vaccination coverage. It is suggested that antigenic divergence between Bordetella pertussis vaccine strains and circulating strains, in particular with respect to pertactin, has contributed to pertussis re-emergence. Moreover, passive and active immunization indicated that region 1 confers protective immunity. An mAb directed against a linear conserved epitope conferred cross-immunity against isolates with distinct pertactin variants. The results indicate an important role of region 1 of pertactin in immunity. ( 2 )
REFERENCES:
1. Acellular pertussis vaccines and the role of pertactin and fimbriae.
Poolman JT, Hallander HO. Expert Rev Vaccines. 2007 Feb;6(1):47-56
2. Role of the polymorphic region 1 of the Bordetella pertussis protein pertactin in immunity
Audrey J. King1,4, Guy Berbers2, Hans F. L. M. van Oirschot1, Peter Hoogerhout3, Karen Knipping2 and Frits R. Mooi1,4 Microbiology (2001), 147, 2885-2895.
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The preventive healthcare in paediatrics is forever innovating and newer and better modalities are available to the clinician. The clinician though is regularly bombarded by marketing jargon and only exposed to half-baked information from the various sources. This has led to more confusion and
improper utilization of available products. The scientific CME's has always been in the forefront of updating the clinician with recent advances and developments in this sector. In-spite of this, the percolation of scientific information and guidelines have always been confusing and mixed.
The most recent in the series has been the launch and science related to the acellular pertussis vaccine. The pediatrician should dissect the depth of the issue and subvert a long and avoidable crisis in the immunization of the
generation next.
A few debatable points that may be considered would concern
1. Importance of various components in the vaccine?
2. Importance of pertactin presence or absence in any vaccine?
3. Re-emergence of Hib disease ever since acellular vaccine has been advocated in the west?
4. Increase in clinical and symptomatic cases of para-pertussis in adolescents and adults?
5. Withdrawal of 2 component vaccine in the west and introduction of the same in INDIA?
It would be of prime importance that all available scientific data is well examined and all pediatricians across India are informed of the most suitable vaccine for vaccinating our infants in future. The guidelines would also help simplifying the schedule,which would reduce the existing and
"unknown confusion" amongst practicing pediatricians.
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