• Lot-to-lot consistency: immunogenicity one month post-vaccination:
• Anti-D antibody concentrations, anti-T antibody concentrations, anti-PT antibody concentrations, anti-FHA antibody concentrations, anti-PRN antibody concentrations, anti-poliovirus type 1, type 2 and type 3 antibody titers.
• Non-inferiority: immunogenicity one month post-vaccination:
• Anti-D booster response, anti-T booster response, anti-PT booster response, anti-FHA booster response, anti-PRN booster response, anti-poliovirus type 1, type 2 and type 3 antibody titers
• Safety:
• incidence of increased circumferential swelling at the DTaP-containing vaccine injection site within 4 days after vaccination.

• "Lot-to-lot consistency: immunogenicity one month post-vaccination:
•  Anti-D antibody concentrations, anti-T antibody concentrations, anti-PT antibody concentrations, anti-FHA antibody concentrations, anti-PRN antibody concentrations, anti-poliovirus type 1, type 2 and type 3 antibody titers.
• Non-inferiority: immunogenicity one month post-vaccination:
•  Anti-D booster response, anti-T booster response, anti-PT booster response, anti-FHA booster response, anti-PRN booster response, anti-poliovirus type 1, type 2 and type 3 antibody titers
• Safety:
•  incidence of increased circumferential swelling at the DTaP-containing vaccine injection site within 4 days after vaccination.
• "

• Immunogenicity one month after vaccination:
• Anti-D antibody concentration, anti-T antibody concentration, anti-PT antibody concentration, anti-FHA antibody concentration, anti-PRN antibody concentration, anti-poliovirus type 1, type 2 and type 3 booster response
• Safety:
• Safety and reactogenicity of the study vaccines in all groups during the entire study period

• "Immunogenicity one month after vaccination:
•  Anti-D antibody concentration, anti-T antibody concentration, anti-PT antibody concentration, anti-FHA antibody concentration, anti-PRN antibody concentration, anti-poliovirus type 1, type 2 and type 3 booster response
• Safety:
•  Safety and reactogenicity of the study vaccines in all groups during the entire study period"

"The aims of this trial are to demonstrate the consistency of three manufacturing lots of GSK Biologicals' DTaP-IPV candidate vaccine in terms of immunogenicity and to evaluate non-inferiority of GSK Biologicals' DTaP-IPV vaccine with respect to immunogenicity and safety compared to the control vaccines (separate injections of GSK Biologicals' DTaP vaccine [Infanrix] and Aventis Pasteur's IPV vaccine [IPOL]) when administered as a 5th dose of DTaP and a 4th dose of inactivated poliovirus vaccine in subjects 4 to 6 years of age. Vaccines will be co-administered with the second dose of M-M-RII, which is recommended at this age. Concomitant administration of a US-licensed influenza vaccine will be allowed according to seasonal availability of vaccine and at the discretion of the investigator."

• Investigational groups: 3, each receive one of 3 lots of DTaP-IPV vaccine.
• Control: US-licensed DTaP (Infanrix) + US-licensed IPV (IPOL) vaccines administered in separate injections.
• Two study visits one month apart for a subset of subjects (Safety and Immunogenicity subset) with a blood draw at each visit. All other subjects will have one visit.
• A telephone contact 4-6 days after vaccination for all subjects, a telephone contact 31-38 days after vaccination for the Safety only subset and a telephone contact for all subjects during the extended safety follow-up phase (5 months following the active phase).

• Prophylaxis
• Diphtheria
• Tetanus
• Pertussis
• Poliomyelitis

Inclusion criteria:

• Healthy male or female child between and including 4 and 6 years of age at the time of vaccination.
• Subjects should have received 4 doses of GSK DTaP (primary vaccination course with booster dose in the second year of life) and 3 doses of IPV during the first 2 years of life and vaccination against measles, mumps, and rubella in the second year of life.

Exclusion criteria:

• Use of any investigational or non-registered drug or vaccine other than the study vaccines within 30 days preceding the administration of study vaccines, or planned use during the study period.
• Administration or planned administration of a vaccine not foreseen by the study protocol within 30 days of study vaccination and ending at Day 30.
• Chronic administration or planned administration of immunosuppressants or other immune modifying drugs within six months prior to study vaccination or planned administration during the study period.
• Administration of immunoglobulins and/or blood products within 3 months prior to vaccination or planned administration during the study period.