Pertussis is probably the most prevalent vaccine-preventable disease in Western countries. Estimates of yearly infection frequencies range form 1-6% . In adolescents and adults, pertussis generally follows a mild course. In infants, however, pertussis can be life threatening. In the 1980s and 1990s a resurgence of pertussis, characterized by a shift in disease prevalence towards older age categories, was observed in many countries despite high vaccination coverage. The increase in pertussis may be due to a number of factors, including improved reporting, waning vaccine-induced immunity and pathogen adaptation.Strain typing
Strain typing has played an important role in the study of the causes of persistence and reemergence of pertussis . Such studies have revealed large shifts in B. pertussis populations after the introduction of vaccination and have identified lineages which have a global distribution . Several methods are currently used for typing of B. pertussis including Pulsed-Field Gel Electrophorises (PFGE), Multi-Locus Sequence Typing (MLST) and Multiple-Locus Variable number of tandem repeat Analysis (MLVA) [4, 5]. Of the three, PFGE is the most discriminatory method. However, it is laborious and, most importantly, inter-laboratory comparisons are problematic. In contrast MLST and MLVA are sequence-based and highly portable. B. pertussis is genetically highly homogeneous and this is reflected in a very limited number of MLSTs. Nevertheless, MLST focused on virulence factors has been highly useful to identify escape variants in B. pertussis populations .Multiple-Locus Variable number of tandem repeat Analysis (MLVA) of B.pertussis
MLVA lies between PFGE and MLST with respect to resolving power . The MLVA method used here is based on accurate band sizing using an automated DNA sequencer and was developed by Schouls et al., .Profiles and types For of B. pertussis 6 VNTR loci are used. The B. pertussis MLVA type list contains over 170 distinct MLVA types most of which were obtained from strains collected in Europe . References
1. Berbers GA, de Greeff SC, Mooi FR: Improving pertussis vaccination. HumVaccin
2. Mooi FR, van Loo IH, King AJ: Adaptation of Bordetella pertussis to vaccination: a cause for its reemergence? EmergInfectDis 2001, 7(3 Suppl):526-528.
3. Mooi FR, van Loo IHM, van Gent M, He Q, Heuvelman CJ, Bart MJ, de Greeff SC, Diavatopoulos DA, Teunis PF, Nagelkerke NJ et al: Bordetella pertussis Strains with Increased Toxin Production Associated with Pertussis Resurgence. Emerg Infect Dis 2009, 15(8):1206-1213.
4. Mooi FR, Hallander H, Wirsing von Konig CH, Hoet B, Guiso N: Epidemiological typing of Bordetella pertussis isolates: recommendations for a standard methodology. EurJ ClinMicrobiolInfectDis 2000, 19(3):174-181.
5. Schouls LM, van der Heide HG, Vauterin L, Vauterin P, Mooi FR: Multiple-locus variable-number tandem repeat analysis of Dutch Bordetella pertussis strains reveals rapid genetic changes with clonal expansion during the late 1990s. JBacteriol 2004, 186(16):5496-5505.
6. He Q, Mertsola J: Factors contributing to pertussis resurgence. FutureMicrobiol 2008, 3:329-339.
7. Advani A, Van der Heide HG, Hallander HO, Mooi FR: Analysis of Swedish Bordetella pertussis isolates with three typing methods: characterization of an epidemic lineage. J Microbiol Methods 2009, 78(3):297-301.
8. van Amersfoorth SC, Schouls LM, van der Heide HG, Advani A, Hallander HO, Bondeson K, vonKonig CHW, Riffelmann M, Vahrenholz C, Guiso N et al: Analysis of Bordetella pertussis Populations in European Countries with Different Vaccination Policies. JClinMicrobiol 2005, 43(6):2837-2843.
Protocol and tables for data analysis.
A number of files that may be useful if you want to perform MLVA can be downloaded here. These files may be updated if alterations in the protocol or allele tables have been made.
- Protocol_MLVA_Bpertussis.pdf A detailed protocol for the MLVA scheme containing details on the reagents, primers
- Bpertussis MLVA type table A file will open containing all currently known MLVA types, complexes and profiles (in CSV format) Attention : Due to appearance of half repeats in VNTR4, those repeats will be assigned the same allenumber with a 5 added, so allele 7,5 will become 75 ! This is neccesary in order to keep the typing tool functional.
- Bpertussis_MLVA_allele_size_table.xls A file containing the theoretical size of all currently known alleles.
- SGPanel_BPVNTR1_LIZ500.xml Panel file for use with the GeneMarker software. This file contains all allele sizes and their bin sizes and is used to assign the number of repeats in the VNTRs amplified in multiplex 1.
- SGPanel_BPVNTR3_LIZ500.xml Panel file for use with the GeneMarker software. This file contains all allele sizes and their bin sizes and is used to assign the number of repeats in the VNTRs amplified in multiplex 3.
- SGPanel_BPVNTR4_LIZ500.xml Panel file for use with the GeneMarker software. This file contains all allele sizes and their bin sizes and is used to assign the number of repeats in the VNTRs amplified in multiplex 4.
- SGPanel_BPVNTR5_LIZ500.xml Panel file for use with the GeneMarker software. This file contains all allele sizes and their bin sizes and is used to assign the number of repeats in the VNTRs amplified in multiplex 5.
- SGPanel_BPVNTR6_LIZ500.xml Panel file for use with the GeneMarker software. This file contains all allele sizes and their bin sizes and is used to assign the number of repeats in the VNTRs amplified in multiplex 6.
- SGSize_LIZ500.xml Size standard file for use with the GeneMarker software.
- Bpertussis_MST.pdf Minimum spanning tree based on MLVA profiles.
If you discover a new allele or MLVA type please which you would like to be added to the list please contact Han van der Heide.