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Welcome to the Multiple-Locus Variable number tandem repeat Analysis home page

Multiple-Locus Variable number tandem repeat Analysis (MLVA) is a method used to perform molecular typing of particular microorganisms. It utilizes the naturally occurring variation in the number of tandem repeated DNA sequences found in many different loci in the genome of a variety of organisms. The method originates from forensic science where it is used for DNA fingerprinting in samples from human origin. MLVA is also widely used to assess the molecular fingerprint of micro-organisms such as bacteria. The molecular typing profiles are use to study transmission routes, to assess sources of infection and also to assess the impact of human intervention such as vaccination and use of antibiotics on the composition of bacterial populations.

MLVA method
In MLVA the number of repeats in a set of VNTR loci is assessed. For the bacterial species presented here this is achieved by performing PCR of the VNTR loci followed by accurate sizing of the PCR products on an automated DNA sequencer. The assessed product size is used to calculate the number of repeat units in each locus. The calculated numbers of repeats of the VNTR loci (alleles) are combined into a string which consists of integers e.g. 14-0-2-4-1-7-1-6 and is referred to as the MLVA profile. Each unique MLVA profile is given a MLVA type designation e.g. MT0021. The MLVA profile can be used for comparison and clustering and often complex assignments can be made. The unambiguous assessment of the number of repeats results in numerical data that can easily be compared to those in central databases via the Internet.

MLVA typing tool
The typing tool for the MLVA will allow interrogation of a MLVA type table by typing in a MLVA allelic profile. The tool will report the MLVA type belonging to this profile and depending on the database it will also display the MLVA complex to which this MLVA type belongs. The tool can be set to report the exact and closest matching profiles.
If you find a new profile of a particular species and would like to add the new profile to type table you are encouraged to send your trace files or a lysate of your isolate to our institute. We will then check the profile and if we confirm this is a new profile we will assign a new MLVA type and add the profile to the type table.