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