Viral Transport Media (VTM)- Principle, Preparation, Uses, Limitations


A viral transport media (VTM) is a nutrient substance used to carry and maintain the viability of specimens (viruses) to a laboratory for the identification and further processing of the sample. Transport media for viruses are especially important as they are more labile than other infectious agents.

The probability of successful isolation increases when the time interval between collection and inoculation of the culture is less and when the specimen contains as many virus particles as possible.

In order to maximize the amount of virus in the specimen, the sample collection should be done early in the patient’s illness.

Successful and reliable isolations of viruses can be accomplished when a suitable transport medium is used.

The isolation count also increases when viral specimens are sent to either a local laboratory or a reference laboratory.

VTMs are prepared with the idea of providing appropriate conditions of temperature, pH, and nutrients.

The constituents of an appropriate viral transport media are selected to create an isotonic solution containing proteins to protect the viral structure, antibiotics to control microbial contamination, and one or more buffers to control the pH.

VTMs are prepared with the idea of sustaining the viability of the viral culture or specimens for tests like the nucleic acid amplification test (NAAT) while preventing the drying of the sample.