Maximize Your Virus Detection Potential with the Right Viral Transport Media

Viral transport media (VTM) are nutrient solutions that are used to carry and preserve virus samples from the collection site to the laboratory for testing and identification. VTMs are essential for virus detection because they help maintain the viability and integrity of the virus particles, which are more sensitive and unstable than other microorganisms. The choice and use of the right VTM can affect the quality and accuracy of the virus detection results. In this article, we will provide some tips on how to select and apply the appropriate VTM for different types of virus samples.

I. Consideration Factors

When choosing a VTM for virus detection, there are several factors to consider, such as:

The type and stability of the virus

Different viruses have different characteristics and requirements for survival and growth. Some viruses are more resistant to environmental changes and can be transported in simple solutions like saline or phosphate-buffered saline (PBS). Other viruses are more fragile and need specific additives or inhibitors to prevent degradation or contamination. For example, RNA viruses like influenza or coronavirus are more prone to degradation by RNases and need a VTM that contains guanidine thiocyanate or other stabilizers.

The type and size of the specimen

The specimen refers to the material that contains the virus, such as nasal swabs, throat swabs, sputum, blood, urine, etc. The type and size of the specimen can affect the amount and quality of the virus particles that can be extracted and detected. The VTM should be compatible with the specimen type and size and should not interfere with the extraction or detection methods. For example, some VTMs may contain substances that can inhibit PCR or other molecular assays.

The storage and transport conditions

The storage and transport conditions

The storage and transport conditions refer to the temperature, humidity, light exposure, duration, and distance of the specimen from the collection site to the laboratory. The storage and transport conditions can affect the viability and integrity of the virus particles and thus affect the detection results. The VTM should be able to protect the virus particles from adverse environmental factors and maintain their optimal conditions for survival and growth. For example, some VTMs may require refrigeration or freezing while others may be stable at room temperature.

The availability and cost of the VTM

The availability and cost of the VTM refer to the supply and demand of the VTM in the market and the budget of the user. The availability and cost of the VTM can affect the accessibility and affordability of virus detection for different users and settings. The VTM should be readily available and affordable for the user without compromising its quality and performance. For example, some VTMs may be more expensive or scarce due to high demand or limited production while others may be cheaper or more abundant due to low demand or mass production.

II. Types of Viral Transport Media

There are different types of VTMs available for virus detection, such as:

Universal transport media (UTM)

UTM is a collection and transport system that can be used for a variety of viruses, chlamydia, mycoplasma, and ureaplasma organisms1. UTM contains Hanks’ balanced salt solution (HBSS) enriched with proteins, sugars, antibiotics, antimycotics, and a pH indicator2. UTM can preserve the specimens for up to 72 hours at room temperature or up to 30 days at 4°C1. The advantages of UTM are its versatility, compatibility with molecular assays, and long-term storage. The disadvantages of UTM are its high cost and limited availability due to high demand.

Viral culture media (VCM)

VCM is a collection and transport system that can be used for viruses that require cell culture for isolation and identification. VCM contains cell culture media supplemented with fetal bovine serum (FBS), antibiotics, antimycotics, and buffers. VCM can preserve the specimens for up to 48 hours at 4°C or up to 7 days at -70°C. The advantages of VCM are its suitability for cell culture and its low cost. The disadvantages of VCM are its incompatibility with molecular assays and its short-term storage.
Saline or phosphate-buffered saline (PBS)Saline or PBS is a simple solution that can be used for viruses that are stable and resistant to environmental changes. Saline or PBS contains sodium chloride or sodium phosphate and water. Saline or PBS can preserve the specimens for up to 24 hours at room temperature or up to 7 days at -70°C. The advantages of saline or PBS are its simplicity, availability, and affordability. The disadvantages of saline or PBS are its unsuitability for fragile viruses and its interference with some extraction or detection methods.

Other specialized media (e.g. M4, M5, M6)

These are collection and transport systems that can be used for specific viruses that have special requirements for survival and growth. These media contain different additives or inhibitors that can enhance the stability or prevent the degradation of the virus particles. These media can preserve the specimens for different durations depending on the type of virus and the storage conditions. The advantages of these media are their specificity, efficacy, and compatibility with molecular assays. The disadvantages of these media are their scarcity, complexity, and expense.

The DSK-F10-96A kit boasts several benefits, such as ease of use, secure sample transportation, and compatibility with multiple diagnostic tests. The flocked swab's open fiber structure enables superior sample elution, enhancing assay sensitivity and overall accuracy. Additionally, the kit is devoid of PCR inhibitors, ensuring its compatibility with various diagnostic tests.

III. Tips for Correct and Safe usage

Here are some detailed tips on how to use a VTM correctly and safely:

Follow the manufacturer’s instructions and expiration date: Different manufacturers may have different formulations and specifications for their VTM products. You should always follow the instructions provided by the manufacturer and check the expiration date before using them3. For example, some VTM products may require refrigeration before use, while others may be stored at room temperature. Some VTM products may also have different volume requirements or additives for different types of specimens. You should read the product label carefully and follow the directions accordingly.

Use sterile swabs and tubes: To avoid contamination and ensure accurate results, you should use sterile swabs and tubes for collecting and transporting specimens. Do not touch the tip of the swab or the inside of the tube with your hands or any other objects2. You should also use appropriate swabs for different types of specimens, such as nasopharyngeal swabs for respiratory specimens or genital swabs for urogenital specimens. You should insert the swab into the specimen site and rotate it gently for a few seconds to collect enough material. Then you should place the swab into the tube containing VTM and break off or cut off the excess part of the swab. You should secure the cap tightly and invert the tube several times to mix the specimen with VTM.

Label the specimens clearly and accurately: You should label each specimen with a unique identifier, such as a barcode or a number, and include relevant information such as patient name, date of birth, date and time of collection, type of specimen, etc. This will help to avoid mix-ups and errors in testing2. You should also use waterproof labels or markers to prevent smudging or fading. You should attach the label to the side of the tube, not to the cap or over any other information on the tube.

Keep the specimens refrigerated or frozen until testing: VTM can maintain organism viability for 48 hours at room or refrigerated temperature. However, if testing is delayed beyond 48 hours, you should freeze the specimens at -70°C or lower until testing12. You should also avoid repeated freezing and thawing cycles as this may affect organism viability. You should transport frozen specimens on dry ice or in insulated containers to prevent thawing during transit.

Dispose of the used materials properly: You should follow your local guidelines and regulations for disposing of biohazardous waste. You should wear gloves and other protective equipment when handling used materials and dispose of them in appropriate containers2. You should also disinfect any surfaces or equipment that may have come into contact with VTM or specimens using bleach or alcohol solutions.

IV. Cost and Formulation of Viral Transport Media

The cost and formulation of VTM are vital factors to consider as they directly impact the efficiency and accuracy of viral diagnostics, as well as the overall budget allocation for healthcare facilities and diagnostic laboratories.

The formulation of VTM involves the careful selection of components that support the preservation of the virus while inhibiting bacterial and fungal contamination. The primary constituents of a typical VTM include a balanced salt solution, buffering agents, proteins, and antimicrobial substances. The balanced salt solution provides an isotonic environment to maintain viral integrity, while buffering agents, such as HEPES or phosphate buffers, help stabilize the pH during transport and storage. Proteins, such as bovine serum albumin or gelatin, serve as stabilizers, protecting the virus from degradation or denaturation. Antimicrobial substances, like antibiotics and antifungal agents, are included to prevent the overgrowth of contaminating microorganisms.

One cost-effective alternative is the in-house preparation of VTMs by healthcare facilities and diagnostic laboratories. By sourcing and purchasing raw materials in bulk, these institutions can significantly reduce the cost per unit of VTM, which can be particularly beneficial for large-scale diagnostic efforts, such as during a pandemic. Moreover, in-house preparation allows for better control over the quality and consistency of the VTM, tailoring it to the specific needs of the laboratory or facility.

Collaborative efforts among healthcare facilities, diagnostic laboratories, and research institutions are essential to share knowledge, experiences, and best practices in VTM formulation and cost reduction. By pooling resources and expertise, these stakeholders can develop innovative solutions and more efficient VTMs to ensure accurate and reliable viral diagnostics.
Here are some formulations of commonly used viral transport medium:

Amies Transport Medium

Amies Transport Medium is a widely used and effective semisolid medium for the transportation of swab specimens to the microbiology laboratory. It is designed for the collection, transport, and preservation of bacterial specimens, particularly aerobic, anaerobic, and facultative anaerobic microorganisms. Amies medium is a modification of Stuart's medium, in which glycerophosphate is replaced by an inorganic phosphate buffer.

Formulation: (g/L)

Cary-Blair Transport Medium

Cary-Blair Transport Medium is a specialized transport medium developed by Cary and Blair in 1964 for the transport of fecal specimens. It is particularly useful for the preservation and transport of enteric pathogens, such as Shigella, Salmonella, Vibrio cholerae, and Escherichia coli O157:H7. The medium has a low nutrient content, a low oxidation-reduction potential, and a high pH, making it suitable for maintaining the viability of Vibrio cultures for an extended period.

Formulation: (g/L)

Stuart Transport Medium

Stuart Transport Medium is a non-nutritional, semi-solid substrate designed for the transport and maintenance of fastidious, pathogenic organisms, particularly Neisseria species and other fastidious microorganisms. It was originally described by Moffett et al. and Stuart et al. and has been widely used for transporting clinical swab samples since its invention by Dr. R.D. Stuart.

Formulation(without activated carbon): (g/L)

Formulation(with activated carbon): (g/L)

V. Conclusion

selecting the right viral transport media is crucial for maximizing your virus detection potential and ensuring accurate and reliable diagnostic results. By understanding the key factors, such as the media's composition, stability, and compatibility with various testing platforms, laboratories and healthcare professionals can make informed decisions when choosing the most suitable transport media. As we continue to face new viral threats, investing in high-quality transport media will not only help streamline the diagnostic process but also contribute significantly to effective disease surveillance, control, and prevention efforts. Ultimately, the right viral transport media will play a pivotal role in safeguarding public health and enabling a swift response to future pandemics.

Want to learn more about our viral transport medias?

Mantacc offers a wide range of dependable VTMs including Amies, Stuart and Cary-blair. Need something specific? Our expert customization service is here to help. Click the link to explore our viral transport media collection or contact our sales team by clicking on the image below.