The “Protective Agent” Inside Virus Transport Tubes – Huachenyang Dissects the Core-Formulation Logic of Its Transport Medium

During respiratory-virus season or on the front line of an outbreak, the slim plastic tube you toss into a bio-waste bag is the pivot between a true result and a false one.
The critical component is not the polypropylene shell but the few millilitres of liquid inside—the virus transport medium (VTM) and, above all, its protective agent.
Huachenyang, a manufacturer that has spent fifteen years refining VTM chemistry, explains why this “invisible ingredient” is the real guardian of assay accuracy.

1. The four missions of a VTM protective agent

1.1 Shields viral nucleic acids
Once the swab leaves the patient, cellular RNases and DNases attack RNA and DNA within minutes.
A high-quality protective agent chelates divalent cations (Mg²⁺, Ca²⁺) or adds broad-spectrum nuclease inhibitors, preventing degradation and the false negatives that follow.

1.2 Keeps microbial competitors out
Environmental and commensal bacteria/fungi love warm, protein-rich media.
Safe, low-interference antibiotics/antimycotics suppress their growth, stopping both consumption of the target virus and release of bacterial DNA that can cloud qPCR curves.

1.3 Preserves viral structure & infectivity
For culture or antigen assays the virus must remain intact and infectious.
Iso-osmotic buffers (Hank’s, Tris) plus stabilisers such as trehalose or BSA form a molecular “air-bag” that minimises pH drift and freeze-thaw damage during bumpy logistics.

1.4 Covers non-ideal logistics
Not every clinic has a cold chain.
Huachenyang’s formulation keeps RNA detectable for 72 h at 25 °C—50 % longer than the usual 48 h spec—buying extra time for rural or surge shipments.

2. The four-component synergy behind the formula

All percentages are optimised for molecular assays (no Ct shift vs fresh sample) yet non-toxic for cell culture when the same tube is used for isolation.

3. Huachenyang technical edge

• Temperature-robust version validated in accelerated (45 °C, 7 d) and real-time (25 °C, 72 h) studies; RNA recovery ≥95 %.
• PCR-compatible preservatives—no inhibition of internal control up to 1:10 template dilution.
• Data-driven release: every lot must pass ≥95 % detectability of spiked 200-copy/µL SARS-CoV-2 RNA after 72 h at 25 °C.

Take-home message
The protective agent is the silent gatekeeper between bedside and bench.
A scientifically formulated, data-verified VTM turns “sample in, result out” from a gamble into a guarantee.

We are a manufacturer of flocked swabs, Huachenyang. Please feel free to contact us. We manufacture various types of flocked swabs in our factory.