The sample preservation principle of the virus transportation system is mainly realized through various components in the preservation solution and a specific physical and chemical environment. The following is a detailed introduction:

The preservation solution usually contains buffering substances, such as phosphate buffer solution. Its function is to maintain the stability of the acidity and alkalinity of the sample’s environment. Viruses can maintain a stable structure and viability within a specific pH range. Generally, the suitable pH value for most viruses is between 7.2 and 7.4. If the pH value is too high or too low, it may lead to the denaturation of viral proteins and the breakage of nucleic acids, thus inactivating the virus. Buffering substances can resist changes in the pH value caused by external factors and provide a relatively stable acid-base environment for the virus.

The electrolyte and other solute components in the preservation solution can regulate the osmotic pressure to make it isotonic with the intracellular environment of the virus sample. An isotonic environment is crucial for preventing cell rupture or shrinkage. If the osmotic pressure of the preservation solution is too high, the cells will lose water and shrink, causing the virus released from the cells to possibly be inactivated due to the environmental change. Conversely, if the osmotic pressure is too low, the cells will absorb water, swell, and even rupture, which will also affect the integrity and viability of the virus. By maintaining an isotonic state, it can ensure that the virus is in a relatively stable physical environment, whether inside or outside the cell, which is conducive to maintaining its viability.

The preservation solution often contains components such as antibiotics and antibacterial agents, such as penicillin and streptomycin. These substances can inhibit the growth and reproduction of bacteria, fungi, and other microorganisms. During the sample collection and preservation process, it is inevitable that some miscellaneous bacteria will be mixed in. If not inhibited, these microorganisms will multiply rapidly in the preservation solution. They will consume nutrients, produce metabolic waste, change the composition and environment of the preservation solution, and thus affect the viability of the virus. Antibacterial components can effectively kill or inhibit the growth of miscellaneous bacteria, ensuring the purity of the preservation solution and creating favorable conditions for virus preservation.

The preservation solution may contain some protective agent components, such as bovine serum albumin (BSA), gelatin, sucrose, etc. These protective agents can form a protective film on the surface of the virus particles, preventing the mutual aggregation and precipitation of the virus particles and also resisting the damage to the virus structure caused by external physical and chemical factors. For example, BSA can bind to the proteins on the surface of the virus, playing a role in stabilizing the virus structure. Sugars such as sucrose can lower the freezing point of water under low-temperature conditions, reducing the formation of ice crystals and avoiding the damage of ice crystals to the virus structure.

Some preservation solutions will add antioxidants, such as vitamin C, glutathione, etc. The nucleic acids and proteins of viruses and other components are easily affected by oxidation and undergo denaturation or degradation. Oxidation reactions may lead to the breakage of the viral nucleic acid chain and the oxidative modification of amino acid residues in proteins, etc., thus making the virus lose its activity. Antioxidants can capture free radicals and prevent the occurrence of oxidation reactions, protecting the biological macromolecules such as the nucleic acids and proteins of the virus from oxidative damage and prolonging the survival time of the virus in the preservation solution.

In addition to the function of the preservation solution, the virus transportation system usually also comes with corresponding temperature and humidity control measures. Generally, virus samples need to be stored under specific temperature conditions, and common ones include room temperature (usually 20°C – 25°C), refrigeration (2°C – 8°C), or freezing (-20°C, -80°C or even lower). An appropriate temperature can reduce the metabolic activities of the virus and slow down the decay rate of the virus. At the same time, controlling the appropriate humidity is also very important. Too high humidity may lead to the growth of microorganisms, and too low humidity may cause the sample to dry out, affecting the viability of the virus. By using thermal insulation materials, cold chain equipment, and humidity adjustment devices, etc., a suitable temperature and humidity environment is created for the virus samples, further ensuring the preservation effect of the samples.