When a viable virus culture must be shipped, the available options will depend on national and international regulations. For intra-country shipments between laboratories, a live culture (in a cell culture tube or flask) shipped at room temperature may be an acceptable option. The alternative is to ship an aliquot of frozen virus stock (lysate). Shipment of the frozen lysate requires less processing by the sender and the receiver, but dry ice must be available, and the cost of a dry ice shipment may be prohibitive. Refer to Annex 5.2 for detailed instructions on the preparation of virus stocks.
A flask of Vero/hSLAM cells must be precisely timed to be ready when the shipment is arranged, and advance notification and coordination with the recipient is critical. An aliquot of the virus isolate is used to infect Vero/hSLAM cells that have been seeded into a 25cm2 tissue culture flask. The cells should be infected when the cell monolayer is 50-75% confluent (and incubated for the full inoculation period) just prior to shipment. Refer to Annex 5.2 for detailed protocols for inoculation and propagation of cell culture.
Prior to shipment, MEM or DMEM (plus antibiotics and 2% FBS) is added to the flask of infected Vero/hSLAM cells. The flask should be filled with the medium, leaving some space at the neck of the flask (~0.5ml) to allow for liquid expansion during shipping. The top of the flask should be screwed on tightly and sealed with parafilm (or other similar product, but not sticky tape). Sufficient absorbent material should be wrapped around the flask to absorb the entire liquid contents of the flask, should the flask become damaged. The flask and absorbent material is placed in a leak-proof container such as a zip-lock plastic bag. The sealed bag or container is then placed inside a leak-proof outer container that meets the United Nations Packing Instruction 620 standard for packaging and documentation and the package is shipped at room temperature.
An overview of the requirements of the packaging and shipping containers for Category A infectious substances is provided in Chapter 3. Clinical specimens for the laboratory diagnosis and molecular epidemiology of measles, rubella, and CRS, section 3.1, Guidelines for the preparation and transport of clinical specimens. However, because shipping regulations and labelling instructions may be subject to modification, the publication prepared by WHO (Guidance on Regulations for the Transport of Infectious Substances) [5], or most current update, should be consulted.
If a viable virus culture is not required, viral lysates or viral RNA extract can be applied to FTA® Cards, which can then be transferred to another laboratory. Chemicals impregnated in the paper card inactivate virus while preserving DNA and RNA in the fibre matrix of the card. Because the cards inactivate the virus, the cards may be shipped without the packaging and documentation required for an infectious substance. The nucleic acids extracted from the card can be utilized as a template for RT-PCR. Virus culture lysates or purified RNA from clinical specimens or from cell culture may be applied to the cards. The protocol for preparation of these samples is available in Annex 5.3; the protocol for RNA extraction is provided in Annex 5.4.