Clinical specimens from suspected cases of measles and rubella for virologic surveillance may be submitted to any network laboratory. The specimens should be kept cold after the package is opened and throughout the accessioning process. Upon arrival, the specimens should be processed promptly and then stored appropriately according to the type of virologic specimen (refer to Chapter 3. Clinical specimens for the laboratory diagnosis and molecular epidemiology of measles, rubella, and CRS).
Laboratories that do not conduct virus isolation or molecular testing should forward the original clinical specimen in accordance with the recommended method of transport to the appropriate network laboratory to perform the necessary testing.
Laboratories with the facilities and trained staff to perform virus isolation should attempt to provide a representative virus isolate from outbreaks, or from each chain of transmission in elimination settings. If real-time RT-PCR is conducted in the receiving laboratory, an aliquot of the original clinical material is normally retained for an attempt to isolate virus. Under some circumstances, such as outbreaks that continue over several months or if cases are detected outside of the original population affected in the outbreak, collection of additional clinical specimens for genotyping and virus isolation may be required for molecular surveillance purposes (refer to Chapter 7. Molecular epidemiology of measles and rubella).
The procedures and facilities for virus isolation are included in reviews of laboratories in the GMRLN (WHO accreditation). Laboratories in the GMRLN should either maintain frozen stocks of representative virus strains that have been successfully grown in cell culture or, if facilities are not available for long-term storage at -70°C, an aliquot of the frozen virus stock should be shipped to one of the strain banks or to the appropriate RRL. The two strain banks are located at the CDC in Atlanta and the PHE in London. When sequences are submitted to the MeaNS and RubeNS databases, the submitter should indicate whether a virus isolate corresponding to the submitted sequence is available. This ‘virtual’ virus strain bank has become the most efficient way for the network laboratories to assure that virus isolates from a range of strains are available for studies, assay development and for external quality assessment.