Detection of Rubella RNA by RT–PCR or Virus Isolation
Detection of rubella RNA in a clinical sample can provide laboratory confirmation of infection. Quantitative real–time RT–PCR (RT–qPCR) and endpoint RT–PCR to detect rubella RNA are performed at CDC. These protocols are available to qualified laboratories (email: firstname.lastname@example.org).
The RT–qPCR, which is more sensitive than endpoint RT–PCR, is used for detection of rubella RNA, while endpoint assays are used to amplify the region of the rubella genome required to determine genotype. For more information, see Genetic Analysis page.
Rubella virus isolation will be performed at the discretion of the CDC rubella lab. For more information, email email@example.com.
Specimens for RNA Detection
Pharyngeal samples, including throat swabs, nasal swabs, or nasal aspirates, are the preferred specimens for detecting rubella RNA in both CRS cases and suspected acute cases. Urine samples may also contain rubella virus. Collection of both pharyngeal and urine samples, when feasible, can increase the likelihood of detecting the virus.
The timing of specimen collection is important. Ideally, for acute rubella cases, viral specimens should be collected as soon after symptom onset as possible, preferably one to three days after onset, but no later than seven days post-onset.
CRS cases can continue to shed virus for up to one year after birth. However, samples should be collected prior to 3 months of age if possible because by 3 months of age approximately 50% will no longer shed virus. Infants with CRS should be considered infectious until they are at least 1 year old or until two cultures of clinical specimens obtained one month apart after the infant is older than 3 months of age are negative for rubella virus. CDC may use rubella virus RNA detection as a surrogate for detection of rubella virus by culture at the discretion of the CDC rubella lab.
For more details about specimens for RNA detection, see Specimen Collection, Storage, & Shipment.