Influenza type B

Test code: S0239 - Ultrasensitive qualitative detection of influenza B virus by reverse transcription coupled real time polymerase chain reaction. This assay does not detect influenza types A, C or D.

There are four types of influenza viruses: A, B, C and D. All influenza viruses are RNA viruses. Human influenza A and B viruses cause seasonal epidemics of disease. Influenza A viruses are the only influenza viruses known to cause flu pandemics, i.e., global epidemics of flu disease. Influenza A viruses have a very broad host range; they are also known to infect birds, pigs, horses, dogs and non-human primates.

Influenza B virus is only known to infect humans, seals and ferrets. Influenza B mutates at a rate two to three times slower than type A and consequently influenza B is less genetically diverse. Due to this lack of antigenic diversity, immunity to influenza B virus is usually acquired at an early age, though such immunity typically does not last a lifetime. Pandemics of influenza B infection are unlikely due to influenza B’s lower rate of antigenic change and its limited host range.

Influenza type C infections generally cause mild illness and are not thought to cause human flu epidemics. Influenza D viruses primarily affect cattle and are not known to infect or cause illness in people.

Influenza B virus is the only species in the genus Betainfluenzavirus of the family Orthomyxoviridae. The Influenza B viral genome consists of eight segments of linear negative-sense single-stranded RNA. Each RNA segment is enclosed in separate nucleocapsid, and the nucleocapsids are surrounded by one envelope. Influenza B viruses are not divided into subtypes but there are two recognized lineages of influenza B, B/Yamagata and B/Victoria.

Viral culture to detect influenza B virus is slow and not very sensitive. Antigen detection method is rapid but is not very sensitive. The current method of choice for detection of influenza B virus is molecular detection by polymerase chain reaction, which is highly sensitive and specific (Azar and Landry, 2018).

Utilities:

• Help confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of influenza B
• Help ensure that animal groups are free of influenza B
• Early prevention of spread of this virus
• Minimize personnel exposure to this virus

Specimen requirements:

Preferred sample - nasopharyngeal swab.

Less preferred sample - 0.2 ml whole blood in EDTA (purple top) tube.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions. For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative reverse transcription coupled real time PCR

Normal range: Nondetected