Enterovirus Quantitative RT-PCR:
Why Enterovirus (Quantitative) RT-PCR Test?
CLINICAL INFORMATION
Enterovirus are positive-sense RNA viruses in the Picornaviridae family. These viruses were initially classified by serotype as polioviruses, echoviruses and coxsackie viruses (A and B). However on their further higher genomic studies, later demonstrated a significant overlap in their biological characteristics among multiple subtypes (serotypes). Therefore enteroviruses are now named with consecutive numbers (eg. EV68, EV 69 etc). So, three of the most common types of Non-Polio Enteroviruses are classified as Enterovirus D68 (EV-D68), Enterovirus A71 (EV-A71) and Coxsackie virus (CV)-A6. The usual (normal) site (route of infection is payer’s patches in the stomach) of Enterovirus replication in the gastrointestinal tract (generally, the infection remains typically subclinical), however in other proportion of cases virus is found to spread to other organs (like spleen, liver, bone marrow, skin, heart etc) causing systemic manifestations. Example, Respiratory disease like pneumonia (Upper Respiratory Tract Infections - in children is caused by Enterovirus D68 ie EV-D68), conjunctivitis, aseptic meningitis and/or encephalitis (CNS manifestations – Hence CSF sample specimen is mostly preferred), myocarditis and/or pericarditis, acute flaccid paralysis (sudden onset of weakness in one or both limbs -hands or legs), inflammatory muscle disease, hepatitis etc. In the CNS, this Enterovirus specifically affects the area of the spinal cord called Gray Matter, resulting in ‘weak muscles’ and ‘reflexes in the body. The Non-Polio Enterovirus manifestations include fever, runny nose, sneezing, cough, skin rash, sore throat, mouth blisters (Hand, foot and mouth disease), body and muscle aches etc. Quantitative and qualitative analysis: Quantitative analysis is usually performed for isolation of gross volume in the given sample specimen (eg. Detection of the width of band or a peak obtained from the sample in PAGE revealing specific protein shows the intensity or stage of the disease) helps to track the course of infection, While a qualitative analysis is usually performed in asymptomatic individuals (suspected patients). Hence before this assay patients with clinical history and clinical investigations including signs and symptoms of (eg. Enterovirus) infection must be interpreted in the context of its clinical picture, prior to this test. A positive test result confirms the infection (It is also true that a negative test result does not always necessarily rule out the possibility of an infection eg. If the patient was tested during the incubation period of infection). Qualitative analysis is performed for the assessment of purity (eg. Detection of a single band or a peak in PAGE revealing specific protein). A negative result in qualitative assay does not always rule out the possibility of an enterovirus infection (eg. If the virus in the patient was in an incubation period).PCR – Polymerase Chain Reaction (PCR) technology (involves 3 main stages, denaturation, annealing and elongation), is a very sensitive method used in medical as well as research purposes for elucidating DNA sequencing. This test involves extraction of genetic material by isolation and this technique amplifies the genetic material (DNA is amplified by Cloning using PCR) present in the sample specimen to many folds by replication. Thus this amplified sample specimen detects and reads the signal and test results are interpreted as positive or negative. Therefore PCR application in genetic testing is performed to detect pathogenic or altered or mutated DNA (i.e error in a specific part of DNA). RT-PCR: Reverse Transcriptase PCR or RT-PCR allows the use of RNA as a template (since some viruses contain only single-stranded RNA instead of DNA). An additional step allows the use of RNA as a template (RNA is transcribed using the enzyme RNA Polymerase into its complementary DNA – cDNA, which is RNA-DNA hybrid), which is then amplified, detected and quantified for test results. Hence enterovirus quantitative RT-PCR Test is performed. This assay may detect viruses from a variety of specimen types like a serum, plasma, lesion, stool, throat swab (while throat swab may also be accepted) etc, but CSF is the most preferred sample specimen of choice.
General Instructions:
Sample Requirement: Specimen – As Guided by the physician. Test Preparation: None.
NOTE - Sample for specimen collections may vary based on the patient’s condition/cases according to the patient’s presenting complaints/signs or symptoms:
SPECIMEN REQUIREMENT (Special or Rare Cases) - As instructed and guided by Physician / Clinician / Pathologist / as per Laboratory’s requirements, according to procedures and protocols.
This Multi-Specialty Clinical Referral Laboratory RTDIAGNOSTICS provides precise and accurate tests with an extensive range of testing services to the medical centres to help in the diagnosis and identification of pathology in the test specimens for infectious diseases and also to evaluate the function of organ systems of the patient. It prevents further complications and helps to stabilize and restore health to near normalcy at the earliest without delay.
