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Sankara Nethralaya
Sankara Nethralaya
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SEROLOGY

Molecular Microbiology Tests Based On PCR Offered At ABSN Kolkota Molecular Microbiology Laboratory

Polymerase Chain Reaction Tests (PCR)
 
ELISA TEST FOR EPSTEIN BARR VIRUS (EBV) IgG AND IgM
Epstein Barr Virus (EBV) is the causative agent of infectious mononucleosis and chronic active EBV infection.
EBV is associated with two human cancers – Burkitt’s lymphoma and nasopharyngeal carcinoma.
Primary infection in children is generally sub clinical and leads to a life-long carrier state.
It is a significant problem in immunocompromised patients
Application of ELISA test for the diagnosis of EBV infection
ELISA is considered the most sensitive method of diagnosis of infectious mononucleosis.
Viral Capsid Antigen (VCA) is the primary marker used for diagnosis of EBV infection.
IgG antibodies to VCA are formed 4-7 days after symptoms become evident and usually persist for life As a result, detection of IgG can indicate acute, convalescent or past phase of EBV infection. IgM can be present from 2-4 months and may persist in less than 10% cases for 6-8 months.
Interpretation of Results
Presence of VCA-specific IgG antibodies indicates immunity to infectious mononucleosis and their absence denotes susceptibility.
Presence of VCA- specific IgM antibodies indicates a recent infection by EBV.
Time of Reporting
Report will be available on the same day evening if clinical specimen is received before 12 noon. If clinical specimen is received after 12 noon, reports will be available on the next day evening.
Hepatitis B virus (HBV):
Hepatitis B surface antigen detection (HBsAg)

The antigenic determinant of the HBsAg protein moiety is antigenically heterogenous and it determines specific HBV serotypes and provides a basis for immunodetection. The principal determinant is “a” which is common to all HBV serotypes. In addition, two pairs of subspecific determinants have been identified, d/y & w/r, which are apparently mutually exclusive. Four antigenic combinations are therefore possible: adw, adr, ayw and ayr. Detection of HBsAg indicates active infection.

Time of Reporting

Report will be available on the same day evening if clinical specimen is received before 12 noon. If clinical specimen is received after 12noon, reports will be available on the next day evening.

Anti-HCV
The prevalence of HCV infection is highest among intravenous drug abusers.
ELISA for the detection of antibodies to HCV in the human serum or plasma is a qualitative in vitro diagnostic test for the detection of antibodies to HCV.
It is intended as a screening test to detect antibodies to HCV and in the differential diagnosis of Hepatitis.
Time of Reporting
Report will be available on the same day evening if clinical specimen is received before 12 noon. If clinical specimen is received after 12noon, reports will be available on the next day evening.
ELISA FOR TORCHES:

TORCHES or the TORCHES infections is a medical acronym for a set of perinatal infections (i.e. infections that are passed from a pregnant woman to her fetus). The TORCHES infections can lead to severe fetal anomalies or even fetal loss. They are a group of viral, bacterial, and protozoan infections that gain access to the fetal bloodstream transplacentally via the chorionic villi. Hematogenous transmission may occur at any time during gestation or occasionally at the time of delivery via maternal-to-fetal transfusion.

The TORCHES complex was originally considered to consist of four conditions, with the "TO" referring to "Toxoplasma". and the acronym is spelled out as follows:
TO – Toxoplasmosis / Toxoplasma gondii
R – Rubella
C – Cytomegalovirus
HE – Herpes simplex virus
S – Syphilis
The acronym has also been listed as TORCHES, for Toxoplasmosis, Rubella, Cytomegalovirus, Herpes simplex, Syphilis.The diseases present similarly, involving the heart, skin, eye, and CNS. These microbial agentes are capable cause chorioretinitis, microcephaly, and focal cerebral calcification.

Laboratory diagnosis

When physical examination of the newborn shows signs of the TORCH syndrome, the examiner may test blood, urine, and spinal fluid for evidence of the infections listed above. Diagnosis can be confirmed by culture of one of the specific pathogens or by increased levels of IgM against the pathogen. Specific ELISAs (EUROIMMUN) are developed and applied on clinical specimens (peripheral blood) to detect the presence of IgM and IgG antibodies specific to each of the agent in the TORCH panel. For detection of syphilis, commercial kits - Rapid plasma regain test and Treponema pallidum haemagglutination are used. The detection of specific antibodies to TORCH is qualitative (indicates whether IgM antibodies are present or absent) whereas the detection of IgG antibodies is quantitative (the tire of the antibodies can be determined).

The presence of IgM antibodies are suggestive of a recent or current infection whereas IgG antibodies are suggestive of previous exposure to the infectious agent.