VIROLOGY SECTION
Virology section is a specific
section where it focuses on diagnosis of HIV and Hepatitis. The screening test
for HIV, Hepatitis B and Hepatitis C were done automatically using a machine
called AxSYM.
IAxSYM
- AxSYM is a machine that been used in virology section for the purpose of screening of Hepatitis and HIV. AxSYM may also been used to measure various hormone and tumor marker in body.
- AxSYM use 2 assay which are MEIA(Micro Enzyme Imunoassay) and FPIA (Fluorescent Polarization Imunoassay)
MEIA (Micro Enzyme Immunoassay)
There are two type of reaction
for MEIA assay:
- First type-Sample, microparticle and conjugate will be bond together in incubation chamber the reaction vessel
- Second type-Sample and microparticle will be bond together in incubation chamber in reaction vessel and conjugation process occur in cell matrix
Reaction that occur in MEIA is as follows
Analite connected to microparticle
Microparticle
and sample are bound together and incubated at reaction temperature. While
incubated, analite will bound to microparticle forming an immune complex.
Immune complex bound to fiber glass matrix.
Processing probe
will isolate supernatant from incubation chamber in the reaction vessel and
dispens to matrix cell. Immune complex will bound irreversibly to fiberglass
matrix. Matrix cell washer will remove the unbound particle. Imune complex will
be trapped in the fiberglass while the supernatant will flow out through a big
hole in the matrix.
Conjugation.
Processing
probe transfer labeled alkaline phosphatase from the reagent chamber to
reaction vessel to the matrix cell. Conjugate then will bound to immune complex
to complete the antibody-analite conjugate sandwich. Matrix will be wash one
more time
MUP to MU
Bulk 1 dispencer solution added
4-Methylumbelliferyl Phosphate (MUP) to the matrix cell. Alanine phosphatase
conjugale catalyzed hydrolysis MUP to 4-Methyumbelliferone (MU).
Rate of MU generation is proportional to analite concentration
MEIA optic
measure rate of to 4-Methyumbelliferone (fluoresce particle in the fiberglass
matrix).It is proportional to the analite concentration in the test sample.
FPIA (Fluorescent Polarization Imunoassay)
FPIA uses 2 technologies to determine analite concentration;
Competative protein binding
- Need two analite system or antigen which are sample analite and labeled reagent assay analite. Sample analyte will compete competitively with labeled analite for the antibody receptor site. Each analyte system will bind with receptor site according to its relative concentration.
- If the sample analyte concentration is high, more specimen analite will bind with antibody and leave labeled analyte unbound
- If sample analyte concentration is low, less sample analyte will bind to antibody leave more labeled analyte bounded to the antibody
Fluorescent Polarization
- Polarized lamp is used to produce polarized fluorescent from labeled analyte. Mean polarization from fluorescent is proportional to molecule spinning speed.
- Molecule spinning rate in liquid is proportional to the molecule size. Smaller analyte will not spin with higher speed as compare to analyte-antibody complex with bigger size.
- AxSYM measure the different fluorescent polarization when analite-antibody complex formed.
Reaction occurs in FPIA;
Sample,
pretreatment and blank diluent will bind and incubate at reaction temperature.
Reading taken by FPIA as blank assay
Competitive
binding occur
- Antibody, label, line diluent and much more sample added to the reaction solution and incubated. Sample analite will compete with labeled analite for antibody receptor site. If the sample analyte concentration is high, more specimen analite will bind with antibody and leave labeled analyte unbound and if sample analyte concentration is low, less sample analyte will bind to antibody leave more labeled analyte bounded to the antibody
Changes is polar fluorescent
gives indication of analite concentration
- FPIA optic will scan and measure changes in fluorescent polar which is proportionally related with analite concentration in sample.
- If sample have high analite concentration, free labeled analit not bound. When stimulated with vertical polarized lamp, small fluorescent particle will spin vigorously and produce light from many corner and cause decrease in polarization. If sample have less analite concentration, labeled analit will bind with antibody, causing less free labeled analit. This labeled analite-antibody complex will spin slower. The low energy to spin allow light to pass through the complex in one direction and cause increase in polarization.
Test Been Run In AxSYM Analyzer In Microbiology Unit.(Hepatitis And HIV)
Algorithm For Hep B Virus (HBsAg) Testing And Reporting
Hepatitis B Have 3 Antigenic Structure
- Surface antigen (HbsAg)
- Core antigen (HbcAg)
- E antigen (HbeAg)
Hepatitis B Surface Antigen (HbsAg)
- HbsAg is found on the surface of Dane particle. This antigen consists of lipoprotein and carbohydrate, make it stable to heat.
- HbsAg is found in serum during incubation period before being detected with biochemical test. It presents during acute phase and disappear during convalescent. Patient that have HbsAg in serum for time more than 6 month will be classified as carrier.It is the earliest acute Hepatitis B marker and can be detected as early as 2 week after exposure. It is also a marker foe chronic and carrier condition.
- There are 4 subtype; adw, adr, ayr and ayw.
Anti HBs
- Both HBsAg and anti-HBs were used for;
- Screening patient thet need vaccination
- Scanning immunity against Hepatitis B
- Patient recovery process
- Prognosis of Hepatitis B
- Anti HBs can be detected in 2 to 4 weeks after HbsAg is not detectable anymore
- This marker also detected in individual with passive immunization of Hepatitis B immunoglobulin or active with Hepatitis vaccine.
Antigen antibody teras Hepatitis B (Anti HBC)
This antibody occur in new and
recent Hepatitis B infection and in chronic carrier.
- It can be detected before patient shows an symptom and can last for ever.
- Anti HBC normally is the only Hepatitis B marker that can be detects until the presence of anti HBs. Therefore,it is important for diagnosis for detection of infection between phase of disappear of HbsAg and the presence of anti-HBs.
- This antigen occurs during virus replication occur and can only be detected in hepatocyte and not serum. Only anti-HBc can be detectable in serum during acute phase.
Algorithm For Hep C Virus (HCV) Testing And Reporting
Hepatitis C
- HCV is a bloodborne virus closely associated with blood transfusion.
- Detection of antibodies to recombinant antigen of HCV (anti-HCV) by AxSYM have established HCV as the cause of most blood-borne as well as community-acquired non-A, non-B hepatitis.
- The presence of anti –HCV indicates that an individual may have been infected with HCV, may harbor infectious HCV and may capable of transmitting HCV infectious.
Algorithm For HIV (Anti HIV) Testing And Reporting
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