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35 Differences Between PCR and ELISA Assays in Laboratory Testing

35 Differences Between PCR and ELISA Assays in Laboratory Testing
01 Dec

Enzyme-Linked Immunosorbent Assay (ELISA) and Polymerase Chain Reaction (PCR) are two crucial methods used in laboratory testing for various objectives. 

A laboratory method used in molecular biology, PCR stands for Polymerase Chain Reaction and is used to amplify and analyze DNA (deoxyribonucleic acid). A potent and popular technique for identifying, measuring, and analyzing certain DNA sequences is PCR. Kary Mullis, who received the 1993 Nobel Prize in Chemistry for developing the process initially, did so in the 1980s.

The versatility and accuracy of PCR have made it a vital instrument in molecular biology, significantly advancing scientific fields such as genetics, medicine, and other fields.

Enzyme-Linked Immunosorbent Assay is referred to as ELISA. It is a popular laboratory method for identifying and measuring chemicals in biological samples, including proteins, antibodies, hormones, and other compounds. Medical diagnostics, research, and quality control procedures frequently use ELISA.

Using certain antibodies that have the ability to attach to the target molecule of interest is the fundamental idea behind ELISA. 

There are various ELISA variants, including sandwich, direct, indirect, and competitive ELISA, each with specialized uses based on the kind of molecule being found and the objectives of the experiment. Clinical laboratories employ ELISA extensively for disease diagnosis, treatment response monitoring, and a variety of research applications in immunology, microbiology, and biochemistry.

S.No.

Aspects

PCR

ELISA

1

Full Name

Polymerase Chain Reaction

Enzyme-Linked Immunosorbent Assay

2

Type of Assay

Nucleic Acid Amplification

Protein Detection

3

Purpose

Detecting DNA/RNA

Detecting Proteins

4

Sensitivity

High sensitivity

Moderate sensitivity

5

Specificity

High specificity

Moderate specificity

6

Sample Type

DNA/RNA samples

Serum, plasma, or other biological fluids

7

Detection Target

Genetic sequences

Antigens or antibodies

8

Amplification Step

Yes

No

9

Enzymes Used

DNA polymerase

Enzymes (e.g., horseradish peroxidase)

10

Endpoint Detection

Real-time monitoring or gel electrophoresis

Colorimetric or fluorescent signals

11

Quantification

Quantitative and qualitative results

Quantitative or qualitative results

12

Time Required

Several hours to a few days

Hours

13

Cost

Expensive

Relatively Inexpensive

14

Automation

Semi-automated to fully automated systems

Typically manual or semi-automated

15

Multiplexing

Possible with multiplex PCR

Limited multiplexing capabilities

16

Analyte Concentration

Low concentrations of nucleic acids

Higher concentrations of antigens/antibodies

17

Detection Method

Fluorescence or gel electrophoresis

Colorimetric or chemiluminescence

18

Clinical Applications

Diagnosing infectious diseases, genetic disorders

Detecting antibodies, antigen presence

19

Sensitivity to Contaminants

Susceptible to contamination

Less susceptible to contamination

20

Sample Storage

Requires cold storage for stability

Samples can be stored at room temperature

21

False Positives

Less common

More common

22

False Negatives

Less common

Less common

23

Throughput

Lower throughput

Higher throughput

24

Test Timeframe

Longer turnaround time

Faster results

25

Sensitivity to Inhibitors

Sensitive to PCR inhibitors

Less sensitive to inhibitors

26

Clinical Validation

Often requires confirmatory tests

May not require confirmatory tests

27

Target Molecule Stability

DNA/RNA can be stable for a long time

Proteins may degrade over time

28

Detection Mechanism

Amplification of target sequences

Antigen-antibody interactions

29

Amplification Cycles

Multiple amplification cycles are required

No amplification cycles

30

Equipment

PCR machine or thermocycler

ELISA plate reader and washer

31

Skill Level Required

Requires skilled technicians

Less technical expertise required

32

Sample Volume

Small sample volumes required

Larger sample volumes required

33

Variability in Results

Less variability

More variability

34

Quantitative Range

Wide quantitative range

Limited quantitative range

35

Historical Use

Common in molecular biology and genetics

Common in immunology and serology

 

Frequently Asked Questions (FAQ’S)

Q1. What makes RT-PCR different from PCR?

While RT-PCR (Reverse Transcription Polymerase Chain Reaction) is used to amplify RNA, PCR (Polymerase Chain Reaction) is used to amplify DNA. Reverse transcription is a step in RT-PCR that turns RNA into complementary DNA (cDNA).

Q2. What function do primers serve in PCR?

During PCR, primers are brief DNA sequences that attach to the target DNA area and act as the beginning sites for DNA polymerase to synthesize new DNA.

Q3. How does PCR function?

The three primary processes of PCR are extension, annealing, and denaturation. The process of making a copy of the original DNA involves heating DNA to separate its strands, primers binding to the target sequence, and DNA polymerase extending the new strand.

Q4. Which ELISA kinds are there?

ELISA comes in a variety of forms, such as competitive, sandwich, direct, and indirect. According to the target molecule and the required assay sensitivity, each kind has particular applications.

Q5. What benefit does ELISA offer in terms of diagnostics?

ELISA has the ability to analyze many samples at once and is very specific and sensitive. It is extensively employed in clinical diagnostics to identify different biomarkers, autoimmune conditions, and infectious infections.

Q6. Is ELISA automatable?

Indeed, automation of ELISA can improve its performance and lower assay variability. High-throughput laboratories frequently use automated ELISA systems.
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