Biotechnology Applications (Diagnostics, Therapy, Vaccines)

Biotechnology applications

Use of biological systems for diagnostic, therapeutic, and preventive purposes

Diagnostic applications

ELISA, DNA diagnostic systems, DNA fingerprinting

Therapeutic applications

Antibodies and gene therapy

Prevention

Vaccines

Molecular diagnostics

Methods to detect pathogens using DNA or immunological techniques

Traditional diagnostics

Growth in culture, slow and costly

Modern diagnostics

Specific, sensitive, and simple

Antigen

A molecule recognized by antibodies (usually from a pathogen)

Antibody

A protein that binds specifically to an antigen

ELISA (Enzyme-Linked Immunosorbent Assay)

Detects antigen-antibody interactions using enzyme-linked color change

ELISA step 1

Bind sample to microtiter plate

ELISA step 2

Add primary antibody (binds antigen)

ELISA step 3

Add secondary antibody with enzyme

ELISA step 4

Add substrate → color change

DNA diagnostic systems

Use nucleotide sequences to detect pathogens

Nucleic acid hybridization

Binding of complementary DNA strands

DNA probe

Labeled DNA used to detect complementary sequences

Limitation of radioactive probes

Short-lived, hazardous, requires special handling

Chemiluminescent detection

Nonradioactive method for detecting DNA

DNA fingerprinting

Unique genetic profile of an individual

VNTRs

Variable number tandem repeats in DNA

STRs

Short tandem repeats used in PCR-based fingerprinting

RFLP

Restriction fragment length polymorphism using restriction enzymes

PCR fingerprinting

Amplifies STR regions for analysis

DNA fingerprinting steps

Extract DNA, cut/amplify, separate by gel, visualize bands

Applications of DNA fingerprinting

Paternity testing, forensics, disease diagnosis

CODIS

FBI database using STR markers for DNA identification

Antibodies (therapeutic)

Used to target disease-related molecules

Polyclonal antibodies

Mixture of antibodies targeting multiple antigen sites

Monoclonal antibodies

Antibodies targeting a single antigen site (used therapeutically)

Gene therapy

Delivery of genes to treat disease

Ex vivo gene therapy

Modify cells outside body then return to patient

In vivo gene therapy

Deliver genes directly into body

Gene delivery vectors

Viruses, liposomes, DNA guns

Vaccines

Stimulate immune system using pathogen components

Immune response to vaccines

Produces antibodies and memory B cells

Subunit vaccines

Use part of pathogen

Attenuated vaccines

Weakened live pathogen

Inactivated vaccines

Dead pathogen

DNA/RNA vaccines

Genetic material used to produce antigen (e.g., COVID-19 vaccines)