Module

1. MODULE – TWO
NUCLEIC ACIDS IN VACCINES AND DIAGNOSIS
BIOLOGY FOR ENGINEERS

2. INTRODUCTION TO NUCLEIC ACIDS AND THEIR ROLE IN GENETIC
MATERIAL.
 Nucleic acids are vital biomolecules that play a critical role in the storage, transmission, and
expression of genetic information in all living organisms.
 Nucleic acids are fundamental to life, serving as the blueprint for all biological functions and
processes.
 The two main types of nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid
(RNA).
 Understanding their structure, function, and role in genetic material provides insights into the
molecular mechanisms that govern living organisms and opens up avenues for scientific and
medical advancements.
 Here's a detailed introduction to nucleic acids and their role in genetic material:

3. STRUCTURE OF NUCLEIC ACIDS
DNA (Deoxyribonucleic Acid)
1.Components: DNA is a polymer composed of monomers called nucleotides. Each nucleotide
consists of three components:
1. A nitrogenous base (adenine, thymine, cytosine, or guanine).
2. A five-carbon sugar called deoxyribose.
3. A phosphate group.
2.Double Helix: DNA molecules typically exist as a double helix, where two strands are wound
around each other. The strands are held together by hydrogen bonds between the complementary bases
(A-T and C-G).
3.Antiparallel Strands: The two strands run in opposite directions, with one strand oriented 5’ to 3’
and the other 3’ to 5’.

4. RNA (Ribonucleic Acid)
1.Components: RNA is also composed of nucleotides, but with slight differences:
1. The sugar is ribose instead of deoxyribose.
2. The nitrogenous bases are adenine, uracil (replacing thymine), cytosine, and guanine.
2.Single-Stranded: RNA is usually single-stranded but can form complex secondary structures through
intramolecular base pairing.

5. ROLE IN GENETIC MATERIAL
DNA's Role
1.Genetic Information Storage: DNA carries the genetic blueprint of an organism. The sequence of
nucleotides encodes instructions for the synthesis of proteins, which determine an organism's traits
and functions.
2.Replication: DNA replication is a critical process during cell division. Each strand of the DNA
double helix serves as a template for the creation of a new complementary strand, ensuring genetic
continuity.
3.Gene Expression: Specific segments of DNA, called genes, are transcribed into RNA, which is then
translated into proteins. This flow of genetic information from DNA to RNA to protein is known as
the central dogma of molecular biology.

6. RNA's Role
1.Messenger RNA (mRNA): mRNA carries the genetic information from DNA to the ribosome,
where proteins are synthesized. It acts as a template for protein synthesis.
2.Transfer RNA (tRNA): tRNA molecules bring amino acids to the ribosome during protein
synthesis. Each tRNA recognizes specific codons in the mRNA through its anticodon.
3.Ribosomal RNA (rRNA): rRNA is a key component of ribosomes, the molecular machines that
synthesize proteins. It plays a catalytic role in the formation of peptide bonds between amino acids.
4.Regulatory Roles: Various small RNAs, such as microRNAs (miRNAs) and small interfering
RNAs (siRNAs), regulate gene expression by interfering with the translation or stability of specific
mRNAs.

7. Nucleic Acids in Genetic Inheritance
•Heredity: DNA is the hereditary material that is passed from parents to offspring. During sexual reproduction,
genetic recombination creates genetic diversity, while mitosis ensures identical genetic material is passed to
daughter cells.
•Mutations: Changes in the nucleotide sequence of DNA (mutations) can lead to variations in the genetic code.
While some mutations are harmful, others can be beneficial and drive evolution by introducing new traits.
Biotechnological Applications
Nucleic acids have numerous applications in biotechnology, medicine, and research:
•Genetic Engineering: Techniques like CRISPR-Cas9 allow precise editing of DNA sequences, enabling the
modification of genes for various purposes.
•Diagnostics: Nucleic acid-based tests, such as PCR (polymerase chain reaction), are used for detecting
pathogens, genetic disorders, and cancers.
•Therapeutics: RNA-based therapies, including mRNA vaccines (like those for COVID-19), represent a rapidly
growing field in medicine.

8. NUCLEIC ACIDS IN VACCINES
 Nucleic acids play a crucial role in modern vaccine development, particularly with the advent of
DNA and RNA vaccines.
 These types of vaccines represent a significant advancement in immunology and have been pivotal in
the rapid development of vaccines against various infectious diseases, most notably COVID-19.
 DNA and RNA vaccines represent a revolutionary leap in vaccine technology, offering rapid, flexible,
and effective methods to combat infectious diseases.
 Their successful application in preventing COVID-19 highlights their potential to address current and
future global health challenges.
 Here’s a detailed explanation of how DNA and RNA vaccines work, along with their applications in
preventing infectious diseases.

9. DNA VACCINES
Mechanism:
1.Genetic Material Introduction: DNA vaccines involve the use of a small, circular piece of DNA
called a plasmid. This plasmid contains genes that encode antigens (proteins from a pathogen).
2.Cellular Uptake: Once the DNA vaccine is administered, typically via injection, the plasmid enters
the host cells. This can be facilitated by techniques such as electroporation, which uses electrical pulses
to increase cell membrane permeability.
3.Transcription and Translation: Inside the host cell nucleus, the plasmid DNA is transcribed into
messenger RNA (mRNA).
4.Protein Production: The mRNA is then translated in the cytoplasm to produce the antigen proteins.
5.Immune Response: These antigens are processed and presented on the cell surface by major
histocompatibility complex (MHC) molecules, triggering the host’s immune system. This stimulates
both humoral (antibody-mediated) and cellular (T-cell-mediated) immune responses.

10. Advantages:
•Stability: DNA is more stable than RNA, making storage and transportation easier.
•Rapid Development: DNA vaccines can be designed quickly once the genetic sequence of the
pathogen is known.
•Safety: DNA does not integrate into the host genome, minimizing the risk of insertional
mutagenesis.
Applications:
•Infectious Diseases: DNA vaccines have been explored for various infectious diseases such as HIV,
Zika, and influenza. However, none had been widely licensed for human use before the COVID-19
pandemic.

11. RNA VACCINES
Mechanism:
1.Genetic Material Introduction: RNA vaccines use synthetic mRNA that encodes the antigen
proteins of the pathogen.
2.Cellular Uptake: After injection, the mRNA enters host cells, typically aided by lipid nanoparticles
that protect the mRNA and facilitate its entry into cells.
3.Translation: The mRNA is translated by the host cell’s ribosomes into the antigen proteins.
4.Immune Response: These proteins are processed and presented on the cell surface by MHC
molecules, triggering an immune response similar to that of DNA vaccines.

12. Advantages:
•Speed and Flexibility: RNA vaccines can be designed and produced more rapidly than traditional
vaccines.
•Non-integrating: mRNA does not integrate into the host genome, reducing the risk of genetic
mutations.
•Strong Immune Response: mRNA vaccines are highly effective in eliciting strong immune
responses, including robust T-cell activation.
Applications:
•COVID-19: The most notable application has been the development of mRNA vaccines against
SARS-CoV-2, the virus responsible for COVID-19. Pfizer-BioNTech’s BNT162b2 and Moderna’s
mRNA-1273 vaccines have shown high efficacy and safety profiles.
•Other Diseases: Ongoing research is investigating mRNA vaccines for diseases such as rabies, Zika,
and certain types of cancer.

13. Applications in Preventing Infectious Diseases
The development and application of DNA and RNA vaccines have significantly impacted the approach to preventing
infectious diseases. Here are some key points:
1.Rapid Response to Emerging Pathogens: The flexibility and speed of DNA and RNA vaccine platforms enable quick
responses to emerging infectious diseases. This was demonstrated during the COVID-19 pandemic, where vaccines were
developed, tested, and distributed within a year of the virus’s emergence.
2.Customizable Design: These vaccines can be easily modified to target different strains or mutations of pathogens, which
is particularly useful for viruses like influenza and SARS-CoV-2 that mutate rapidly.
3.Global Vaccination Efforts: The scalability of nucleic acid vaccines supports large-scale manufacturing, essential for
global vaccination campaigns. This is crucial in pandemic situations where rapid mass immunization is needed.
4.Broader Applications: Beyond infectious diseases, DNA and RNA vaccines hold potential for cancer immunotherapy,
where they can be designed to target tumor-specific antigens, as well as for personalized medicine approaches.
5.Research and Development: The success of mRNA vaccines in COVID-19 has spurred significant investment and
research into nucleic acid vaccines, promising future advancements in vaccine technology and broader applications in
medicine.

14. NUCLEIC ACIDS IN DIAGNOSIS
Overview of Nucleic Acid-Based Diagnostic Techniques
 Nucleic acid-based diagnostic techniques have revolutionized the field of disease detection by
providing highly specific, sensitive, and rapid means of identifying pathogens and genetic
mutations.
 Among these techniques, Polymerase Chain Reaction (PCR) stands out as a cornerstone
technology.
 Below is an overview of PCR and other key nucleic acid-based diagnostic methods.

15. POLYMERASE CHAIN REACTION (PCR)
Principle and Process: PCR is a technique used to amplify small segments of DNA or RNA, allowing
for the detection and analysis of genetic material. The process involves repeated cycles of:
1.Denaturation: Heating the sample to separate the DNA strands.
2.Annealing: Cooling the sample to allow primers to bind to the target DNA sequence.
3.Extension: Raising the temperature for DNA polymerase to synthesize the new DNA strand by
adding nucleotides.
These steps are repeated multiple times (typically 25-35 cycles), leading to exponential amplification
of the target DNA

16. Applications in Diagnostics:
PCR is widely used for detecting pathogens, genetic mutations, and variations associated with
diseases. Its applications include:
•Infectious Diseases: Identifying bacterial, viral, and fungal pathogens (e.g., HIV, SARS-CoV-2,
Mycobacterium tuberculosis).
•Genetic Disorders: Detecting mutations and genetic markers linked to conditions like cystic fibrosis
and sickle cell anemia.
•Cancer: Identifying specific gene mutations and translocations associated with different cancers.

17. Advantages:
1. Sensitivity: Capable of detecting minute amounts of DNA/RNA.
2. Specificity: High precision in targeting specific genetic sequences.
3. Speed: Rapid results, often within a few hours.
Limitations:
 Contamination Risk: High sensitivity makes it prone to contamination, leading to false positives.
 Technical Expertise: Requires specialized equipment and trained personnel.

18. Other Nucleic Acid-Based Diagnostic Techniques
1. Real-Time PCR (qPCR): An advanced form of PCR that allows for quantitative measurement of
DNA or RNA. It uses fluorescent markers to monitor the amplification process in real-time, providing
both qualitative and quantitative data.
Applications:
•Quantification of viral load in infections (e.g., HIV, hepatitis).
•Monitoring gene expression levels.
•Detection of genetically modified organisms (GMOs).
2. Reverse Transcription PCR (RT-PCR): Combines reverse transcription of RNA into DNA (cDNA)
with PCR amplification. It is particularly useful for detecting RNA viruses and studying gene expression.
Applications:
•Diagnosis of RNA viruses (e.g., influenza, SARS-CoV-2).
•Analysis of gene expression in research and clinical settings.

19. 3. Digital PCR (dPCR):
•A highly precise method that partitions the sample into thousands of droplets or wells, performing
PCR in each. It provides absolute quantification of target DNA/RNA without the need for standard
curves.
Applications:
•Rare mutation detection.
•Liquid biopsy for cancer monitoring.
•Precise quantification of viral load.

20. 4. Nucleic Acid Hybridization Techniques:
a. Fluorescence In Situ Hybridization (FISH): Uses fluorescent probes that bind to specific
DNA/RNA sequences in cells, allowing for visualization under a microscope. It is used for detecting
genetic abnormalities and chromosomal aberrations.
Applications:
•Diagnosis of genetic disorders (e.g., Down syndrome).
•Identification of chromosomal translocations in cancers.
b. Microarray Analysis: Involves hybridizing cDNA or RNA to a grid of DNA probes on a microarray
chip. It allows for the simultaneous analysis of thousands of genes.
Applications:
•Gene expression profiling.
•Comparative genomic hybridization for detecting copy number variations.

21. 5. Next-Generation Sequencing (NGS): High-throughput sequencing technology that allows for
comprehensive analysis of entire genomes or specific genomic regions. It provides detailed information
about genetic variations, mutations, and gene expression.
Applications:
•Whole-genome sequencing for rare genetic diseases.
•Targeted sequencing for cancer mutation panels.
•Metagenomics for identifying microbial communities in clinical samples.
Nucleic acid-based diagnostic techniques, particularly PCR and its variants, have become indispensable
tools in modern diagnostics. They offer unparalleled sensitivity, specificity, and speed in detecting a
wide range of pathogens and genetic abnormalities. As technology advances, these methods continue to
evolve, providing even more powerful tools for disease detection and management.

22. THANK YOU