This document discusses viral vectors, which are tools used by molecular biologists to deliver genetic material into cells. It describes how viruses are efficient at transferring their DNA into host cells and can be modified to insert exogenous genes. The document outlines some key properties of viral vectors like safety through deletion of viral replication genes. It then describes some common viral vectors, including adenovirus, adeno-associated virus, herpes virus, lentivirus, and retrovirus. Finally, it discusses some applications of viral vectors like gene therapy and using viruses expressing pathogen proteins as vaccines.

1. VIRAL VECTOR
Presented by;
Manka Mary
1st M.Sc.Microbiology

2. INTRODUCTION
 Vector is a vehicle used to transfer the genetic
material into a target cell.

3.  Viral vectors are tools used by molecular biologist to
deliver genetic material into cells.

4. Uses of viral vectors
 Virus are obligate intracellular parasites.
 Very efficient at transferring viral DNA into host
cells.
 Specific target cells depending on the viral
attachment proteins’
 Gene replacement non essential genes of virus are
deleted and exogenous genes are inserted.

5. Properties of Viral Vectors
Safety:
 Deletion of the viral genome critical for viral
replication e.g helper virus.
Low Toxicity.
Stability:
 Some viruses are genetically unstable and can rapidly
rearrange their genomes.
Identification;
 Viral vectors are often give certain genes that helps
identify which cells took up the viral gene e.g
antibiotic resistance genes

6. Types of Viral Vectors
DNA Viral Vectors;
Adenovirus
Adeno-Associated virus
Herpes virus
RNA Viral Virus;
 Lentivirus
 Retrovirus

7. Adenovirus
 It causes common cold.
 It is the double stranded DNA.
 It is the naked virus and it has interactions proteins which to penetrate into
host cell.

8. Adeno-Associated virus
 It is a small virus which infects humans.
 The virus causes a very mild immune response,
lending further support to its apparent lack of
pathogenicity.

9. Herpes virus
 This type of viral vector has the ability to deliver large-scale
quantities of exogenous DNA.
 The main role is maintenance of transgene expression.

10. Lentivirus
 Lentiviruses are a type of retrovirus that are able to integrate into non-
dividing cells and do not require mitotic cell division in order to function.
 Instead, the genome enters the cell DNA via reverse transcription and is
incorporated in a random position of the cell genome.

11. Retrovirus
 Retrovirus vectors are commonly used and known to integrate into the
genome of the infected cell in a stable and permanent fashion.
 Reverse transcriptase in the virus allows integration into the host genome.

12. Applications
Gene Therapy:
 Gene therapy is a technique for correcting defective
genes responsible for disease development.
 There are following delivery system for gene therapy:
Physical methods
Non-viral vectors
Viral vectors

14. In vaccination
 Viruses expressing pathogen proteins are currently
being developed as vaccines against these pathogens,
based on the same rationale as DNA vaccines.
 A viral vaccine induces expression of pathogen
proteins within host cells. Since viral vaccines
contain only a small fraction of pathogen genes, they
are much safer and sporadic infection by the pathogen
is impossible.
 Adenoviruses are being actively developed as
vaccines.

16. Thank You