general introduction

1. Cauliflower Mosaic Virus
NK.SUJEETH
I-M.Sc. INDUSTRIAL BIOTECHNOLOGY
DEPARTMENT OF MICROBIAL BIOTECHNOLOGY

2. INTRODUCTION
 Genus – caulimovirus
 Family – caulimoviridae
 Grouped - hepadnavirus into pararetrovirus
 Infects – brassicaceae , solanaceae , datura &nicotiana
 Symptoms – mosaic , reduced growth , necrotic lesions
 Depends – viral strain , environmental conditions

3. STRUCTUR
E1) Icasohedron with diameter of 52nm built from 420 capsid protein
subunits arranged in triangular form , which surrounds solvent filled
central cavity.
2) Circular double stranded DNA of 80kb.
3) Nicks form from met t-RNA & two RNA primers for reverse
transcriptase.
4) Single stranded nicks in viral DNA are repaired forming supercoiled
molecule that binds to histones .
5) DNA is transcribed into full length 35s RNA and sub-genomic 19s
RNA.

4. GENOME
CaMV Open Reading Frames(ORF)
 ORF I – movement protein
 ORF II – insect transmission factor
 ORF III – structural protein & DNA binding
 ORF IV – capsid protein
 ORF V – protease , Reverse Transcriptase & Rnase H
 ORF VI – translation activator , inclusion body formation
/trafficking , possibly more function
 ORF VII – unknown function

5. REPLICATION

6. REPLICATION - PROCESS
1 - Viral protein encapsidated ( β γ ).
2 – Viral DNA enters nucleas , with host histones forms minichromosome.
3 – Host DNA dependent RNA polymerase transcribes the 35s RNA promoter and transcription
19s RNA.
4 – viral RNAs pass into host cytoplasm.
5 - 3‛ end of t-RNA anneals near 5’ end of 35s RNA.
6 – t-RNA primer synthesis by viral Reverse Transcriptase of new strand.
7 – RNase H remove RNA from DNA-RNA complex.
8 – New DNA binds 35s promoter at 3’end of RNA , -strand synthesis continues,.
9 - -strand synthesis completes , RNase H exposes primers ,forming γ-strand.
10 – RNase H exposes forming β-DNA.( -strand reaches 5’end of new β-strand then β-strand reaches
5’end of the γ-strand and then γ-strand reaches the 5’end of -strand)

7. CAULIFLOWER MOSAIC VIRUS AS VECTOR
1) Capacity for insertion of foreign gene .
2) But , above few hundred nucleotides , it has ineffective
capacity.
3) Helper virus cannot used & foreign DNA expelled , wild type
virus are produced.

8. REFERENCE
BOOK REFERENCE :
BIOTECHNOLOGY BY U.SATHYANARAYANA.
Section VII – Plant/Agricultural Biotechnology
Chapter 49: Genetic engineering of plants
Page no :580 to 582
ONLINE REFERENCE :
https://en.m.Wikipedia.org>wiki>cauliflower mosaic virus

9. THE END