4.  Host Range: The specific types of cells a virus can infect in its host species represent the host range of the virus.

• •  Animal virus

•  Plant virus

•  Bacterial virus (bacteriophage)

Host range is determined by attachment sites (receptors)  

Important points to remember:

• •  VIRION – a complete single viral particle

•  Obligatory intracellular parasites

•  Contain DNA or RNA

•  Do not undergo binary fission

•  Sensitive to interferon

•  Contain a protein coat

•  Some are enclosed by an envelope

•  Some viruses have spikes

•  Most viruses infect only specific types of cells in one host

•  Host range is determined by specific host attachment sites and cellular factors (receptors)

•  Viruses replicate through replication of their nucleic acid and synthesis of the viral protein.

•  Viruses do not multiply in chemically defined media

•  All ss-RNA viruses with negative polarity have the enzyme transcriptase (RNA dependent RNA polymerase) inside virions.

•  Retroviruses and hepatitis B virus contain the enzyme reverse transcriptase.  

 

REFERENCES:

Text Books:

1. Jeffery C. Pommerville. Alcamo's Fundamentals of Microbiology (Tenth Edition). Jones and Bartlett Student edition.

2. Gerard J. Tortora, Berdell R. Funke, Christine L. Case. Pearson - Microbiology: An Introduction. Benjamin Cummings.

Reference Books:

1. Lansing M. Prescott, John P. Harley and Donald A. Klein. Microbiology. Mc Graw Hill companies.

2. Biology, Raven and Jhonson, 6 th edition (2001)

3. Microbiology, Pelczar. M.J , Chan E.C.S, Kreig N.R, 5th edition (2007)