In: Nursing
Cellular/ structural (in case of viruses) characteristics. Add information here about morphology, cellular characteristics, genome (RNA or DNA in case of viruses) and gram stain characteristics, virulence factors. Explain why this information is important. Include how it relates to the information covered in class- which chap number and what was taught.
Viruses are the smallest (200-300nm in diameter), obligate intracellular infectious agents.
They do not have cellular organization.
The genome is an element of nucleic acid, either DNA or RNA.
Their genome in enclosed in a protein shell known as capsid, which may be surrounded by a lipid containing membrane called envelope.
The entire infectious unit is called "virion"-an extracellular infectious virus particle.
Two types of proteins are present in viruses , Viz
1. Structural proteins -proteins present in the coat of the virus
2. Non structural proteins- these are functional proteins such as haemagglutinins and enzymes.
These are the virulence factors of viruses.
For example,
Haemagglutinins are proteins present as spikes on the envelope which can agglutinate erythrocytes of various animal species.
Viral enzyme neuraminidase acts on receptors of erythrocytes and destroys them hence known as receptor destroying enzyme.
Viruses cannot be detected with a Gram stain.