• SIZE - MEASURED IN NANOMETERS

• SUB-LIGHT MICROSCOPIC

• 4 MAJOR GROUPS

1. ANIMAL

2. PLANT

3. BACTERIAL

4. VIRUSES OF EUCARYOTIC MICROBES• FUNGI AND PROTISTA

• COMMON CHARACTERISTICS OF VIRUSES

• ALL ARE OBLIGATE INTRACELLULAR PARASITES

• ALL HAVE NO INDEPENDENT METABOLIC PATHWAYS FOR ENERGY SYNTHESIS

• THEY ALL POSSESS ONLY ONE NUCLEIC ACID - RNA OR DNA NEVER BOTH

• THEY ALL HAVE A COMMON BASIC STRUCTURE SEEN IN 1942 WITH EM

• VARIABILITY OF VIRUSES– TYPE OF NUCLEIC ACID

• CIRCULAR, LINEAR, DS, SS, IN SEGMENTS

– MORPHOLOGY OF CAPSID

• N SPIKES – NEURAMINIDASE • H SPIKES – HEMAGGLUTININ • H1N1 – 1918 – FLU VIRUS

– Killed 40 – 50 million people world wide• H5NI – TODAYS BIRD FLU• Indonesia - killed 7 people• Swine flu virus

• IS THERE EVER ANYTHING ELSE IN THE CORE IN ADDITION TO THE NUCLEIC

ACID?• INTRACELLULAR REPLICATION

• CLASSIFICATION OF VIRUSES - INTERNATIONAL COMMITTEE ON TAXONOMY OF VIRUSES (ICTV) - 1966

• TAXONOMIC LEVELS• ORDER, FAMILY,GENUS,SPECIES• NUCLEIC ACID• MORPHOLOGY• PRESENCE OR ABSENCE OF AN ENVELOPE• STRATEGY OF REPLICATION