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​🔬 Microbiology: Fungi and Viruses, ​General Features of Viruses, ​I.…
​🔬 Microbiology: Fungi and Viruses
​General Features of Viruses
Obligate Intracellular Parasites: Depend on host cell's biochemical machinery for replication.
Size: Small (20 nm – 300 nm); they pass through bacterial filters.
Genetic Material: Only DNA or RNA molecules.
Reproduction: Occurs by assembly of individual components, not by binary fission.
Lack Capacity: Unable to produce energy or make their own protein/replicate.
​I. Fungi - Morphological Classification
1. Filamentous (Molds)
Shape: Long branching. / Structure: Consists of hyphae, forming a mass called Mycelium. /
Reproduction: Reproduce sexually and asexually by Spores (or Dermatophytes).
2. Yeasts Shape: Round or oval.
Reproduction: Reproduce by budding and form Blastospores
.
Example: Cryptococcus neoformans.
3. Yeast-like Fungi
Occur as budding yeasts or elongated unbranched filaments (Pseudomycelium). / Example: Candida.
4. Dimorphic Fungi
Behavior: Change morphology based on temperature. / Room Temp: Filamentous morphology.
In Body (with infection): Yeast or Yeast-like form.
II. Medical Mycology
Definition: Study of mycoses or fungi of man and animals.
​Pathology: Cause Leukocytic inflammation.
Key Note: They are not Contagious.
Classification of Mycoses (According to Affected Body Site)
Superficial Mycoses: Restricted to the outer layer (ex. Epidermis, nails, hair, dermatophytosis).
Subcutaneous Mycoses: Below the skin.
Systemic Mycoses: Transmission occurs by inhalation of Fungal Spores.
Components of the Virion
Genome: Viral nucleic acid; encodes viral proteins; requires host cell enzymes; single or double strand DNA/RNA.
Capsid : (Naked) Protein outer layer made of Capsomeres. / Contains VAP (Viral Attachment Protein) for target cell binding.
Role: Protects genome, gives shape, endures harsh conditions.
Transmission: Can be transmitted by the Faecal-Oral route (endures destruction in feces).
Envelope (Enveloped) Composed of Proud Lipids. Contains VAP.
Environmentally labile (fragile).
Transmission: Transmitted in fluids and secretions. / Cannot survive harsh conditions in the GIT.
Examples of Viruses
RNA Viruses Influenza, Polio, AIDS, Rubella (German Measles), Varicella (Chicken pox).
DNA Viruses Human Papilloma Virus (Warts), HBV (Hepatitis B).
IV. Classification and Detection
​Size (Small, Medium, Large)
​Morphology (Icosahedral, Helical, Complex)
.​
Nucleic Acid (DNA, RNA)
.​
Structure (Enveloped, Naked)
​.Disease (e.g., Hepatitis viruses)
​Organ Tropism (e.g., Viruses in GIT)
Hepatitis Notes:
​Hepatitis (A, E): Transmitted by the Feacal-Oral route.
​Hepatitis (B, C, D): Transmitted by the Parental/Sexual route.
​Two Ways to Elaborate/Detect Viruses
​
ELISA: Used to detect the virus as an Antigen or Antibody.
​PCR: Used to detect the Viral Genome.