fungal cell walls

Fungal Cell Walls

• Structure of Cell Walls: Fungal cell walls are not composed of peptidoglycan; instead, they are primarily made of chitin.

Viruses Overview

• Specificity of Viruses: Different viruses are specific to their hosts; they can infect bacteria (bacteriophages) or other cells.

• Virus Entry into Host:

  • Entry Mechanism: Viruses must enter their host cells to infect them, typically through endocytosis.

  • Envelope Fusion: Envelope viruses can fuse their membranes with the host cell membrane during entry.

Viral Replication Process

• Genetic Material Injection: After entry, viruses inject their genetic material into the host cell to begin replication.

  • DNA Virus Replication: DNA viruses replicate in the nucleus of the host cell.

  • RNA Virus Replication: RNA viruses replicate outside the nucleus.

Attachment Mechanism

• Receptor Binding: The attachment process involves specific receptors on the host cell that viral proteins bind to.

  • Viral Proteins: Proteins such as spike proteins, glycoproteins, and envelope proteins assist in binding.

    • Example receptors include sialic acid.

• Tropism: Tropism refers to the specificity of a virus for certain tissues or cells, indicating which types of tissues an individual virus can infect.

  • Cellular Tropism: Can refer to specific tissues within a host (e.g., lung, heart, brain) or specific species (e.g., dog, human, cat).

Viral Release and Cycle

• Release of New Viruses : Enveloped viruses can exit the host cell through a process that may involve obtaining parts of the host cell's membrane.

• Impact of Antibiotics on Viruses:

  • Antibiotics Target: Antibiotics are ineffective against viruses as viruses do not possess their own ribosomes. Using antibiotics may target human cells instead.

• Antiviral Drug Mechanism:

  • Targeting Enzymes: Some antiviral agents target viral enzymes that are crucial for replication, such as those involved in phosphate group mobilization.

  • Entry Requirement: Antiviral drugs must first penetrate the plasma membrane of host cells to be effective.

• Limitations: Antiviral drugs are not perfect as they must successfully enter host cells and target viral functions without harming human cells.