Microbiology

Varicella-zoster virus (VZV) is a double-stranded DNA virus belonging to the Herpesviridae family, causing chickenpox and shingles.

Endospores are dormant structures that allow bacteria like Bacillus and Clostridium to survive extreme temperatures, desiccation, and chemical stress.

Spike proteins on viral surfaces recognize and bind to specific receptors on host cells, determining viral tropism and infectivity.

The thick peptidoglycan layer in gram-positive bacteria traps the crystal violet-iodine complex, and absence of LPS distinguishes them from gram-negative bacteria.

Pili and fimbriae are hair-like appendages that facilitate bacterial adhesion to host cells and surfaces, essential for pathogenesis.

Smallpox was declared eradicated in 1980 following intensive global vaccination campaigns, the only human virus to achieve this status.

DNA helicase breaks hydrogen bonds between base pairs to unwind the DNA double helix during replication.

Hemagglutinin (H protein) binds to sialic acid receptors on host cells, initiating viral entry in influenza.

Salmonella typhimurium is a major cause of foodborne illness from poultry, causing acute gastroenteritis.

HAV is transmitted through fecal-oral route, particularly in areas with poor sanitation and hygiene practices.