Key Terminology & Definitions - Virology, Mycology Flashcards
Examples of zoonotic viruses
HIV/AIDS, influenza, Measles, Coivd-19
Non-structural proteins
Encoded in viral genome, not packaged within virion, synthesised during replication, suppress innate/and or adaptive immunity
Enveloped viruses
Disinfected by organic detergents e.g. Rabies virus
RNA viruses
Higher mutation rate e.g. Hepatitis C virus
Large dsDNA viruses
More stable in the environment (not making more, sit there and don’t get degraded) e.g. African swine fever virus
Segmented viruses
Sudden emergence of new strains due to genetic drift e.g. Influenza virus
Virion
Entire virus particle - outer protein shell (capsid), inner core of nucleic acid (RNA/DNA)
Structural viral proteins
To make more virions + may help out with replication
Non-structural viral proteins ‘helper proteins’
Viral factory proteins, interfere with host protein synthesis, counteract immune responses
Foot-and-mouth disease virus
Airborne, direct contact, epithelial cells tongue (1^y amplification), mouth, coronary bands
Bluetongue virus
Insect transmitted - culicoides biting midges, during blood-feeding placed in skin, endothelial cells of capillaries in many organs (directly into blood)
Rabies virus
Bites/saliva - neurones (1^y replication —> CNS —> brain), salivary gland cells
Viral shedding
Release of infectious virus particles
Infectious period of time
From point of shedding of virus from animal through clinical disease stages for animal until virus isn’t shedded - shedding + disease doesn’t always occur throughout transmission steps
Labile
= Changes quickly + spontaneously
Cells that multiply constantly throughout life, only alive for short period of time e.g. Rabies virus won’t survive for more than a few hours outside host cell
Envelope viruses
Most labile, can be easily destroyed, membrane pops in UV light/heat damage/detergent, needs to be inside all the time
Fungi
Eukaryotic - cells w/ nuclei, can be commensals (normal flora), grow anaerobically, four groups
Ascomycota
‘Sac’ fungi (yeasts, truffles)
Basidiomycota
‘Club’ fungi (mushrooms)
Zygomycota
Bread moulds
Deuteromycetes
‘Fungi imperfecti’ - most fungi of veterinary importance
Filamentous (fungi morphology)
Branches, growing out
Yeast (fungi morphology)
Individual, oval, spherical
Candida albicans
Yeast as a commensal (in oral cavity + urogenital tract) —> becomes filamentous as a pathogen (causes thrush) (dimorphic)
Histoplasma
Filamentous in the environment —> becomes yeast in the body (inc temp) (dimorphic)
Mycosis
Tissue invasion - superficial, on surface (+ mm + subcutaneous), systemic (usually respiratory or GIT)
Mycotoxicocosis
Toxin production
Dermatophytes
Fungi that require keratin for growth, cause skin diseases, three groups based on the habitat
Zoophilic
Obligate pathogens, mainly infect animals + also people
Anthropophilic
Obilgate pathogens, only infect humans
Geophilic
Occur naturally in soil (with decomposing hair/feathers), can infect animals/people
Microsporum and trichophyton
Main species of dermatophytes
Ringworm
Invade superficial keratinised structures (skin, hair, claws), transmission via direct (or indirect) contact with spores e.g. Microsporum canis (cats main source), zoonotic
Saprophytic
Free-living in the environment
Aspergillus spp.
Saprophytic, wide distribution, A. fumigatus - most common species causing disease, respiratory pathogen - acquired by spore inhalation, most commonly from poor quality hay, compost heaps, contaminated bedding
Yeasts
Found in the environment, often on plants/as commensals on skin/mms.
Cause opportunistic infections e.g. Candida (C. albicans), Cryptococcus neoformans, Malassezia pachydermatis
Histoplasma
Associated with soil contaminated with bird/bat droppings, spores usually enter host via respiratory route, mould (filamentous form) —> yeast form in host (dimorphic), granulomatous lesions form (nodules), mimics TB in humans, H. capsulatum = cat/dog respiratory disease/emacication
Mycotoxin
Produced by toxigenic fungi on crops, pasture or stored feed under certain conditions (moisture, temp, O2 levels), many heat stable (processing can’t remove), ingested by animals e.g. Aflatoxins produced by Aspergillus flavus (hepatotoxicity) and Ergotamine produced by Claviceps purpurpea (neurotoxicity)
