Key Terminology & Definitions - Virology, Mycology

Question 1

Examples of zoonotic viruses

Answer 1

HIV/AIDS, influenza, Measles, Coivd-19

Question 2

Non-structural proteins

Answer 2

Encoded in viral genome, not packaged within virion, synthesised during replication, suppress innate/and or adaptive immunity

Question 3

Enveloped viruses

Answer 3

Disinfected by organic detergents e.g. Rabies virus

Question 4

RNA viruses

Answer 4

Higher mutation rate e.g. Hepatitis C virus

Question 5

Large dsDNA viruses

Answer 5

More stable in the environment (not making more, sit there and don’t get degraded) e.g. African swine fever virus

Question 6

Segmented viruses

Answer 6

Sudden emergence of new strains due to genetic drift e.g. Influenza virus

Question 7

Virion

Answer 7

Entire virus particle - outer protein shell (capsid), inner core of nucleic acid (RNA/DNA)

Question 8

Structural viral proteins

Answer 8

To make more virions + may help out with replication

Question 9

Non-structural viral proteins ‘helper proteins’

Answer 9

Viral factory proteins, interfere with host protein synthesis, counteract immune responses

Question 10

Foot-and-mouth disease virus

Answer 10

Airborne, direct contact, epithelial cells tongue (1^y amplification), mouth, coronary bands

Question 11

Bluetongue virus

Answer 11

Insect transmitted - culicoides biting midges, during blood-feeding placed in skin, endothelial cells of capillaries in many organs (directly into blood)

Question 12

Rabies virus

Answer 12

Bites/saliva - neurones (1^y replication —> CNS —> brain), salivary gland cells

Question 13

Viral shedding

Answer 13

Release of infectious virus particles

Question 14

Infectious period of time

Answer 14

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

Question 15

Labile

Answer 15

= 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

Question 16

Envelope viruses

Answer 16

Most labile, can be easily destroyed, membrane pops in UV light/heat damage/detergent, needs to be inside all the time

Question 17

Fungi

Answer 17

Eukaryotic - cells w/ nuclei, can be commensals (normal flora), grow anaerobically, four groups

Question 18

Ascomycota

Answer 18

‘Sac’ fungi (yeasts, truffles)

Question 19

Basidiomycota

Answer 19

‘Club’ fungi (mushrooms)

Question 20

Zygomycota

Answer 20

Bread moulds

Question 21

Deuteromycetes

Answer 21

‘Fungi imperfecti’ - most fungi of veterinary importance

Question 22

Filamentous (fungi morphology)

Answer 22

Branches, growing out

Question 23

Yeast (fungi morphology)

Answer 23

Individual, oval, spherical

Question 24

Candida albicans

Answer 24

Yeast as a commensal (in oral cavity + urogenital tract) —> becomes filamentous as a pathogen (causes thrush) (dimorphic)

Question 25

Histoplasma

Answer 25

Filamentous in the environment —> becomes yeast in the body (inc temp) (dimorphic)

Question 26

Mycosis

Answer 26

Tissue invasion - superficial, on surface (+ mm + subcutaneous), systemic (usually respiratory or GIT)

Question 27

Mycotoxicocosis

Answer 27

Toxin production

Question 28

Dermatophytes

Answer 28

Fungi that require keratin for growth, cause skin diseases, three groups based on the habitat

Question 29

Zoophilic

Answer 29

Obligate pathogens, mainly infect animals + also people

Question 30

Anthropophilic

Answer 30

Obilgate pathogens, only infect humans

Question 31

Geophilic

Answer 31

Occur naturally in soil (with decomposing hair/feathers), can infect animals/people

Question 32

Microsporum and trichophyton

Answer 32

Main species of dermatophytes

Question 33

Ringworm

Answer 33

Invade superficial keratinised structures (skin, hair, claws), transmission via direct (or indirect) contact with spores e.g. Microsporum canis (cats main source), zoonotic

Question 34

Saprophytic

Answer 34

Free-living in the environment

Question 35

Aspergillus spp.

Answer 35

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

Question 36

Yeasts

Answer 36

Found in the environment, often on plants/as commensals on skin/mms.
Cause opportunistic infections e.g. Candida (C. albicans), Cryptococcus neoformans, Malassezia pachydermatis

Question 37

Histoplasma

Answer 37

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

Question 38

Mycotoxin

Answer 38

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)