and answers verified to pass
2025/2026
Describe a virus. - correct answer ✔• very small (10-400nm) -not cells -genome surrounded by a
protective protein coat -depend on host cell to provide machinery they need to reproduce -formed from
assembly of newly synthesized components made in a host cell
Can all viruses infect any tissue or any host? - correct answer ✔No
How are viruses classified? - correct answer ✔Shape, genetic material (RNA or DNA), enveloped, non-
enveloped
Describe an enveloped virus. - correct answer ✔Have an external membrane surrounding the capsid
protein. Generally easily destroyed by common disinfectants, detergents, freezing, and thawing, as the
lipid membrane is easily disrupted.
Describe a non-enveloped virus. - correct answer ✔No membrane around their protein capsid. Very
difficult to destroy with commonly used disinfectants. Examples: Canine Parvovirus, Feline
Panleukopenia, Feline Calicivirus.
What is meant by the term "naked virus"? - correct answer ✔virus lacking the viral envelope. Pertain to
those that only have nucleocapsid, which is a protein capsid that covers the genome of the virus.
How are viruses transmitted? - correct answer ✔Direct contact (person-to-person), Indirect contact
(contaminated food, water, bodily fluids, or other objects)
Virus - correct answer ✔• enters the host via mucous membranes of the respiratory, gastrointestinal or
urogenital tract • recognizes and binds to specific receptors on the surface of the cell.
, When do clinical signs develop after a host is infected with a virus? Right after infection? - correct
answer ✔No. Clinical signs develop during the release stage of the viral infection. Virions go on to infect
other cells and the cycle begins again. Once enough normal cells are destroyed, clinical signs emerge.
Enveloped viruses leave the cell by budding without destroying the host.
What are the possible effects of viral infections on cells? - correct answer ✔• Most infections cause no
obvious damage to the host • Cell ruptures (lyse) releasing the viral particles • Cell remains intact and
the viruses migrate out of the cell. Virus causes the cell to malfunction and clinical signs are due to this
malfunction vs cell death. Example: Rabies virus • Some viruses can cause the cell to transform into a
cancerous (malignant) cell. Example: Feline Leukemia Virus
Define "primary infection" as it relates to disease. - correct answer ✔Viral infection is known as the
Primary infection - damages the cells.
What is meant by a "secondary infection"? - correct answer ✔Bacteria move in and increase in
numbers = Secondary infection - clinical signs such as pus discharge from the eyes and nose. Infection
that is secondary to cause of illness
What are the possible outcomes of viral infections? - correct answer ✔• Most infections cause no
obvious signs • Acute infection / illness - virus replicates, clinical signs develop, recovery or death •
Chronic infection • Carriers - some animals remain infected with a virus and can shed viral particles
without showing clinical signs themselves (Asymptomatic) • Latent infection - The virus may be hiding
(dormant) in specific tissue and will become reactivated with stress, malnutrition, or concurrent illness.
Examples: Herpes virus in humans (cold sores and genital herpes); Feline upper respiratory viruses
Understand the steps of viral replication. - correct answer ✔Attachment (adsorption) stage ->
Penetration step -> uncoating of genetic material -> replication -> assembly -> Release stage "Naked
Virus" -> Release stage Enveloped virus
What is meant by a "latent infection"? - correct answer ✔Virus is hiding dormant until stress occurs
which causes the infection/virus to emerge/become reactivated. Ex) Feline respiratory viruses