Lecture 3 viruses and protozoa

Question 1

Viruses

Answer 1

Most common cause of illness
Both primary & secondary illness

Overlapping/similar symptoms
Requires detailed diagnostics

Multiple transmission routes
Person to person (horizontal), mother to child (vertical), animal to person (zoonotic)

Question 2

protozoa are

Answer 2

Intracellular parasites that cause morbidity and mortality worldwide
In both developing & western countries

Many of the most prevalent and deadly human diseases are caused by a protozoan infection!
Including African sleeping sickness, amoebic dysentery, & malaria

Question 3

viruses are what type of parasites and what does this mean

Answer 3

Obligate intracellular parasites

this means that the virus doesn’t grow, it only replicated inside the host cell, it often uses the host cells metabolism

Question 4

state the viral cycle steps (5 marks)

Answer 4

1) attachment
2) penetration/entry
3) uncoating
4) replication
5) assembly
6) release

Question 5

State and describe the steps in the viral life cycle (5 marks)

Answer 5

do it on a whiteboard

Question 6

What 2 things does the virus need to be good at?

Answer 6

Transmission
Host to host transport (coughing)

Symptoms
Cellular impacts

Question 7

different transmission processes

Answer 7

Coughing
Hand hygiene
Can get it from body contact
Can be from blood
Can be from vectors (insects, dog bites, ticks)

Question 8

You can get a range of symptoms such as

Answer 8

Cell destruction
Changes to gene expression
Immune response degradation

Some viruses can hide within immune system

Question 9

What are different outcomes of viral infection (4) describe them

Answer 9

1)TRANSFORMATION- you can get the cell being converted to a tumour cell which leads to tumour cell division

2) LYSIS - cell death and release of virus

3) PERSISTENT INFECTION - slow release of virus without cell death

4) LATENT INFECTION - virus is present bit later emerges into a lytic infection

Question 10

Oncogenic DNA viruses (TUMOUR CAUSING)

Answer 10

END IN DAE APART FROM RETROVIRIDAE

Adenoviridae
Heresviridae
Poxviridae
Papovaviridae
Hepadnaviridae

Question 11

Oncogenic viruses cont. Oncogene theory

Answer 11

first hit, Repressor gene is not faulty

Second hit – insersion of viral material into Repressor gene - means onco gene expresses and so cells generate with tumoir

Question 12

Classification of viruses - the Baltimore system

Answer 12

look at picture

Question 13

DNA Viruses of Importance to Humans
which are the two

Answer 13

Herpesviridae
Poxviridae

Question 14

examples of herpesviridae

Answer 14

Herpes simplex type I (HSV-1) - COLD SORES!
Herpes simplex type II (HSV-2)
Varicella-zoster virus (VZV/HHV-3) - Chickenpox

Cytomegalovirus (CMV/HHV-5)
Herpesvirus type 6 (HBLV/HHV-6)
Herpesvirus type 7 (HHV-7)

ONCOVIRUSES:
Epstein-Barr virus (EBV/HHV-4) Epstein-Barr virus
Kaposi’s sarcoma herpesvirus (KSHV/HHV-8).

Question 15

Herpesviridae what is common

Answer 15

latency is common as is resurgence (so virus will remain, so it can cause disease later in date)

cold sores (HSV-1)
and chicken pox - shingles

> 90% of adults infected with one of these

Often asymptomatic
Age related
HSV-1 by 1-2 years of age
HSV-2 infection on the onset of sexual activity

Question 16

infection of hsv - types

Answer 16

Through a break in the mucous membranes
Mouth or throat
Cold sores

Via the eye or genitals
Genital herpes

Directly via minor abrasions in the skin.
Herpes whitlow (fingers)
Herpes gladiatorum (often found in wrestlers!)

Question 17

Reactivation & Latency - of hsv - 1

Answer 17

When latent viral DNA is not integrated into host genome
Limited expression of viral genes

Reactivation can be due to:
Physical (e.g., injury, ultraviolet light, hormones, menstruation)
Psychological (e.g., stress, emotional upset).

Question 18

symptoms of hsv - 1

Answer 18

Fluid filled vesicles
More dangerous in the immunocompromised

Question 19

poxviridiae examples and what does it cause diseases in

Answer 19

Causes diseases in vertebrates and invertebrates
Smallpox
Large complex virus
Cowpox
Monkey Pox

Question 20

Historical Impact - of poxviridae

Answer 20

Smallpox Killed 400,000 Europeans pa during the 18th century
It was Responsible for 30% of all blindness.

There was a High mortality rate
20–60% of adults
>80% of infected children

In 1967 2 million people died (pox virus)

Disease eradicated worldwide by immunization in 1977

Question 21

RNA viruses - examples

Answer 21

Poliovirus
Norovirus
Influenza
Rotavirus
Hantavirus
Ebola
Coronaviruses (CoVs)

Question 22

RNA VIRUS - poliovirus

Answer 22

Enterovirus.
+ stranded RNA virus
Naked (no envelope around it)
Immunisation
WHO eradication programme

Question 23

Poliomyelitis
caused by what?
transmission?
symptoms?
Prevention?

Answer 23

caused by poliovirus
transmission is by ingestion of water
symptoms are sore throat and nausea
viremia may occur but this is in less than 1% of patients
prevention is vaccination

Question 24

Parasite vs Pathogen

Answer 24

Not always clear if protozoa are parasites or pathogens
Insect transmitted protozoa are more like parasites than pathogens
Systemic long-term infections
Intracellular phase
Hard to treat

Pathogens are often fecal oral transmitted
Theyre Shorter term diseases

Question 25

Faecal Oral Transmission

Answer 25

Giardia Found in intestinal tracts of animals and in the environment (Beaver fever) Amoebic Dysentery can cause Cryptosporidium

Question 26

Acanthamoeba and Naegleria

Answer 26

Acanthamoeba sp Damage cornea Cause fatal encephalitis Brain & spinal cord infections

Question 27

Trichomonas vaginalis

Answer 27

Most common protozoan causing human disease in industrialized nations Lives in the genitourinary system of men and women Transmitted almost exclusively via sex Infection of women results in vaginitis Infection of men is typically asymptomatic

Question 28

Toxoplasma

Answer 28

T. gondii is causative agent of toxoplasmosis Most widely distributed parasites Wild and domestic mammals and birds are major reservoir Infection due to consumption of undercooked meat containing the parasite Ingestion or inhalation of contaminated soil can also occur The protozoan can cross the placenta and infect the fetus

Question 29

The life cycle of Toxoplasma gondii

Answer 29

Most infections are asymptomatic Toxoplasmosis develops in a small number of people Fever-producing illness combined with other symptoms Usually is a self-limited infection Toxoplasmosis is more severe in two populations AIDS patients Feotus

Question 30

Trypanosoma cruzi

Answer 30

Causes Chagas’ disease Endemic in Central and South America Opossums and armadillos are the primary reservoir Transmission occurs through bite of insects in genus Triatoma “Kissing bugs” feed preferentially from blood vessels in the lips Parasite-induced heart disease is a leading cause of death in Latin America

Question 31

Trypanosoma brucei

Answer 31

Causes African sleeping sickness The insect vector is the tsetse fly Three stages Site of the fly bite becomes a lesion with dead tissue Fever, lymph node swelling, and headaches Meningoencephalitis Infections characterized by cyclical waves of infection Clearing tsetse fly habitats reduce the cases of disease

Question 32

Leishmania causes

Answer 32

Causes leishmaniasis Endemic in parts of the tropics and subtropics Wild and domestic dogs and small rodents are common hosts Transmitted by sand flies

Question 33

Plasmodium - causative agent of

Answer 33

Causative agent of malaria Four species cause malaria P. falciparum, P. vivax, P. ovale, and P. malariae Malaria is endemic throughout the tropics and subtropics Mosquitoes are vector for Plasmodium The Plasmodium life cycle has three prominent stages

Question 34

Malaria Vaccine

Answer 34

Two vaccines Both target the first stage of the parasite's lifecycle Before it gets to the liver Built using proteins from the malaria july 2024 - Vaccine can now be produced at massive scale Has been recommended for use by the WHO