Lecture 12: Host microbe interactions

Question 1

Chronic infection

Answer 1

Continuous production of low levels of virus particles and the carriers can transmit virus regardless of a lack of symptoms

Question 2

Latent infection

Answer 2

Viral genome remain silent and host cell and can reactivate to cause productive infection

Question 3

Hepatitis B/C

Answer 3

Infects hepatocytes (liver cells) and are chronic infections, EX cirrhosis or hepatocellular or carcinoma or hepatitis

Question 4

Cirrhosis

Answer 4

Scarring of liver

Question 5

Herpes simplex virus type 1/2

Answer 5

Infect or hang out at neurons of sensory ganglia (cranial nerve) and are latent infections, EX oral or genital herpes

Question 6

Varicella zoster

Answer 6

Latent infection that hangs out at satellite cells of sensory ganglia, EX chickenpox or shingles

Question 7

Cancer

Answer 7

Caused by mutations in three classes of genes: DNA repair enzymes, protooncogenes, tumor suppressor

Question 8

Proto-oncogene

Answer 8

Molecular switches that tell cells to divide and when mutated it is called oncogene (switched on forever)

Question 9

Tumor suppressor

Answer 9

Normally inhibit growth in cell division, but when mutated, it will not be able to repair cells and cause unregulated growth in cells

Question 10

Provirus

Answer 10

Latent virus

Question 11

Viral oncogenes

Answer 11

Viruses that can carry oncogenes

Question 12

Microbiome

Answer 12

Collection of all microbial species on an individual

Question 13

The human microbiome

Answer 13

• Colonization begins at birth
• Composition is different among individual and overtime
• biome changes based on physiological state

Question 14

Benefits of human microbiome

Answer 14

• Protect against pathogens
• Resident my girls have been attachment to disease causing microbes tissues, consume the available nutrients and therefore compete with and produce toxic chemicals
• Aids in digestion such as increase nutrients and break down fiber

Question 15

Dysbiosis

Answer 15

Imbalance in the normal microbiota

Question 16

Microbial cloud

Answer 16

Different species exist on different individual

Question 17

Koch’s postulates

Answer 17

1) The micro organism must be present in every case of the disease but not in healthy hosts
2) Micro organism must be grown in a pure culture from diseased hosts
3) The same disease must be produced when a pure culture of the organism is introduced into susceptible hosts
4) he seem micro organisms must be recovered from the experimentally infected hosts

Question 18

Limitations of Koch’s postulates

Answer 18

• Some people are asymptomatic
• Latent viruses
• some microorganisms cannot be grown in a pure culture

Question 19

Pathogenicity

Answer 19

• Primary pathogen: cause disease in healthy individual

- Opportunistic pathogen: cause disease when body’s defenses are compromised

Question 20

Pathogenicity principles

Answer 20

• Virulence: Degree of pathogenicity

- Virulence factors: proteins and other molecules produced by a microorganism

Question 21

Infectious disease principles

Answer 21

• pathogenicity
• infection
• localized

Question 22

Infection

Answer 22

• Communicable of contagious
• Infectious dose is number of microbes necessary to establish infection (ID50 is minimum number of cells/viruses needed to cause infection in 50% of population)

Question 23

Distribution of pathogen

Answer 23

Systemic infection: agent spread throughout body

Categories: bacteremia, toxemia, viremia (all can lead to sepsis)

Question 24

Bacteremia

Answer 24

Bacterium in the blood

Question 25

Toxemia

Answer 25

Toxin in blood

Question 26

Viremia

Answer 26

Virus in bloodstream

Question 27

Sepsis

Answer 27

Life threatening inflammation -> blood loses fluid -> blood pressure drops -> heart rate elevated -> not enough oxygen in tissues -> multiple organ failures

Question 28

Pathogenesis mechanism

Answer 28

- Produce toxins that are ingested - Colonize mucous membranes and produce toxin - invade hist tissues, avoid defenses - invade host tissues, produce toxins - pathogens adhere to host tissues via adhesins

Question 29

Adhesins

Answer 29

Attach to host cell receptor which are located at tips of fimbriae/villi

Question 30

Produce toxins that are ingested

Answer 30

Microbes does not grow and we’re on the house that produces toxins that cause illness EX clostridium botulinum

Question 31

Colonize mucous membranes, produce toxins

Answer 31

Colonization often done through biofilm formation EX vibrio cholera

Question 32

Secretion systems

Answer 32

Found in gram bacteria - don’t can inject molecules other than proteins - Type 3 secretion system (injectisome)