Virus-Host cell virus interaction

What is an infectious disease?

Diseases caused by a MO

What is contamination?

Entry of the MO into the host.

What is an infection?

It is the pathological consequence at the tissue level or presence/multiplication of a MO.

What is a pathogen?

MO capable of causing the disease.

What is opportunistic pathogen?

MO that can be pathogenic in certain cases.

What is virulence?

It indicates the degree of pathogenicity of a MO and the severity of the disease (quantitative).

Which are the mainly 3 roles of MO?

Symbiosis, commensalism, parasitism

How the MO are trasmitted?

1. Direct contact (HIV)
2. Indirect contact (Flu)
3. Droplets (Flu)
4. Airborne (Flu)
5. Fecal-oral (rotavirus)
6. Pregnancy, delivery, breastfeeding (HIV)
7. Latrogenic (HIV)
8. Arthropod vector (zika)

Which are the open doors for the infection?

1. Respiratory airway (flu)
2. Digestive oral route (rotavirus)
3. Cutaneous route (HIV)
4. Conjunctival route (adenovirus)
5. By inoculation (zika)
6. Urogenital tract (HIV)

How the virus can be trasmitted in the skin?

1. Arthropod bites (arbovirus)
2. Minor lesions (HPV)
3. Major lesions (rabies)

How the virus can be trasmitted in the respiratory tract?

Aerosol production by couphing and sneezing

In what are divided the diseases that are transmitted through respiratory tract?

1. Local respiratory tract infections (orthomyxovirus)
2. Generalized infections with resp as their staring point (rubella)

How the virus can be trasmitted in the alimentary tract?

Through water and food contaminated released into the stool

What these virus (trasmitted from alimentary tract) are resistant in?

Acidic pH, proteases, bile salts

In what are divided the diseases that are transmitted through alimentary tract?

1. Localized infectiojns: rotavirus
2. Generilized infections: poliovirus

In what are divided the diseases that are transmitted through urogenital tract?

1. Localized (papillomavirus=condylomas, HSV-2=genital herpes, adenovirus=cystitis)
2. Generalized (HIV)

How the virus can be released from the body?

2. Saliva (CMV)
3. Respiratory secretions (Flu)
4. Stool (rotavirus)
5. Urine (CMV)
6. Skin rash (HSV-1)
7. Blood (HIV)
8. Maternal milk (HIV)
9. Genital secretions (HIV)

What is the localized infection?

Infection that remains localized to epithelial cells at the primary site of infection

What is viremia?

Passage through the lymphatic system, local lymph nodes and blood dissemination

What is generalized infection (systemic)?

After primary infection, passage into the lymphatic system and into the bloodstream and reaches the target organ

Host’s risk factors

1. Extreme ages
2. Pregnancy
3. Hormonal status
4. Innate or acquired immune deficiency
5. Undernutrition/ malnutrition
6. Chronic pathologies
7. Genetic factors
8. Travel to endemic areas
9. Contact with animals

Which are the factors involved in the localization of the disease?

1. Temperature sensitivity of the virus
2. Lack of permissiveness of cells
3. Polarization of epithelial cells

Which are the different types of viral infections?

1. Acute (after acute we can have)
2. Latent (primary infection)
3. Chronic (continues production)
4. Transforming (into cancers)
5. Cure and elimination of the virus

Which are the stages of acute infection (cured)?

1. Virus replication
2. Elimination of the virus by the immune system

Which are the characteristics of a persistent infection?

1. Maintaing the viral genome in the cell
2. Sufficient number of surviving cells (low cytopathic effect)
3. No elimination of the virus by the IS
4. 2 categories: latent, chronic

What the characteristics of latent infection?

1. essential for DNA viruses (more stable)
2. Trasmission when it is reactivated

What the characteristics of chronic infection?

1. continous replication
2. trasmission for long periods
3. viral genome maintained in the host

Which are the defence lines?

1. Innate immunity (immediate, limitation of the damage, adaptive activation)
2. Adaptive immunity (adapts, memory)

What happens in the innate response?

1. IgM>IgG
2. Weak affinty
3. Low level of somatic hypermutation

What happens in the secondary response?

1. Isotypes IgG and IgA
2. Strong affinity
3. High level of somatic hymermutation
4. Memory

Which are the cell-virus interactions? (virus edition)

1. depends on cell for replication
2. diverts the fuction of the cell for their benefit
3. promotes survival of the host cell

What are the cell-virus interactions? (cell edition)

1. innate intracellular mechanism
2. soluble immune system factors
3. adaptive mechanisms

How the virus is survived in the host cell?

1. virus replication
2. cell cycle blocking
3. immortalization of cells
4. modulation of cell gene expression
5. blockage of splicing of the cell mRNA

How to prevent viral infections?

1. hygiene
2. policy
3. septic isolation of infected or carrier cells
4. vaccination
5. prevention