Microbio Health Sciences - Viral Diseases

What virus targets dendritic cells, macrophages, and CD4+ T cells?

Human Immunodeficiency Virus (HIV)

What are the two strains of Human Immunodeficiency Virus?

HIV1 and HIV2

What type of virus is Human Immunodeficiency Virus?

Retrovirus

How many identical, positive RNA genome molecules does HIV have?

Two

What type of envelope does HIV have?

Phospholipid envelope

What are the spikes on the HIV virus called?

gp120 glycoprotein spikes

What two enzymes does HIV carry?

Reverse transcriptase and integrase

*Reverse transcriptase makes a lot of errors when copying RNA into DNA --> proteins on viral surface change frequently, becoming resistant to antiviral compounds fast

Transmission of HIV

Sexual contact

Blood transfusion

Needle sharing

Mother to infant (pregnancy, childbirth, breastfeeding)

What cancer develops in HIV patients?

Kaposi's sarcoma; forms in the lining of blood vessels and lymph vessels

How does HIV avoid detection and destruction by the immune system?

Remaining as a latent provirus within the host cell nucleus

Moving from cell to cell by cell-cell fusion

Undergoing a high rate of mutation

What is Antiretroviral Therapy (ART) for HIV?

Multiple drugs given simultaneously to lower viral load and minimize the survival of resistant strains

NO vaccine available for HIV

Measles (Rubeola)

Transmission via respiratory route

Highly contagious

Prevented by the MMR Vaccine

What are the symptoms of Measles?

Cold/flu-like symptoms, macular rash

Koplik's spots appear before measles rash appears

What are the complications of Measles?

Acute measles encephalitis, Subacute sclerosing panencephalitis (SSPE)

Rubella (German Measles)

Transmission via respiratory route

Prevented by MMR vaccine

What are the symptoms of Rubella?

macular rash, light fever, milder than measles

Can Rubella cross over the placenta?

Yes. It leads to Congenital Rubella Syndrome, causing fetal damage, deafness, heart defects, and mental retardation in 35% of cases

Chickenpox (Varicella)

Transmission via respiratory route

Caused by HHV-3

Virus moves up peripheral nerve, into the nerve cell of root ganglia, and become latent

Prevented by live, attenuated vaccine

Symptoms of Chickenpox

Pus-filled vesicles

Damage to blood vessels

What are the complications of Chickenpox?

Reye's Syndrome

Causes vomiting and brain dysfunction

Shingles (Herpes Zoster)

Reactivation of latent VZV

Moves from ganglia, down peripheral nerves, to skin

Individuals with Shingles can shed VZV and infect nonimmune individuals with chickenpox

Stronger version of live attenuated vaccine for chickenpox used to protect against Shingles (Shingrix vaccine)

What are the causes and symptoms of Shingles?

Stress or lowered immunity (most common in adults)

Painful, pustular lesions over a dermatome that is limited to one side of the body

Smallpox

Contageous, disfiguring, and deadly disease that was completely eradicated from human population by vaccination. A potential bioterrorism agent

How is smallpox transmitted?

Respiratory route --> bloodstream --> infects internal organs and the skin

What are the hosts for smallpox?

Only humans. No animal host reservoirs

Herpes Simplex Virus (HSV)

HSV-1 --> cold sores spread by oral contact

HSV-2 --> genital herpes spread sexually

Latent virus in nerve gangila

Virus can be shed even when there is no lesion present

What are the complications of HSV?

Herpes encephalitis: virus spreads to brain, treated w/ acyclovir

Neonatal herpes: leads to permanent brain, eye damage, or even death; resulted from transmission during childbirth

Human Papilloma Virus (HPV)

Over 200 types - most cause common skin warts

Some cause genital warts and infect mucous membranes

14 types related to cancers (HPV-16 and HPV-18)

How is HPV prevented?

Gardasil-9 vaccine; prevents 9 HPV strains

Does not treat an existing HPV infection, HPV-related disease, or cancer

Epstein-Barr Virus (EBV)

HHV-4 --> infects B cells of immune system and causes mono

Becomes latent in B lymphocytes after recovery of initial infection

Transmitted via saliva

What are the complications of EBV?

Burkitt's lymphoma (common in children in Africa, AIDS patients in US)

Nasopharyngeal carcinoma

Cytomegalovirus (CMV)

HHV-5 --> infects leukocytes and establishes latency in them

How is CMV transmitted?

Sexually, via blood, saliva, transplanted tissue, across the placenta

What are the complications of CMV?

Cytomegalic inclusion disease (CID) in babies

Problems in immunocompromised patients

Threat to transplant recipients --> drugs suppress immune system and cannot fight off virus easily

Rhinovirus

Common cause of cold

Thrive in temperatures lower than body temperature

Too many strains --> cannot produce effective vaccine

Antibiotics not useful