Comprehensive Guide to Viruses, Vaccines, and Retroviral Infections

What are viruses?

Small, non-cellular particles that can't replicate unless inside a living host cell, known as obligate intracellular parasites.

What two components make up a virus?

Genomic material (DNA or RNA) and a capsid (protective structure).

What is the size range of viral genomes?

From a few thousand nucleotide base pairs to roughly 2.5 million nucleotides.

What are Pandovirus, megavirus, and mimivirus known for?

They are exceptions to the general size of viruses, being larger than typical viruses.

What is a virion capsid?

The protective outer layer of a virion that encloses its genetic material.

What types of viral genomes exist?

DNA or RNA; can be linear, circular, or segmented; single or double stranded.

What is a viral envelope?

An additional membrane surrounding the capsid, derived from the host cell membrane.

What distinguishes enveloped viruses from non-enveloped viruses?

Enveloped viruses have a lipid coating from the host cell, while non-enveloped viruses do not.

What is the diameter of the poliovirus?

30 nm and it is non-enveloped.

How do viruses enter host cells?

Through membrane fusion or endocytosis.

What happens during the uncoating process of a virus?

The viral capsid disassembles, releasing the viral genome into the host cell's cytoplasm.

What is the virus life cycle?

Attachment to host, penetration, capsid disintegration, genome transcription/translation, genome duplication, assembly of new viruses, and release.

What is an acute viral infection?

A quick virus replication followed by swift immune clearance and rapid patient recovery.

What characterizes a latent viral infection?

Replication peaks and decreases, making it difficult for the immune system to clear the infection.

What is a chronic persistent viral infection?

Low viral replication with no symptoms, but the host may still be infectious.

What are antiviral drugs used for?

To block various stages of the viral life cycle, including attachment, entry, uncoating, replication, assembly, and release.

What is a bacteriophage?

A virus that infects bacteria, possessing an icosahedral capsid head and a helical tail.

What are the two forms of bacteriophage replication?

Lytic and lysogenic.

What occurs during the lytic cycle of a bacteriophage?

Bacteriophages replicate within the host until lysis, destroying the host bacterial cell.

What is viral titer?

The quantity of virus in a culture, important for planning infectious experiments.

What is the role of spike proteins in viruses?

They recognize and bind to specific proteins on the host cell for attachment.

How do enveloped viruses avoid immune detection?

By picking up the host cell's plasma membrane and proteins during budding.

What is the difference between productive and silent infections?

Productive infections involve active viral replication, while silent infections (latency) have low replication.

What is the significance of the viral envelope in animal viruses?

It aids in entry into host cells and camouflages the virus from the immune system.

What is the diameter of the smallpox virus?

200 nm long with a dumbbell-shaped viral capsid.

What are fusion inhibitors?

Antiviral drugs that block the fusion of viral envelopes with host cell membranes.

What is the role of endocytosis in viral entry?

It allows both enveloped and naked viruses to enter host cells through vesicles.

What happens to the viral genome after entry into the host cell?

It is replicated and translated to produce new viral proteins.

What is the purpose of antiviral drugs that inhibit replication?

To prevent the replication and assembly of new viruses.

What are the steps of lytic replication?

Attachment -> Penetration -> Replication -> Assembly -> Release

What is a prophage?

A bacteriophage DNA integrated into the host cell's genome.

What triggers the lytic cycle in lysogenic bacteriophages?

Environmental stressors can trigger the lytic cycle.

What is active immunity?

Immunity that results from exposure to a disease or antigen, leading to antibody production.

How can active immunity be acquired?

Naturally through infection or artificially via vaccination.

What is passive immunity?

Immunity received from antibodies without the immune system developing them.

How can a newborn acquire passive immunity?

Through antibodies received from the mother via placenta or breast milk.

What are the three types of vaccines?

Microbe subunit, nucleic acid, and whole microbe vaccines.

What is a protein subunit vaccine?

A vaccine containing purified viral proteins that are non-infectious.

What is a virus-like particle (VLP) vaccine?

A vaccine made of assembled viral structural proteins with no genetic material.

What is a live-attenuated vaccine?

A vaccine containing a weakened pathogen that can cause a robust immune response.

What is the MMR vaccine?

A whole microbe vaccine that protects against measles, mumps, and rubella.

What virus causes measles?

Rubeola, a linear, single-stranded, enveloped RNA virus.

How is measles transmitted?

Through airborne particles from an infected individual's cough.

What are the initial symptoms of measles?

High fever, runny nose, and red watery eyes.

What virus causes mumps?

Epidemic parotitis, a linear single-stranded enveloped RNA virus.

How is mumps transmitted?

Through direct contact with salivary or respiratory droplets.

What are the main symptoms of mumps?

Headache, fever, muscle aches, and painful swelling of salivary glands.

What virus causes rubella?

A linear single-stranded enveloped RNA virus known as German measles.

How is rubella transmitted?

Via droplets from coughs of infected persons.

What are the symptoms of rubella?

Fever, flu-like symptoms, cough, conjunctivitis, and a red blotchy skin rash.

What is the varicella virus?

The virus that causes chickenpox, a linear double-stranded enveloped DNA virus.

How is chickenpox transmitted?

Through airborne droplets or direct contact with blisters.

What is shingles?

A reactivation of the varicella zoster virus (VZV) causing localized painful blisters.

What are the first symptoms of shingles?

Severe pain, tingling, or burning localized where the rash will later present.

What complications can arise from measles?

Ear infections, diarrhea, pneumonia, and encephalitis.

What type of precautions are recommended for measles?

Standard and airborne precautions, including the use of N95 masks.

What is the incubation period for measles?

About 7 to 10 days from exposure to onset of rash.

What is the treatment for measles?

Supportive care including rest, hydration, and fever/pain reducers.

What virus causes chickenpox?

Varicella-zoster virus (VZV)

What can trigger the reactivation of VZV?

Stress, decreased immunity, and aging

What is the treatment for mild chickenpox symptoms?

Over-the-counter pain medications

What is the treatment for severe chickenpox symptoms?

Antiviral medication such as acyclovir

What does 'Zoster' mean in Greek?

Belt, referring to the rash produced by viral reactivation

What virus causes smallpox?

Variola virus

What are the two classifications of smallpox?

Variola major and variola minor

How is smallpox transmitted?

Through the air and contact with infected individuals

What characterizes the rash of smallpox?

Raised bumps filled with thick opaque fluid that form scabs

When was the smallpox vaccine developed?

In 1796

What virus causes poliomyelitis?

Poliovirus

What is the structure of the poliovirus?

Single-stranded, non-enveloped RNA virus

What is the primary effect of poliovirus infection?

Destruction of motor neurons leading to paralysis

Who developed the inactivated polio vaccine?

Jonas Salk

What is the oral polio vaccine developed by Albert Sabin?

A live attenuated vaccine

What family of viruses does influenza belong to?

Orthomyxoviridae

What are the three types of influenza viruses?

A, B, and C

What are the key glycoproteins found in the influenza virus?

Hemagglutinin (HA) and Neuraminidase (N)

What is antigenic drift?

Small genetic changes in the virus that alter surface proteins, allowing reinfection

What is antigenic shift?

A sudden change in the virus due to reassortment of genes from different strains

What is the significance of the H1N1 strain?

It caused the swine flu pandemic in 2009

What is the primary transmission method for coronaviruses?

Respiratory droplets

What are the three major outbreaks of severe coronavirus infections?

SARS, MERS, and COVID-19

What is the correlation between age and COVID-19 outcomes?

Increased age is associated with higher rates of hospitalization and mortality

What is the family of viruses that includes SARS-CoV-2?

Coronaviridae

What is the common cold primarily caused by?

Coronaviruses

What are common symptoms of COVID-19?

Symptoms can range from asymptomatic infection to high fever, chills, headache, malaise, body aches, sore throat, loss of smell and taste, nausea, vomiting, and diarrhea.

What long-term complications can arise from COVID-19?

Long-term complications include inflammation of heart tissue, abnormal lung function, acute kidney injury, rash and hair loss, and depression.

What is a cytokine storm?

A cytokine storm is a severe immune reaction where the body starts attacking its own cells and tissues, which can lead to complications like acute respiratory distress syndrome.

What technology is used in COVID-19 vaccines?

COVID-19 vaccines are made using recombinant technology to deliver components of the viral genome to cells, prompting an immune response.

What is the function of mRNA in COVID-19 vaccines?

mRNA encodes for part of the SARS-CoV-2 viral spike protein, which alerts the immune system to create immunity against the virus.

What is a recombinant vector vaccine?

A recombinant vector vaccine delivers double-stranded DNA of the SARS-CoV-2 spike protein in a live viral vector, which prompts an immune response without producing new virions.

What is the purpose of serological tests?

Serological tests are used to test for viral infections but are not diagnostic for active infections.

What does 'variance' mean in the context of viruses?

Variance refers to when a virus mutates, potentially affecting immunity from previous exposure or vaccination.

What type of virus is HIV?

HIV belongs to the viral family Retroviridae and is a linear, single-stranded, enveloped RNA virus.

What is the structure of the HIV virus?

HIV contains two copies of single-stranded RNA enclosed by a conical capsid, surrounded by a viral envelope with glycoproteins gp120 and gp41.

How does HIV enter a host cell?

HIV enters a host cell by binding its gp120 protein to the CD4 receptor and co-receptors CXCR4 or CCR5, leading to endocytosis.

What is reverse transcription in HIV?

Reverse transcription is the process where HIV's reverse transcriptase enzyme converts its RNA genome into DNA.

What happens after HIV DNA integrates into the host genome?

Once integrated, the virus relies on the host's cellular machinery for replication, leading to the assembly and release of new viruses.

What is the treatment for HIV?

Individuals infected with HIV are placed on a regimen of antiretroviral medicines to combat the virus's ability to reproduce.

What is AIDS?

AIDS is defined as a severe loss of the body's immunity, making individuals highly susceptible to opportunistic infections.

How is HIV transmitted?

HIV is transmitted through blood, semen, vaginal secretions, and breast milk, primarily during sexual contact or needle sharing.