Micro Lecture 1 (OG)

what are cytopathic effects?

virus-induced damage to the cell that causes morphological alterations

what does cytokine storm syndrome cause?

acute respiratory distress syndrome (ARDS) and respiratory failure

what is remdesivir?

ribonucleotide analogue inhibitor of viral RNA polymerase that interferes with viral RNA-dependent RNA polymerase and evades proofreading (decrease viral RNA production)

how do normal microbiota protect the host?

occupying niches that pathogens might occupy;

producing acids;

producing bacteriocins

what is commensalism?

one organism benefits and the other is unaffected

what is parasitism?

one organism benefits at the expensive of the other

what are opportunistic pathogens?

normal microbiota that take advantage of certain situations that allow them to become pathogenic

what are emerging infectious diseases?

diseases that are newly recognized, increasing in incidence, or showing a potential to increase in the near future

what are prokaryotic cells?

do not have a nucleus or membrane-bound organelles

what are eukaryotic cells?

have a membrane-bound nucleus and organelles

are viruses, viroids, and prions considered living?

no, considered non-living

what do viruses consist of?

consist of either DNA or RNA, surrounded by a protein coat

what are viruses?

obligate intracellular agents that use the machinery and nutrients of host cells to replicate

what are prions?

misfolded versions of normal cellular proteins that cause the normal versions to misfold

what are bacteriophages, or phages?

viruses that infect bacteria

what is the capsid of a viral particle composed of?

capsid composed of simple identical subunits called capsomeres

what are icosahedral viruses?

many triangular shaped sided viruses

what are zoonotic viruses?

they cause zoonoses, which are viruses transmitted animal to human directly

what are arboviruses?

arthropod borne viruses;

spread by arthropods (mosquitos)

what are some diseases caused by arboviruses?

yellow fever, dengue fever, West Nile encephalitis

what are the steps of the infection cycle of animal viruses?

attachment;

genome entry;

synthesis;

assembly;

release

what is attachment (adsorption)?

virus attachment proteins (spikes) bond to receptors on host cell surface, usually glycoproteins on cytoplasmic membrane

what is tropism?

particular viruses much attach to specific receptors which limits the cell types and tissues a virus can infect

how do non-enveloped viruses enter a cell?

cannot fuse, enter by endocytosis

what is entry and uncoating?

entire virion enters the cell, nucleic acid separates from the protein coat in a process of uncoating

what is antigenic drift?

a mechanism for variation in viruses that involves the accumulation of mutations within the genes that code for antibody-binding sites

what are acute infections?

rapid onset, short duration;

burst of virions released from infected host cell;

immune system gradually eliminates virus

what are chronic infections?

continuous production of low levels of virus particles;

carriers may lack symptoms, but still transmit virus

what are latent infections?

viral genome remains silent in host cell;

can reactivate to cause productive infection;

viral genome may be integrated into host cell chromosome as a provirus

what are proto-oncogenes?

stimulate cell growth and division

what are tumor suppressors?

genes that inhibit cell division

what happens with mutations in proto-oncogenes or tumor suppressors?

mutations in these genes cause abnormal and/or uncontrolled growth

what is an oncogene?

a proto-oncogene that has been changed to promote uncontrolled growth

how do oncoviruses arise?

directly from viral infection OR

when viral genome acts as an oncogene OR

when viral genome inserts into the host chromosome in such a way that it converts a proto-oncogene to an oncogene

how do oncolytic viruses work?

destroy the cancer cells directly by multiply within them and causing lysis;

others act indirectly by stimulating the host's cancer-fighting immune cells

what are inclusion bodies?

site of viral replication

what is syncytium?

fusing of cells into giant multinuclear cell

what human diseases are caused by prions?

Creutzfeldt-Jakob disease;

fatal familial insomnia;

kuru

what is the characteristic appearance of prions?

transmissible spongiform encephalopathies

what are coronaviridae?

a family of enveloped viruses derived from endomembrane system of the cell;

RNA virus consisting of a nucleocapsid of helical symmetry

what symptoms do coronaviruses cause?

mild to severe respiratory infections

which has the high affinity, SARS-CoV-2 or SARS-CoV? what does this mean?

SARS-CoV-2;

higher capacity to bind and cause infection more efficiently

what is indirect transmission of disease?

spread by fomites (money, doorknobs, etc)

what is the average incubation time?

5 days before symptoms appear

what is anosmia?

loss of sense of smell

what is the pathogenesis of coronavirus infections?

binds via spike proteins and enters cells in the respiratory tract;

once viruses enter cells, viral replication, assembly, and release leads to viral shedding down to the airways and alveolar epithelia cells in the lungs

what is a cytokine storm?

a severe immunological response associated with the release of too many cytokines too rapidly

what are monoclonal antibodies?

immunological proteins produced by B lymphocytes that may assist the body in overcoming the infectious agent

what is the Janssen COVID-19 vaccine?

viral vector vaccine containing the spike protein gene for SARS-CoV-2

what are microorganisms?

organisms that are too small to be seen with the unaided eye

what is microbiology?

study of microbes using various tools

types of microorganisms

bacteria;

archaea;

fungi;

protozoa;

algae;

viruses;

multicellular animal parasites;

what does pathogenic mean?

disease causing

what is the normal microbiota?

an enormous population of microorganisms that permanently colonizes the host

what roles do normal microbiota play?

prevent disease by competing with disease-causing microbes;

aid in digestion;

promote development of immune system;

may decrease allergies, asthma, etc;

may affect brain chemistry and weight

what is symbiosis?

the relationship between normal microbiota and the host

what is microbial antagonism?

a competition between microbes;

also called competitive exclusion

what are probiotics?

live microbes applied to or ingested into the body, intended to exert a beneficial effect

what is mutualism?

both organisms benefit

what is a communicable disease?

a disease that is spread from one host to another

what is a contagious disease?

a disease that is easily spread, highly communicable, from one host to another

what is a noncommunicable disease?

a disease that is not transmitted from one host to another

what are the three domans?

bacteria (prokaryotes), archaea (prokaryotes), eukarya (eukaryotes)

what do viroids consist of?

consist only of RNA; no protein coat

what are viroids?

obligate intracellular agents that use the machinery and nutrients of host cells to replicate

what do prions consist of?

consist only of protein; no DNA or RNA

what do viruses require?

require live organisms as hosts

what makes up a viral particle?

nucleic acid surrounded by a capsid (protein coat)

what is a nucelocapsid?

capsid plus nucleic acid

how do viral particles attach to host cells?

spikes attach to receptor sites on host cells;

phages attach by tail fibers

what is an enveloped virus?

surrounded by lipid bilayer obtained from host cell;

matrix protein between nucleocapsid and envelope

what is a non-enveloped virus?

AKA naked virus;

more resistant to disinfectants

what are helical viruses?

capsomeres arranged in a helix

what are complex viruses?

icosahedral nucleocapsid (head) with helical protein (tail);

example is phage

what are the key characteristics of viral taxonomy?

genome structure (nucleic acid and strandedness) and hosts infected;

others include viral shape, disease symptoms, etc

how are viruses classified?

classified based on features such as genome structure, host infected, shape, etc

what suffix do virus families end in?

-viridae

how do enveloped viruses enter a cell?

by fusion or endocytosis

what is synthesis?

the expression of viral genes to produce viral structural and catalytic genes;

synthesis of multiple copies of viral genome

how do RNA viruses replicate?

most replicases lack proofreading ability so mutations are generated during replication that results in an antigenic variation called antigenic drift;

mutations in surface proteins are not recognized by immune system

what is antigenic shift?

the process by which two or more different strains of a virus, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains.

what is assembly?

maturation;

involves packaging the nucleic acid into the capsid to form the nucleocapsid

how are enveloped viruses released?

via budding

how are non-enveloped viruses released?

when host cell dies, often by apoptosis initiated by the virus or host

what is release?

viral protein spikes insert into host cell membrane;

matrix proteins accumulate in the same area;

nucleocapsids are extruded;

covered with matrix protein and lipid envelope

what are persistent infections?

continue for years or lifetime;

may or may not have symptoms;

chronic or latent

what is a provirus?

the genetic material of a virus as incorporated into, and able to replicate with, the genome of a host cell

what are oncoviruses?

viruses that can cause cancer in humans

are most virus-induced tumors associated with DNA or RNA viruses?

DNA viruses

what viruses are associated with cancers in humans?

Epstein-Barr;

Hepatitis B;

Human herpesvirus type 8;

HPV;

Merkel cell polyomavirus;

Hepatitis C;

HTVL-1

what do oncolytic viruses do?

target and kill cancer cells

what is hemagglutination?

agglutination (clumping) of red blood cells

what are prions?

proteinaceous infectious agents

what are prions composed of?

composed solely of protein;

no nucleic acids

how do prions cause disease?

prion proteins accumulate in neural tissue;

neurons die and tissues develop holes, causing brain deterioration

what is a zoonotic disease?

a disease that can spread from animals to humans

what are the three known coronaviruses?

severe acute respiratory syndrome coronavirus SARS-CoV-1;

Middle East respiratory syndrome coronavirus MERS-CoV;

severe acute respiratory syndrome coronavirus-2 SARS-CoV-2

what are the symptoms of a lower respiratory tract (LRT) disease?

fever, cough, breathing difficulties, pneumonia;

may progress to acute respiratory distress syndrome, multiorgan failure, and death

what is the closest relative to SARS-CoV-2?

bat coronavirus detected in Rhinolophus affinis

what receptor does SARS-CoV-2 use?

angiotensin-converting enzyme 2 (human ACE2 (hACE2))