Microbio Test 3 (Viruses, H. pylori, C. difficile)

Reasons for study viruses?

major cause of disease, new source of therapy, new viruses emerging, aquuatic world, generic variation

What is a complete virus particle called?

virion

What does virion consist of?

greater than one molecule of DNA/RNA enclosed in coat of proteins

Can virion reproduce independent of living cell?

no, nor can it carry out cell division

What types of bacteria can viruses infect?

bacteriophages, archaeal viruses, eukaryotic (plants, animals, protists, fungi)

What type of microscope has to be used to view viruses?

electron microscope

What structure on the viruse is composed of nucleic acid and a protein coat?

nucleocapsid

What is a large macromolecular structure which serves as a protein coat of a virus called?

capsid

What are the protein subunits in capsids called?

protomers

What are the three shapes capsids can be?

helical, icosahedral, or complex

What are characteristics of helical capsids?

shaped like hollow tube, protomers self assemble, size of capsid is a function of nucleic acid

What are characteristics of icosahedral capsids?

polyhedron shape, nature's favorite shape, capsomers

What are characteristics of complex capsids?

viruses that don't fit in helical or icosahedral capsids

Many viruses are bound by an outer, flexible, membranous layer called _________

envelope

Where do animal virus envelopes arise from?

the host cell plasma or nuclear membranes

Viral encoded ___________ _______ may project from the envelope surface as spikes or peplomers

envelope proteins

What are envelope proteins involved in?

viral attachment to host cell, identifiction of virus, enzymatic or other activity, nucleic acid replication

Do virions have enzymes?

yes some do

What can have a single or double stranded DNA or RNA?

viral genome

What does viral multiplication depend on?

viral structure and genome

Specific receptor attachment determines ______ __________

host preference

What are the three methods of viral entry and uncoating?

fusion of the viral envelope w host membrane (nucleocapsid enters), endocytosis in vesicle (endosome aids in viral uncoating), injection of nucleic acid

What dictates the events in the synthesis stage?

genome

What proteins are important in assembly?

late proteins

Where does assembly take place?

bacteriophages in stages, some in nucleus, some in cytoplasm

What do nonenveloped viruses do?

lyse the host cell

What do enveloped viruses do?

budding, nucleocapsid binds to viral proteins, envelop derived for host cell membrane

What viral infection multiplies immediately upon entry and lyses bacterial host cell?

virulent phage

What viral infection reproduces lytically and remain within host cell without destroying it?

temperate phages

What do lysogens do?

infect bacterial host and can switch from lysogenic to lytic cycle

What happens in lysogenic conversion?

temeprate phage change phenotype of its host

What are two advantages to lysogeny for virus?

phage remains viable but may not replicate, multiplicity of infection ensures survival of host cell

What is the result of lysogenic conversion?

lyse and release of phage particles- occurs from process of induction

What infection do we find in eukaryotic cells?

cytocidal infection which results in cell death through lysis

What are some cytopathic effects in eukaryotic cells? (CPEs)

degenerative changes, abnormalities- transformation to malignant cell

What is a tumor?

growth or lump of tissue

Tumors that remain in place are called

benign

What is neoplasia?

abnormal new cell growth and reproduction due to loss of regulation

What is anaplasia?

reversion to a more primitive or less differentiated state

What is metastasis?

spread of cancerous cells throughout body

what is carcinogenesis?

multistep process of viruses causing cancer

What are oncogenes?

cancer causing genes

Where do oncogenes come from?

the virus or proto-oncogenes

What are the three possible mechanisms by which viruses cause cancer?

viral proteins bind host cell tumor suppressor proteins, carry oncogene into cell and insert it into host genome, insertion of promoter or enhancer next to cellular oncogene

What family does HPV belong to?

papillomavirus family

What is the structure of HPV?

nonenveloped icosehedral capsid, double-stranded, supercoiled, circular DNA genome

How many know viruses of HPV are there?

over 120

What does HPV infect?

keratinocytes of skin or mucous membrane

How is HPV most commonly transmitted disease?

sexually

What are symptoms of HPV?

warts- plantar, verrucae, flat or plane, anogenital codylomata

What type of cancers can HPV cause?

16,19,31,45, cervical (most common), degrade p53

How is non-sexual HPV transmitted?

virus attacks through direct contact (cuts or abrasions), autoinoculation (infected skin touching non-infected, infected walking surfaces), prenatal (mother to child during birth- respiratory papillomatosis, warts in larynx)

How is HPV sexually transmitted?

sexual activity, hands and genitals, shared objects

What are ways to prevent HPV?

abstinence, protection (condoms), vaccination (gardisil and cervavix), microbicides

Where did HIV originate?

western Africa in early twentieth century

When was HIV recognized by CDC?

1981

What virus is responsible for 30 million deaths?

HIV

What is AIDS caused by?

human immunodeficiency virus (HIV)

What family is HIV in?

RNA virus family Retroviridae

What caused the great pandemic in second half twentieth century?

AIDS

What are the three theories of origin of disease?

HIV-1 evolved from chimp virus SIVcpz, only group M HIV-1 is widespread in U.S., HIV-2 is widespread in Africa

What are some ways HIV can be transmitted?

infected-blood, semen, vaginal secretions comes in contact with broken skin or mucous; mother to child; contaminated sharps/needles

What are ways HIV can't get transmitted?

urine, coughing, sharing utensils, tears, saliva, sweat, casual contact

What is the HIV life cycle?

attachment to CD2 cells (T helper cells), entry, RNA-DNA (reverse transcriptase), integration into human genome as provirus

What famous person in the band "Queen" died of AIDS?

Freddie Mercury

What famous basketball player had HIV?

Magic Johnson, 1991

Who was expelled from school because he was infected with HIV?

Ryan White

Can the HIV remain latent-asymptomatic?

yes

Can HIV direct synthesis of viral RNA to synthesis of new viral particles?

yes

In HIV life cycle, how are new virion assembled and released?

budding and lysis

How long do patients live that rapidly develop clinical AIDS?

2-3 years

In the majority of patients, how long does it take the HIV infection to progress to AIDS?

8-10 years

What does AIDS compromise?

the immune systems ability to defend against the virus

What is the definition of AIDS?

immune system no longer able to defend against virus (All HIV-infected individuals who have fewer than 200 CD4+ T cells/microliter of blood or CD4+ cell percentage of lymphocytes of less than 14)

What are methods of diagnosis HIV?

viral isolation and culture, PCR-genome analysis, detect reverse transcriptase activity or viral antigens, detect anti-HIV antibodies in the blood

What detection suggests HIV diagnoses?

reverse transcriptase activity or viral antigens (foreign substance that induces an immune response), anti-HIV antibodies in the blood

What treatments are there for AIDS?

drugs with protease and integrase inhibitors and nucleoside reverse transcriptase inhibitors, reducing viral load, disease symptoms, and treating disease and malignancies

Is there a cure for AIDS?

no

What are ways to prevent AIDS?

barrier protection, not sharing intravenous needles or syringes, blood screening

Is there a vaccine for AIDS?

no

What is a problem with developing a vaccine for AIDS?

envelope proteins of virus continually change their antigenic properties

What type of bacterium is Clostridium difficile and what shape?

gram positive, rod

Is C. difficile spore forming?

yes

Is C. difficile aerobic or anaerobic?

anaerobe

Where is C. difficile found?

gut

______ _____________ is associated with healthcare infections.

C. difficile

C. difficile is associated with 14,000 deaths a year in the US due to what factors?

antibiotic therapy, advanced age, immunocompromised, long stay in health care facilities, gastrointestinal surgery

How is C. difficile transmitted?

fecal-oral route, vie hands of healthcare personnel

What are methods of detecting C. difficile?

stool culture, test for gene encoding for toxin, antigenic testing, detection of toxin at room temperature

What are treatment methods for C. difficile?

antibiotics for 10 days, fecal transplant to re-establish normal flora

What type of bacterium is Helicobacter pylori and what shape?

gram negative, curved rod

Does H. pylori exhibit urease activity?

yes

Where is H. pylori found?

stomach

What time period of life does H. pylori usually infect?

childhood

What percent of individuals with H.pylori are asymptomatic?

80%

What are symptoms of H. pylori?

burning pain in abdomen, nausea, loss appetite, frequent burping, bloating, unintentional weight loss

What are ways of transmission H. pylori?

person to person through saliva, vomit or fecal matter, contaminated food or water

Ways to diagnose H. pylori?

blood test, breath test, stool test, scope test

What are treatments of H. pylori?

proton pump inhibitors (stop acid production), histamine blocker, bismuth subsalicylate