Microbiology Chapters 6, 24, and 25

Animal virus multiplication

Adsorption: Binding of virus to specific molecule on host cell Penetration: Genome enters host cell Uncoating: The viral nucleic acid is released from capsid Synthesis: Viral components are produced Assembly: New viral particles are constructed Release: Assembled viruses are released by budding (exocytosis) or cell lysis

Flavivirus RNA

Dengue Fever

Satellite Virus

Dependent on other viruses for replication

Complications of chicken pox

Dysfunction of the brain due to pressure build up as a result of fat accumulation; usually caused by using aspirin to reduce fever.

Lytic Cycle

Ends with lysis and death of host cell

Ryes Syndrome

Enlargement of liver and brain Effects children and teenagers (Usually) Aspirin is lined to causing the syndrome Signs/symptoms include: Confusion, seizures, loss of consciousness

Budding

Exocytosis; nucleocapsid binds to membrane which pinches off and sheds viruses gradually. Cell is not immediately destroyed

Small Pox

Exposure through inhalation or skin contact Symptoms include fever, malaise, exhaustion, and rash Treated with vaccination Caused by poxvirus dsDNA virus

HSV- Recurrent infection can be triggered by what ?

Fever, UV radiation, Stress, & Mechanical injury

Herpes Labialis

HSV-1 Fever blisters & cold sores Most common recurrent HSV-1

Herpetic gingivostomatitis

HSV-1 Infection of oropharynx in young children, fever, sore throat, swollen lymph nodes

Herpetic Keratitis

HSV-1 Ocular herpes

Herpes virus

HSV-1 (herpes simplex 1) HSV-2 (Herpes simplex 2) VZV- Varicella zoster virus EBV- Epstein- barr virus

Helical example

Hebola virus

Viroids

Infectious RNA that cause some diseases only found in plants. No protein coat.

Hepatitis

Inflammatory disease of liver cells that may result from several viruses

Orthomyxovirus- RNA

Influenza

What is a Virus?

Intracellular obligatory parasite, contains RNA or DNA

Course of viral disease

Invasion at portal entry and primary infection; Some viruses replicate locally, others enter the circulation and infect other tissues

Poxvirus Structure

Largest and most complex animal virus Largest genome of all viruses dsDNA Virus Multiply in cytoplasm Specificity for cytoplasm of epidermal cells and subcutaneous connective tissue (skin)

HSV-2

Lesions on genitalia, possibly oral also Can be spread without visible lesions Enters lumbosacral spinal nerve trunk ganglia

helical virus

Long rods, Capsids are hollow cylinders and spirally arranged

General structure of a virus

Nucleic acid- Can be ss or ds; both RNA and DNA Protein coat; capsid Individual subunits of capsid; Capsomere Envelope- Covers the capsid, made up of lipid, protein, and carbohydrate; enveloped or non enveloped. May have spikes; project from surface of envelope that are responsible for clumping of RBC

Shingles- Herpes Zoster

Occurs mainly in adults Usually a result of chicken pox in past & Varicella-zoster virus Vesicular rash along subcutaneous sensory nerves Treated with acyclovir , Vaccines available

Coronaviridae

RNA Virus Genus- Coronavirus Common Name- Sars Virus Disease- Severe Acute Respiratory Syndrome

Flaviviradae

RNA Virus Genus- Flavivirus Common Name- Dengue fever virus Disease- Dengue fever

Retroviridae

RNA Virus Genus- Lenitrivirus Common Name- HIV Disease- HIV

Rhabdoviridae

RNA Virus Genus- Lyssavirus Common Name- Rabies Disease- Rabies

Reoviridae

RNA Virus Genus- Rotavirus Common name- Colorado tick virus Disease- Colorado tick virus, Rotavirus gastroenteritis

Hepatitis C

RNA Virus - Enveloped Transmitted through blood or intimate contact Incubation is 2-8 weeks Symptoms include fever, rash, arthritis Jaundice is common Onset/duration: acute to chronic Complications: Cirrhosis, chronic inflammation, cancer No vaccine available

Hepatitis A

RNA virus- non-enveloped Transmitted through oral-fecal; water or food borne Incubation is 2-7 weeks Symptoms include fever and GI tract disorders Jaundice 1 in 10 Onset/duration: Acute/Short Vaccination available

Rhabdovirus RNA

Rabies

Common Symptoms of a viral infection

Rashes Fever Muscle aches Respiratory involvement Swollen lymph nodes

Reovirus

Rotavirus; diarrhea

Togavirus RNA

Rubella

Coronavirus RNA

Severe acute respiratory syndrome

Mononucleosis

Symptoms include: Fever, fatigue, sore throat, swollen lymph nodes. Caused by epstein-barr virus Transmitted through close contact or intimate contact and saliva.

Chicken Pox

Transmitted through respiratory route and direct contact with fluid from a chicken pox rash Infection is localized in skin; Vesicular rash forms Usually develops lifetime immunity Caused by Varicella Virus ds DNA virus Symptoms include Rash, mild headache and fever, malaise

Positive sense RNA

ssRNA genomes ready for immediate translation

Negative sense RNA

ssRNA genomes that must be converted into proper form for translation

Complex Virus

Capsid has a tail

Retrovirus RNA

AIDS

How to treat HSV ?

Acyclovir, famciclovir, valacyclovir; topical medications

Satellite viruses

Adeno associated virus- Replicates only in cells infected with adenovirus Delta agent- Naked strand RNA expressed only in presence of hepatitis B virus.

Polyhedral example

Adeno virus

Examples of Non-Enveloped Viruses

Adenovirus- dsDNA Parvovirus- ssDNA Papovavirus- dsDNA Picornevirus- ssRNA Reovirus- dsDNA

Viral components of a virus

Capsids, nucleic acids, and envelopes

Orthromyxoviridae

RNA Virus Genus- Influenza Common Name- Type A Influenza Disease- Influenza- Flu

Six steps in Phage Replication

Adsorption: Binding of virus to specific molecule on host cell Penetration: Genome enters host cell Replication: Viral components produced Assembly: Viral components assembled Maturation: Completion of viral formation Release: Viruses leave cell to infect other cells

Enveloped virus

Capsid covered by an envelope

Measles- Rubeola

Caused by Family: Paramyxoviradae, Genus Morbillivirus - Enveloped Also known as red measles and rubeola VERY Contagious Transmitted by respiratory aerosols Symptoms 8-12 days following include: Sore throat, dry cough, headache, fever, koplick spots (oral lesions) MMR vaccine as prevention

German measles - Rubella

Caused by Rubivirus RNA virus Transmitted through respiratory route Also called 3 day measles - rashes lasts up to 3 days MMR vaccine Maternal infection can lead to still birth, heart and mental retardation in newborns in first trimester No koplik spots

Spongiform encephalopathies

Caused by prions, extremely resistant to usual sterilization techniques

Mumps- Rubula

Caused by rubula virus- Family Paramyxoviradae RNA virus Infection of parotid gland Fever and pain while swallowing Transmitted through respiratory tract Virus is found in blood, saliva, and urine MMR Vaccine

Damage to Host Cell

Changes in size and shape, alter DNA, Cell lysis, Cells fuse to form multinucleated cells, Inclusion bodies.

Body defenses against viral infections

Combines action of interferon, antibodies, and cytotoxic T Cells

Three types of warts

Common seed warts: Painless, elevated rough growth Plantar warts: Deep, painful, on bottom of feet Genital warts: Most common STD, tiny, flat, extensive branching and cauliflower like masses

Papovariridae

DNA Virus Genus- Polyomavirus Common Name- JC Virus Disease- Progressive multi-focal leukcencephalopathy

Herpesviridae

DNA Virus Genus- Simplex virus Common Name- Herpes Simplex 1 & Herpes simplex 2 Disease- Fever blister, Shingles, Genital herpes

Hepadnaviridae

DNA Virus Genus- Hepadnavirus Common name- Hepatitis B Virus Disease- Serum Hepatitis

Adenoviridae

DNA Virus Genus- Mastadenovirus Common Name- Human Adenoviruses Disease- Adenovirus infection

Poxviridae

DNA Virus Genus- Orthopoxvirus Common Name- Varida and Vaccinia Disease- Small pox and cow pox

Hepatitis B

DNA Virus- Enveloped Transmitted through blood or sexual contact Incubation is 1-6 months Symptoms include fever, rash, arthritis Jaundice is common Onset/duration: Gradual, chronic Complications: hepatic cancer, cirrhosis, chronic active hepatitis, low white blood cell count, enlarged liver. Vaccination available

Paramyxoviridae

RNA Virus Genus- Paramyxovirus Common Name- Mumps Disease- Mumps

Togaviridae

RNA Virus Genus- Aphlavirus & Rubivirus Disease- Rubella

Diseases caused by Prions

Madcow disease Creutzfeldt- Jakob disease: Degeneration of brain tissue

Polyhedral Virus

Many sided

Paramyxovirus RNA

Measles & Mumps

Prions

Misfolded proteins, contain no nucleic acid

Lysis

Nonenveloped and complex viruses released when cell dies and ruptures

Warts are caused by what virus ?

Papilloma virus- Double stranded DNA Virus (Non-enveloped)

Examples of Enveloped Viruses

Paramyxovirus- ssRNA Rhabdovirus Orthomyxovirus Herpes virus Poxvirus- dsDNA Togavirus Retrovirus Coronavirus

Lysogeny

Phage DNA is incorporated into host without lysis

Picornavirus RNA

Polio & Hepatitis A

Warts

Proliferation of skin cells to produce growth called papilloma Spread by contact Can be removed by chemical application of podophyllin or physical removal by cauterization, freezing, or laser Prevention: Gardasil vaccination

Function of capsid/Envelope

Protects nucleic acid when virus is outside of host Helps the virus bind to a cell surface and assists with penetration

Picornaviradae

RNA Virus Genus- Enterovirus Common name- Poliovirus, hepatitis A, human rhinovirus Disease- Poliomyeltis, hand- foot - mouth disease, short term hepatitis, common cold bronchitis.

Burkitts Lymphoma

Tumor of large B lymphocytes Caused by Epstein-barr virus Occurs in patients with low immunity usually from AIDS or malaria Treated with IV Gamma globulin, interferon, acyclovir, and monoclonal antibodies

DNA Viruses

Usually double stranded but may be single stranded, DNA viruses are budded off the nucleus

HSV-1

Usually lesions on the oropharnyx; cold sores, fever blisters Enters 5th Cranial nerve

RNA Viruses

Usually single, may be double stranded; RNA viruses multiply in and are released from the cytoplasm

Complications from small pox

Variola Major: Highly virulent, caused toxemia, shock, and intravascular cuagulation (Clots) Variola Minor: Less Virulent

Cytopathic Effects

Virus- induced damage to cell

What factors determine a host for a virus?

Viruses requirements for specific attachment Availability of cellular factor for multiplication Ex. Hep B needs human liver cells Poliovirus needs primate intestinal and nerve cells Rabies needs various cells of many mammals

Bacteriophage

Viruses that infect bacteria

Plaque

Visible, clear, well defined in monolayer of virus infected cells in a culture