Large, brick shaped

Largest of all viruses

Virons contain one molecule of linear double-stranded DNA

Poxvirus

Small pearly or flesh-colored bumps

Contagious but not harmful

If pt has impaired immune system, then bumps can be extensive and disfiguring

-Molluscum contagiosum, Smallpox, cow pox, monkey pox, and orf

Leading cause of human viral disease, second only to infuenza and cold viruses.

Once a patient has become infected, they are infected for life

-Icosahedral symmetry

-Enveloped

-Single molecule of double stranded DNA

-Attracted to neurons

-Herpes

-By college 15% of the US population is infected and rises to about half by 35%

-spread in bodily secretions (sexually transmitted)

-Transplacental infection, Pregnant woman to a fetus

-most comon viral cause of congenital disease

-1 in 40 newborns in the U.S are infected

-CMV causes no symptoms in children and mild in adults

-CMV a major problem for those who are immunosuppressed

-Particularly important is CMV - retinitis in the eye which occurs in up to 15% of all AIDS patients

Poxvirus

Caused by variola virus

Variola major; more severe

Variola minor; less severe

Highly contagious, respiratory secretions and direct contact transmission

Fever, chills, nausea, severe muscle aches

Rash; flat lesions progress to papules (eruptive stage)

Papules to pustules that scab and scar

WHO started worldwide eradication in '67

Last endemic case reported in Somalia in '77

Considered eradicated in '80

Also known as human herpes virus-3

VZV causes 2 disease chicken-pox (usually in childhood)

Shingles later in life

-Varicella-zoster virus (herpes)

-Transmission via respiratory droplet

-Also spreat through direct contact with vesicles

-Extremely communicable, rates of infection exceeding 90% in suceptible households

-VZV spreads from the lungs by entering blood stream (viremia)

-VZV leaves the blood vessels and first infects sub-epithelial sites and then epithelial sites forming papulae, papulae becomes fluid filled vesicle

-Vesicles found on scalp (unique)

-Fluid filled vesicles become pustules, then scab

-The lesions itch, can cause bacterial superinfection

-recover in two weeks

-Major problems may be caused by infection in utero during the first trimester

Cow pox

Pox virus

Causes human disease via zoonosis

Transmission to humans via milking cows

Vaccinia virus is a mystery, not known whether a genetic recombo or derived from cowpox or from variola or living rep of extinct virus

Vaccinia was used for smallpox vaccination

Pox virus

Rare viral disease found mostly in the rain forest in West Africa

Named b/c was first discovered in lab monkeys in '58

Varicella Zoster Virus

Herpes

-Shingles is a recurrence of a latent varicella infection

-viruses move down nerves to epidermis

-Reactivation of virus due to stress, injury, disease

-Severe radicular pain in discrete arease, those innervated by the nerve in which latent infection has occurred

-Chicken pox-like lesions occur in restricted areas (dermatome) that are innervated by a single ganglion

DNA Virus

Pox virus

Contracted from sheep and goats

Non-enveloped

Double-stranded DNA

Capsid is icosahedral w/12 penton fibers that bind to r/c sites on host cell

Attacks mucoepithelial cells of conjunctiva, resp tract, gi and genitourinary tracts

Acute resp infection - common cold

Pharyngitis - resembles strep

Gastroenteritis

Epidemic keratoconjunctivitis

Diagnosis of chickenpox and shingles

live attenuated vaccine available which leads to antibody production and cell-mediated immunity

-chemotherapy includes: various nucleotide analogs

HSV-1 and HSV-2 first infect cells of the mucoepithlia or enter through wounds.  Then frequently set up latent infections in neuronal cells

-It is often noted that HSV-1 cuses infections above the waist and HSV-2 below the waist but this reflects the mode of transmission not ability of virus to cause disease

-Herpes labialis = fever blisters and cold sores on lips

-Eczema herpeticum = widespread cutaneous HSV in patients with pre-existing eczema

-Keratojunctivitis (herpetic keratitis) = infection of the cornea.... Leading cause of corneal blindness in industrialized nations

Genital Herpes

-Prodrome (early symptom, indicates onset of disease) 1-2 days of burning sensation in the area that is about to erupt

-Primary infection is characterized by viremia, fever, swollen lymph nodes, pain on urination

-Secondary episodes of genital herpes, which occur as a result of reactivation of virus are frequently less sever than the first episode

-Triggered by fever, menstruation, stress, UV light

-Whether there is an apparent active disease or not, and infected patient remains infectious without overt symptoms

Herpetic Whithlow

-herpes infection of fingers and hands

Herpes gladiatorum

-skin lesions cntracted by wrestlers spread by direct contact

Wart-causing

Papovaviridae

Naked dsDNA

Icosahedron capsid

Replicate in squamous epi of skin & mucous memb.

Diff serotypes cause diff types of warts

Common, Plantar, Laryngeal papillomas (benighn epi growths similar to warts on skin), and Genital

Infectious mononucleosis

African-Burkitts lymphoma

Nasopharyngeal cancer

Hairy oral leukoplakia

Papovaviridae

Human Papillomavirus

One of most common STI's in the world

~30 types of HPV spread through sexual contact

Single or multiple lesions appear in genital areas

Many infected have no symptoms

Cause neoplasms in humans and natural cancer in animals

Associated with (and very likely to cause) human penile, uterine, and cervical carcinomas

Herpes Virus

-infection with EBV occurs worldwide among humans and usually occurs as a subclinical infection in early childhood

-is acquired by contact with infected cervical and oral secretions

-infects and multiplies in the B cells in the oropharyngeal epithelium

-Most infections in young children are asymptomatic, symptoms are more pronounced in previously uninfected young adults

-T cells increase in number in the circulation and may account for up to 80% of the white blodd cells

-T cell response results in enlarged lymph glands, liver and spleen

-Activation of the T cells limits the proliferation of B cells and the disease resolves in 8-10 days

-tumor of the jaw and face found in children

-tumor cells show evidence of EBV DNA and tumor antigens and patients show a much higher level of anti-EBV antibodies than other members of the population

Herpes

-Tumor of the epithelium of the upper respiratory tract

-Tumor cells contain EBV DNA

-may be a genetic predisposition to the development of EBV cancers or there may be an environmental cofactor involved

-EBV- associated disease results in lesions in the mouth and has increased in frequency recently as it is an opportunistic infection of HIV-infected patients

-Herpes

Papovaviridae

Naked dsDNA viruses w/icosahedral symmetry

Natural hx of human polyomaviruses unknown, such as the method of their transmission

Primary plyomavirus infections have not been associated w/any specific clinical syndromes

Small, naked, icosahedral DNA viruses

Among most resistant viruses known

Infects cats, dogs, mice, and humans

Human parvovirus

Parvovirus B19 has been found in resp secretions of infected persons before the onset of rash, when they appear to have "just a cold"

Responsible for Fifth Disease

1st stage- 8 days after infect., fever & cold symp.

2nd stage- rash begins on face "slapped cheek" aka erythema infectiosum

Typically resolves in 1-2 weeks

Enveloped, negative strand RNA viruses

Helical symmetry

Includes Rubeola (measles) and mumps, parainfluenza

-formerly known as Kaposi's sarcoma associated herpes virus and is found in the saliva of many AIDS patients

-KS lesions are nodules or blotches that may be red, purple, brown, or black

-usually painless but sometimes painful and swollen

German measles

-Positive strand RNA virus

-Enveloped

-Icosahedral symetry

-Only member of the Rubrivirus genus of the Togavirus family

Paramyxovirus

Has hemagglutinin for attachment to host cell, lacks neuraminidase activity

Main route of infect. via inhalation of resp. secret.

Almost all infected pts show signs of disease

Highly contagious, esp 2-3 days before rash starts

-Togaviridae

-Transmitted by respiratory secretions

-initial site of infection is the upper respiratory tract. The virus replicates locally in the lymph nodes leading to viremia and spread to other tissues

-Rash (if it occurs) starts after an incubation period of approximately 2 weeks

-Risk to a fetus is highest in the first few weeks of pregnancy and then declines in terms of both frequency and severity, although there is still some risk in second trimester

-Virus infects the placenta and then spreads to the fetus

-If non-immune mothers are infected in the first trimester, up to 80% of neonates may have defects ( hearing loss, mental retardation, congenital heart defects, neurologic problems, ophthalmic problems, Congenital infections can infect others after birth for a year)

Rabies - Pasteur

Yellow- Fever by Walter Reed

RNA virus

Paramyxovirus

Rubeola virus

Fever

Resp tract sympt.- runny nose, cough

Conjunctivitis

Koplik's spots on muc memb- small (1-3mm), irregular, white spots, w/bluish halo

Maculopapular rash that extends from face to extremities

Paramyxovirus

Rubeola virus

Impaired cell-mediated immune response, there is continued growth of the virus in the lungs leading to giant cell pneumonia. Rare, often fatal

Otitis media and bacterial pneumonia common

1 in 1000 cases get encephalitis

Sub-acute sclerosing pan encephalitis- neuro disorder charact. by inflamm of the brain

-develops 1-10 years after initial infect. progressive, usually fatal. Those who survive are severely impaired mentally and physically

-very rare

1) Two primary types of symmetry of a capsid are?

2) viruses have different shapes, including........?

1) Helical or Icosahedral

2) spherical, bullet shaped, or filamentous

Only one serotype (antigenic type)

Provides life-long immunity

Attenuated live vaccine

-MMR

-Agents with no detectable nucleic acid

-appears to be self-replicating

- scientists believe that a relationship to viruses exist

Paramyxovirus

Four types, all can cause upper or lower resp infect., esp important in kids b/c respons for 40-50% of croup cases

Spongiform Encephalopathies..

Diseases cause holes in tissue, brain appears as a sponge. (mad-dow, kuru, scrapie, creutzfeldt-jacob)

Paramyxovirus

Causes swelling of salivary glands (parotids)

Transmission via resp secretions & saliva

Highly contagious

Infects upper/lower resp tract leading to local replication, virus spreads to lymph which leads to viremia

Complications- orchitis, and aseptic meningitis

Control- MMR vaccine, single serotype of mumps, life long immunity