Chapter 25- Pathogenic RNA Viruses Flashcards

Question

What are the most common modes of tranmission of HIV?

Answer 1

Females- high risk heterosexual contact followed by intravenous drug use Males- homosexual contact followed by intravenous drug use

Answer 2

Patient has one or more rare disease, antibodies against HIV, fewer than 200 CD4 lymphocytes per microliter of blood, unexplained weight loss, fatigue Serological diagnosis- test for antibodies through ELISA, Western blot, agglutination, PCR gives definitive answer Signs and symptoms vary according to the disease present Long term non-progressors appear not to develop AIDS- may be due to defective virions or lack of effective coreceptors of virus

Answer 3

HAART (highly active antiretroviral therapy)- used to reduce viral replication Cocktail of antiviral drugs including nucleoside analogs, protease inhibitors, reverse transcriptase inhibitors Various problems must be overcome to develop a vaccine

Answer 4

Behavioral changes can slow progression of AIDS epidemic Abstinence and safe sex Use of clean needles Screening of blood products Administer AZT to infected pregnant women

Answer 5

Enveloped, unsegemnted, -ssRNA Causes cells to fuse and form giant, multinucleate syncytia, syncytia enable virus to evade immune system 4 Genera infect humans: Morbillivirus (measles virus) Paramyxovirus- causes croup Rubulavirus (mumps virus) Pneumovirus (respiratory syncytia virus)

Answer 6

1 of 5 clasical childhood diseases caused by paramyxovirus Spread in the air via respiratory droplets Viruses infect the respiratory tract and spread throughout the body Koplik's spots appear on mucous membrane of the mouth Lesions then appear on the head and spread over body Rare complications- pneumonia, encephalities, and subacutre sclerosing panencephalitis (SSPE)

Answer 7

Signs of measles, particuarly Koplik's spots, are diagnostic No antiviral treatment available Vaccine (MMR) has eliminated endemic measles in USA Measles remain a frequent cause of death in other countries

Answer 8

Causative agent: Mumps virus, paramyxovirus Transmission occurs via respiratory secretions Viruses infect respiratory system and spreads to other organs Results in parotitis- painful enlargement of the parotid salivary glands Infections are often asymptomatic No specific treatment is available Vacccine has almost eradicated mumps in industrialized world

Answer 9

Enveloped, unsegmented, -ssRNA virus Rabies virus - a rhabdovirus (bullet-shaped) Classic zoonotic disease of animals Primary reservoir of urban areas is a dog, bats are the source of most cases of rabies in humans Transmission occurs via a bite- virus sometimes introduced through break in skin or inhalation Virus attaches to nerve cells and travels to CNS - results in rabies specific neurological symptoms (hydrophobia, seizures, hallucinations, paralysis, and death) Death results from respiratory paralysis and other complications

Answer 10

Diagnosis- neurological symptoms, characteristic negri bodies in the brain Treatment- too late to intervene by the time symptoms and antibodies occur, treat at site of infection with injection of human rabies immune globulin, vaccination with human diploid cell vaccine at days 0,3,7, and 14 Prevention- vaccination of domestic cats and dogs

Answer 11

Disease is limited to respiratory tract Transmission occurs via fomites, hands, and respiratory droplets Virus causes formation of syncytia in lungs Result in difficult breathing known as dyspnea Leading cause of fatal respiratory disease in infants and children Infection is asymptomatic or a mild cold in older children and adults Diagnosis based on signs of respiratory distresss - verified by immunoassay Treatment is supportive

Answer 12

Hemorraghic fevers- caused by Marburg Virus and Ebola Virus Found in Germany, Zimbabwe, Kenya, Uganda, Angola, etc. Natural reservoir and mode of transmission to humans unknown Spread person to person by contaminated body fluids and syringes Virions attack many cells of the body, especially the macrophages and liver cells Uncontrolled bleeding under the skin from every body opening due to jelly like consistency of organs (viral glycoprotein prevents the neighboring cells from adhering- allows blood to leak out of vessels) Only treatment is fluid replacemtn 90% of human victims die

Answer 13

Influenza- Orthomyxovirus Type A and B Infection occurs primarily through inhalation of airborne viruses Rarely attack cells outside the lungs Death of infected epithelial cells eliminates the lungs epithelial linings Patients more susceptible to secondary bacterial infections Symptoms include fever, malaise, headache, and myalgia Induced by cytokines released as part of immune response

Answer 14

Genome consists of 8 different -ssRNA molecules Envelope components- highly variable with respect to glycoprotein spikes, contains: Hemagglutinin- entry, attachment to pulmonary epithelial cells or trigger endocytosis Neuraminadase- exit, provide virus access to cell surfaces by hydrolyzing mucus

Answer 15

Mutations result in production of new strains of influenza Antigenic drift- minor variations Antigenic shift- major antigenic changes

Answer 16

Diagnosis- signs and symptoms, community wide outbreak Treatment- drugs prevent viral uncoating or block virion release from infected cells Oseltamivir pills or inhaled zanamivir mist are neuramindase inhibitors, must be administered within 48h of infection Prevention- multi valent vaccine

Answer 17

Arenavirus- Hepatitis D is caused by Hepatitis D virus Transmitted through bodily fluids via sexual contact and contaminated needles Hepatitis D requires Hepatitis B to be virulent- cannot attach to liver cells Hepatitis D plays a role in triggering liver cancer Vaccination against Hepatitis B limits Hepatitis D

Answer 18

Only microbes with genomes composed of dsRNA Originally considered respiratory enteric orphans (REO) Not initially associated with any diseases Includes Rotavirus- most common cause of infantile gastroenteritis, unique wheel-like appearance, significant cause of death in developing countries