RNA Viruses

RNA Viruses Rotavirus (reovirus) – “A Race on the Rio”  Naked segmented dsRNA virus  Transmission via fecal-oral route – common to daycares and kindergarten, especially in the winter months  Disease includes watery diarrhea and gastroenteritis – #1 cause of infant gastritis  Treatment via oral rehydration therapy and live attenuated vaccine – vaccine may induce intussusception (ileum to cecum) due enlarged Peyer’s patches  Other comments o Virulence factor is the NSP4 enterotoxin, which increases chloride permeability o Wheel-shaped appearance under the microscope Poliovirus (picornavirus – enterovirus) – “Flamingo Breeding Pool”  Naked (+) ssRNA virus  Transmission via fecal-oral route  Disease includes poliomyelitis (flaccid asymmetric paralysis, decreased DTRs and respiratory insufÏciency, muscle atrophy, and aseptic meningitis)  Treatment via Salk (IgG) vaccine or Sabin (IgM and IgG) – the latter confers group immunity with person-to-person contact  Other comments o Virus targets the anterior horn of the spinal cord and replicates in the tonsils and ileal Peyer’s patches every two to three weeks Coxsackievirus (picornavirus – enterovirus) – “Coxsackie Cockatoos”  Naked (+) ssRNA virus  Transmission via fecal-oral route – most common during summer months  Disease includes: o A is characterized as “hand, foot, and mouth” disease (red vesicular rashes and sores, respectively), aseptic meningitis, pharyngitis, and the common cold o B is characterized by Bornholm’s disease (cold and flu-like symptoms, sharp chest pain with difÏculty breathing, aseptic meningitis, and myocarditis)  Other comments o Coxsackie B can progress to a systemic life-threatening disease Rhinovirus (picornavirus – enterovirus) – “Rhino Petting Zoo”  Naked (+) ssRNA virus  Transmission via respiratory droplets, saliva, and fomites  Disease includes the upper respiratory infection – #1 cause of common cold  Other comments o There are >100 serotypes, therefore no form of treatment exists o Virus grows best at 33ºC therefore inhabits the upper respiratory tract o Virus enters the host cell via attachment to ICAM-1 Hepatitis A (picornavirus) – “Hungry Hungry Hep A Hippo”  Naked (+) ssRNA virus  Transmission via fecal-oral route – contaminated water and shellfish; common to travelers to endemic areas  Disease includes jaundice, vomiting, nausea, abdominal pain, arthralgia, and aversion to smoking tobacco products – symptoms last approximately one month  Treatment via inactivated vaccine; prophylaxis via water purification  Other comments o Anti-HAV IgG is derived from a prior infection or vaccination o Children will display anicteric HAV infection (lack of jaundice) o Infected individuals are not carriers as HAV is self-limiting Echovirus (picornavirus – enterovirus)  Naked (+) ssRNA virus  Transmission via fecal-oral route – common to infants and young children  Disease includes fever and cold-like symptoms that progress to a rash and/or aseptic meningitis  Other comments o Disease can progress to systemic disease including myocarditis and liver failure (similar to Coxsackie B) Norovirus (calicivirus) – “Cali Sea Cruise”  Naked (+) ssRNA virus  Transmission via fecal-oral route – contaminated shell fish; common to cruises, post-hurricane, day-care centers, and Olympics (2018)  Disease includes nausea, vomiting, and watery stools – #1 cause of viral gastroenteritis  Other comments o Virus functions to produce one long polyprotein that is broken down into its functional subunits via proteases Hepatitis E virus (hepesvirus)  Naked (+) ssRNA virus   Transmission via fecal-oral route Disease is similar to that of Hepatitis A Hepatitis C virus (flavivirus) – “The Hep Sea”  Enveloped icosahedral (+) ssRNA virus  Transmission via infected blood and rarely sexual intercourse  Disease includes jaundice and hepatitis – 80% of infections become chronic and progress to hepatocellular carcinoma or cirrhosis – #1 cause of liver transplants  Treatment via IFN- and ribavirin  Other comments o Anti-HCV antibodies will appear 6-8 weeks post-infection o Virus has high antigenic variation of envelope proteins due to the poor proofreading via lack of 3’-5’ exonuclease activity Dengue virus (flavivirus – arbovirus)  Enveloped (+) ssRNA virus  Transmission via Aedes egyptei mosquito  Disease includes break bone fever (first infection) and hemorrhagic shock (second infection) Yellow fever (flavivirus – arbovirus)  Enveloped (+) ssRNA virus  Transmission via Aedes egyptei mosquito – primarily in W. Africa and S. America  Disease includes high fever, black vomit, back ache, and jaundice  Treatment via live attenuated vaccine St. Louis Encephalitis (flavivirus – arbovirus)  Enveloped (+) ssRNA virus  Transmission via Aedes egyptei mosquito  Disease includes fever and encephalitis West Nile Virus (flavivirus – arbovirus)  Enveloped (+) ssRNA virus  Transmission via mosquito – reservoir is birds  Disease includes encephalitis, fever, meningitis, and myelitis that can progress to flaccid paralysis Zika    Virus (flavivirus – arbovirus) Enveloped (+) ssRNA virus Transmission primarily via mosquito, but sexual and vertical transmission are also possible Disease includes fever, rash, conjunctivitis, muscle and joint pain, malaise, and headache lasting 2-7 days; also, congenital microcephaly or miscarriage Reubella (togavirus) – “Toga-toga-togavirus!”  Enveloped (+) ssRNA virus  Transmission via respiratory droplets, saliva, human-to-human contact, and vertically – common in unvaccinated immigrant children  Disease includes: o Congenital is characterized as jaundice, cataracts, sensory-neural deafness, and patent ductus arteriosus o Childhood is characterized as lymphadenopathy, fever, and maculopapular rash that begins on the face and spreads to the trunk and extremities (lasting three days)  Treatment via MMR vaccine  Other comments o This disease is also referred to as German measles Coronavirus – “Kingdom of SARS”  Enveloped (+) ssRNA virus  Transmission via respiratory droplets, saliva, and human-to-human contact  Disease includes common cold, Middle East Respiratory Syndrome (MERS), and Severe Acute Respiratory Syndrome (SARS) – atypical pneumonia; #2 cause of common cold Human T-cell Leukemia virus (HTLV-1) (retrovirus)  This is a cause of human T-cell leukemia, which has been linked to a paralytic disease (tropical spastic paraparesis) that is common to the Caribbean. Human immunodeficiency virus (HIV) (retrovirus) – “One Cane to Rule Them All”  Enveloped (+) diploid ssRNA virus  Transmission via sexual intercourse, vertically, or blood  Disease includes flu and mono-like symptoms with lymphadenopathy and wasting syndrome  Treatment via HAART  Other comments o o o o o Env – codes for gp41 and gp120 are transmembrane and glycoproteins, resp. and aid in attachment and fusion of HIV to target cell Gag – codes for capsid and matrix proteins (p24) Pol – codes for reverse transcriptase, protease, and integrase Viruses attaches and fuses to host cell via CD4, CCR5, and CXCR4 receptors, resulting in the formation of multinucleated giant T-cells AIDS defining illnesses – Candida, Pneumocystis, Kaposi sarcoma, Histoplasmosis, JC virus, CMV, EBV, Cryptosporidium, Mycobacterium avium, and Toxoplasmosis Orthomyxovirus –  Enveloped (-) segmented ssRNA w/ RNA-dependent RNA polymerase  Transmission via respiratory droplets  Disease includes the flu  Treatment via seasonal vaccines  Other comments o Virulence factors include hemagglutinin (HA) and neuraminidase (NA), which are responsible for (1) binding of sialic acid allowing for adherence to respiratory epithelium and (2) cleavage of neuraminic acid, which disrupts the mucin barrier, respectively. o Endemics occur via genetic shift and antigenic drift involving random point mutations of HA and NA, meanwhile pandemics occur when different viruses infect the same cell and exchange segmented RNAs to produce an entirely new strain. Measles (rubeola) (paramyxovirus) –  Enveloped (-) ssRNA w/ RNA-dependent RNA polymerase  Transmission via respiratory droplets, saliva, and human-to-human contact  Disease includes fever, cough, kolpik spots (bright red spots w/ blue center) in the mouth, maculopapular rash beginning at the head and spreading downwards, and subacute sclerosing panencephalitis (SSPE)  Treatment via MMR vaccine Mumps (paramyxovirus) –  Enveloped (-) ssRNA w/ RNA-dependent RNA polymerase  Transmission via respiratory droplets, saliva, and human-to-human contact  Disease includes infection of parotid gland and testis (orchitis); aseptic meningitis and pancreatitis may also occur  Treatment via MMR vaccine  Other comments o Male who are infected will often become sterile due to testicular infection Parainfluenza (paramyxovirus) –  Enveloped (-) ssRNA w/ RNA-dependent RNA polymerase  Transmission via respiratory droplets, saliva, and human-to-human contact  Disease includes cold-like symptoms or a more severe respiratory disease (croup, characterized by seal-like barking caused by a swollen larynx) Respiratory syncytial virus (RSV) (paramyxovirus)  Enveloped (-) ssRNA w/ RNA-dependent RNA polymerase  Transmission via respiratory droplets, saliva, and human-to-human contact – highly contagious, esp. in the winter and spring  Disease includes viral pneumonia and otitis media – #1 cause in infants <6 mo. Rabies (rhabdovirus)  Enveloped (-) ssRNA w/ RNA-dependent RNA polymerase  Transmission via animal bites, esp. bats, raccoons, and dogs  Disease includes a progressive neurological disease characterized by fever, malaise, photophobia, agitation, hydrophobia, paralysis, coma, and death  Treatment via immediate passive immunization  Other comments o Bullet-shaped virus o Virus replicates in the salivary glands, thus produces hypersalivation or foaming at the mouth o Negri bodies in the cerebellum and hippocampus are present and confirm infection during autopsies Ebola virus (filovirus)  Enveloped (-) ssRNA w/ RNA-dependent RNA polymerase  Transmission via direct contact with blood and secretions or dead bodies  Disease includes hemorrhagic fever, flu-like symptoms, diarrhea and vomiting, myalgia – all of which can progress to DIC  Other comments o Virus infects monocytes, macrophages, dendritic cells, hepatocytes, and endothelial cells – can incubate <21 days o o Infected individuals must undergo Level 1 isolation and supportive care Suspected infected or close-contact individuals must undergo quarantine Lymphocyte choriomeningitis virus (LCMV) (arenavirus)  Enveloped (-) ssRNA w/ RNA-dependent RNA polymerase  Transmission via infected rodents and vertically  Disease includes flu-like illness, potential viral meningitis, miscarriage or stillbirths  Other comments o Diagnose via virus-specific antibodies Lassa fever encephalitis (arenavirus)  Enveloped (-) ssRNA w/ RNA-dependent RNA polymerase  Transmission via infected rodents - endemic to W. Africa  Disease includes fever, sore throat, abdominal pain, vomiting, and hypotension – fatal in 50% of cases  Other comments o Diagnose via virus-specific antibodies California encephalitis (bunyavirus)  Enveloped (-) ssRNA w/ RNA-dependent RNA polymerase  Transmission via arthropod vectors  Disease includes fever and encephalitis Hantavirus (bunyavirus)  Enveloped (-) ssRNA w/ RNA-dependent RNA polymerase  Transmission via rodent vector  Disease includes high fevers, muscle aches, cough, nausea, vomiting, high heart/respiratory rate, pulmonary edema, and hemorrhagic fever  Treatment via anti-viral therapy and intubation  Other comments o Hemorrhagic fever with renal failure in Asia and Europe o Pulmonary syndrome via Sin Nombre Hantavirus in S.W. United States o Diagnosis and confirmation via serological testing for anti-viral antibodies Hepatitis D virus (HDV) (delta virus)  Enveloped (-) ssRNA w/ RNA-dependent RNA polymerase  Transmission via blood or bodily fluids  Disease includes a coinfection or superinfection that potentiates the morbidity associated with HBV  Other comments o This is considered to be a defective virus that requires hepatitis B virus (HBV) to replicate