Sessions 15-16 - RNA viruses (1).pptx

RNA viruses Imaan Benmerzouga, Ph.D. [email protected] 03/12/2024 Certificate in Health Professional Program Spring 2024 Session 15 & 16 Learning Objectives 1. Recall the properties and replication strategies of Measles virus(M) Mumps virus (M), Respiratory Syncytia virus (RSV), Influenza virus, Han...

RNA viruses Imaan Benmerzouga, Ph.D. [email protected] 03/12/2024 Certificate in Health Professional Program Spring 2024 Session 15 & 16 Learning Objectives 1. Recall the properties and replication strategies of Measles virus(M) Mumps virus (M), Respiratory Syncytia virus (RSV), Influenza virus, Hantavirus, Rabies virus, Coronaviruses, Enteroviruses and Rubella 2. Identify the diseases associated with infections of Measles virus(M) Mumps virus (M), Rubella virus (R), Respiratory Syncytia virus, Influenza virus, Enteroviruses, Coronaviruses, Hantavirus, and Rabies virus. 3. Identify the pathogenesis of each virus and its relevance in disease. 4. Recall the mode of transmission of Measles virus(M) Mumps virus (M), Rubella virus (R), Respiratory Syncytia virus, Influenza virus, Enteroviruses, Coronaviruses, Hantavirus, and Rabies virus. 5. Recognize the approaches used for diagnosing infections with these viruses and related treatments. RNA Viral Classification Family -viridae MMvirus Genus -virus Paramyxo Morbilli (Measles) RSV Genome Envelope -ssRNA + Pneumo Rubula (Mumps) Pneumo -ssRNA + Influenza Orthomyxo Influenza -ssRNA + Hantavirus Bunya Hantavirus -ssRNA + Rabies Rhabdo Lyssa -ssRNA + Coronavirus Corona Corona +ssRNA + Toga Rubi (Rubella) +ssRNA + Picorna Enterovirus (Coxsackievirus, Poliovirus, enterovirus and Echovirus) +ssRNA - Enteroviruses RNA Viral Classification- introduction videos Family -viridae MMvirus Paramyxo Genus -virus Morbilli (Measles) https://www.youtube.com/watch?v=RMg5aO1kXeY Genome Envelope -ssRNA + Rubula (Mumps) https://www.youtube.com/watch?v=Akr5SJQEv_0 RSV Paramyxo Subfamily: Pneumovirinae) Pneumo https://www.youtube.com/watch?v=eXLvkQy5JQc -ssRNA + Influenza Orthomyxo Influenza https://www.youtube.com/watch?v=tB5FQZi4HKY -ssRNA + Hantaviru s Bunya Hantavirus https://www.youtube.com/watch?v=x13fIkGGKIE -ssRNA + Rabies Rhabdo Lyssa https://www.youtube.com/watch?v=_tMORbU5c3Y -ssRNA + Coronavir us Corona Corona https://www.youtube.com/watch?v=8hgc2iZflTI +ssRNA + Toga Rubi (Rubella) https://www.youtube.com/watch?v=uLMROk2nK1w +ssRNA + Picorna Enterovirus (Coxsackievirus, Poliovirus, enterovirus and Echovirus) https://www.youtube.com/watch?v=S6Yg2KHrzlw +ssRNA - Enterovir uses Paramyxoviruses Paramyxoviridae (family) Paramyxovirinnae (subfamily) Rubulavirus (mumps virus) Morbillivirus (measles virus) Paramyxovirus (parainfluenza viruses) Pneumovirinae,(subfamily) Pneumovirus (RSV) Metapneumovirus (hMPV) Properties  -ssRNA  Helical capsid  Enveloped  Encodes 6-10 genes on 1 segment  Human diseases caused by this family: Parainfluenza, causes upper respiratory tract infections, Mumps, Measles, RSV and metapneumovirus Paramyxoviridae Properties (cont)  H stands for hemagglutinin and N for neuraminidase)  Surface glycoproteins are important for viral binding  The N activity is needed if the glycoprotein binds sialic acid (such as HN)  F stands for fusion - facilitates virus entry to cytoplasm by fusing virial and cellular membranes Epidemiology: Worldwide, some are seasonal Transmission: Inhalation of large droplet aerosols Live attenuated vaccine available Immune serum globin can be administrated after exposure Lippincott's Illustrated Reviews: Microbiology, 3e Paramyxoviridae Pathogenesis  Virus binds via HN or other glycoproteins present on the surface of the envelope to deliver its genome into the cell (paramyxoviuses differ in the surface glycoproteins)  HN binds to sialic acid on the surface of glycoproteins and glycolipids of the cell membrane and requires N activity to cleave salic acid on viral or cellular glycoproteins, prevents self-binding and binding to infected cells  The capsid contains RNA polymerase  New genome associate with capsid proteins  Mature virions bud off the cell and exit without cell lysis  The receptors that Measles bind to are present on may cell types  measles can infect many cell types Medical Microbiology, 55, 550-564.e1 Clinical Disease (measles) Paramyxoviridae  Incubation 7-10 days  Prodrome starts with 2 -4 days of high fever, CCC and P (cough, coryza, conjunctivitis , and photophobia)-most contagious time  After 2 days of prodromal illness, the mucus membrane lesions (Koplik spots) Koplick Spots appear  Within 24 hours of Koplick spots, a rash spreads starting below the ears and over body  The day the rash appears, the patient is sickest and highest fever  Complications such as: pneumonia with bacterial super infection and most feared negative outcomes on the central nervous system: encephalitis or Subacute sclerosing panencephalitis (SSPE) that occurs many years after measles infection Measles rash  After resolution-life long immunity Time course of measles Medical Microbiology, 55, 550-564.e1 Paramyxoviridae Clinical Disease (Mumps)  Fever  Bilateral swelling of the salivary glands (parotitis)  Swelling of other glands occurs  Rare outcomes: encephalitis  Orchitis may cause sterility  HN protein of the mumps virus binds sialic acid of the epithelial cells of the upper respiratory tract, moves to the parotid gland via viremia or the Steensen duct, viremia allows the virus to reach testis, ovary, pancreas, thyroid and other organs (inflammatory response causes the swelling) Medical Microbiology, 55, 550-564.e1 Paramyxoviridae Laboratory Diagnosis Measles: Immunofluorescence: antigens detected in urinary sediment or blood sample RT-PCR: genome detected in sample Microscopy: cytopathological changes detected using Giemsa- staining (multinucleated cells) Mumps: RT-PCR (detect viral genome) enzyme-linked immunosorbent assay (ELISA): Mumps IgM or antigen Cell culture: isolated virus from sample (saliva, urine, CSF or secretions from Steensen's duct) and culture in monkey kidney cells causing multinucleated cells Paramyxoviridae Treatment prevention and control Measles:  Live attenuated vaccine given in an MMR vaccine (only one serotype, so eradication is possible but limited because of difficulties delivering the vaccine to some regions (Africa)  Exposed susceptible people who are immunocompromised can be given immunoglobin (most effective if given without 6 days of exposure)- World health organization recommends high dose vitamin A to reduce measles mortality  No antivirals Mumps:  Live attenuated vaccine given in the MMR mix at 1 year of age, some states require re-vaccination in early childhood/teenage years  2014: Outbreak in Columbus, Ohio  No antivirals Pneumovirinae Clinical Disease (RSV)  Major virus in pediatric population- mostly winter, does not skip a year  Infection localized to the respiratory tract (no viremia)  Most common cause of fatal acute respiratory tract infection in infants and young children  Infects everyone by age of 2, and reoccurs throughout life  Pathological effects of RSV are a result of immune-mediated cell injury  Neutrophils play a major role, necrosis bronchi, bronchioles, small airway result in the formation of “plugs” from mucus, fibrin or necrotic material – obstructing airways in infants Disorder Age group Bronchiolitis, pneumonia, or both Infants (children