Reovirus, Calicivirus, GIT Viruses PDF

Microbiology Reoviruses, Calicivirus, and Gastrointestinal Viruses MEM, MD REOVIRIDAE ROTAVIRUS  Respiratory, Enteric, Orphan (REO)  R...

Microbiology Reoviruses, Calicivirus, and Gastrointestinal Viruses MEM, MD REOVIRIDAE ROTAVIRUS  Respiratory, Enteric, Orphan (REO)  Rota  “Wheel”  Respiratory and enteric viruses that are not associated  95% of children are infected by 3-5 years old with any known disease process  Stable at room temperature, treatment with detergents, 1. Orthoreovirus pH 3.5-10 (acidic to alkaline), survives on fomites o Mild URT Illness, GIT Illness,  Infectivity is enhanced by proteolytic enzyme such as Biliary Atresia Trypsin 2. Orbivirus / Coltivirus 1. Serotypes  based primarily on VP7 outer o Febrile Illness associated with capsid protein Members Headache and Myalgia 2. Groups  based on antigenicity of VP6 (Zoonosis) and electrophoretic mobility of genomic 3. Rotavirus Divided segments  A to G; Group A causes human o GIT Illness, Respiratory Tract Into: disease Illness (?) 3. Subgroups  determined by Complement  Non-Enveloped; Double-layered protein capsids with Fixation and depend on VP6 inner capsid dsRNA genomes (“double:double”) protein o Double-Layered Capsid + Double-Stranded RNA PATHOGENESIS genome  MOT: Fecal-Oral Route, possibly Respiratory Route  Resistant to environmental and GIT conditions  Adsorption to Columnar Epithelial Cells covering Villi of  Icosahedral with Double-Stranded Small Intestine  release of NSP4 Protein  (+) Cytolytic Segmented Genome and Toxin-Like Activity  loss of electrolytes and o Reovirus – 10 segments prevention of water re-absorption  Watery Diarrhea  o Rotavirus – 11 segments Severe Dehydration  (+) Re-assortment of Gene  NSP4 Protein Promotes: Segments  create HYBRID 1. Calcium Influx into Enterocytes Structure VIRUSES 2. Release of Neuronal Activators  Outer Capsid composed of 3. Neuronal Alteration in Water Absorption Structural Proteins  Shortening and blunting of Microvilli; Mononuclear Cell  Genomic segments encode Infiltration into Lamina Propia Structural and Non-Structural  1010 Viral Particles/gm of Stool released during disease  Proteins Maximal Shedding 2-5 days after start of Diarrhea REPLICATION  (+) outbreaks in pre-schools and daycare centers Ingestion  Upon ingestion, CLINICAL SYNDROMES there is proteolytic  Incubation Period: 48 hours cleavage of the  Self-Limited Proteolytic Cleavage of Outer Outer Capsid in the Capsid in GIT  Vomiting, Diarrhea, Fever, Dehydration GIT  (-) Fecal Leukocytes and Blood  From there, there  May be fatal in infants from developing countries and Formation of Intermediate / Infectious Viral Particle (ISVP) will be formation of infants who are malnourished and dehydrated before ISVP that will be infection ISVP release Core into released in the  Causes longer and more severe diseases compared to Cytoplasm Cytoplasm other viral antigens  Seizures and other milder  These enzymes neurological signs are common Enzymes in Core initiate mRNA within the Core will  Production using (+) Strand as initiate mRNA Template LABORATORY DIAGNOSIS production  Direct detection of viral antigens in stool  METHOD OF  Occurs in the CYTOPLASM CHOICE  dsRNA remains in the CORE  Enzyme Immunoassay  Inner Capsid with complete transcription system,  Latex Agglutination including enzymes for 5’ capping and polyadenylate  Serology – four-fold increase in Antibody titer addition PREVENTION  Virus leaves the during CELL LYSIS  Rotateq (RV5) ORTHOREOVIRUS o Oral Attenuated Live Vaccine  Mammalian Reovirus o Can be given to infants from 6 months to 2 years old  Ubiquitous  present in sewage and river water o 3 Dose before 15 weeks of age:  3 Serotypes (1, 2, 3)  identification is based on Should be completed by 8 months Neutralization and Hemagglutination-Inhibition Tests Given 6 weeks, 3 months, 5 months  Most people infected during childhood  (+) Antibodies  Rotatrix (RV1) in 75% of adults infected during childhood o Given 2 doses at age 2 months and 4 months PATHOGENESIS AND IMMUNITY COLTIVIRUS AND ORBIVIRUS  No significant disease in humans FEATURES DIFFERENT FROM OTHER REOVIRIDAE  After ingestion and proteolytic production of ISVP, binds ORBIVIRUS to M Cells in Small Intestines  transfer virus to  Outer Capsid without discernible capsomeric structure; Lymphoid Tissue of Peyer’s Patches  Replicate  (+) Inner Capsid is Icosahedral Viremia  Causes Viremia  long-lasting  (+) Humoral and Cellular Immune Response to Outer  Infects Erythrocyte Precursors without damaging them Capsid Protein  remains within the cells  protected from immune CLINICAL SYNDROMES response  (+) Viremia  Usually ASYMPTOMATIC COLTIVIRUS  Common cold-like mild Upper Respiratory Tract Illness  Causes Colorado Tick Fever  Gastrointestinal Disease  Vector: Dermacentro andersoni (Wood Tick)  Biliary Atresia  One of the most common tick-borne diseases in the US LABORATORY DIAGNOSIS  Symptoms of acute disease resemble Dengue  Assay of Viral Antigen or RNA in clinical material  Infect Vascular Endothelial and Vascular Smooth  Virus Isolation Muscle Cells and Pericytes  Weak Capillary Structures  Serologic Assays  (+) Hemorrhage  Hypotension  Shock Page 1 of 2  Microbiology Reoviruses, Calicivirus, and Gastrointestinal Viruses MEM, MD  Neuronal Infection  Meningitis and Encephalitis  MOT:  (+) Leukopenia involving both Neutrophils and o Primarily: Oral-Fecal Route Lymphocytes  HALLMARK o Airborne droplets of vomitus can cover a large radius LABORATORY  Few virus is needed  Immunofluorescence – most rapid and best technique  to start a large detection of viral antigen on surface of RBCs on Blood outbreak Smear  MOT is primarily of  Antibody Titer - specific IgM (+) 45 days after onset of Fecal-Oral Route illness  presumptive evidence of acute or very recent  Airborne particles infection from vomitus are CALICIVIRUSES capable of covering A. Norwalk a large radius B. Sapporo Viruses  Survive in chlorinated water at routine levels (up to 10 5 Groups C. Rabbit Hemorrhagic Disease Virus ppm) in freezing, heating up to 60C D. Marine Virus  Acute Gastroenteritis/Stomach Flu E. Hepatitis E  Viral Shedding: up to 2 weeks  Approximately same size as Picornaviruses  No evidence of long-term carrier  Naked, Positive Sense ssRNA Viruses DIAGNOSIS  Viruses distinguishable by Capsid morphology  Specimen: stool, vomitus, food, environmental swabs compromise function of intestinal brush border  (during outbreak) Prevent reabsorption of water and nutrients  RT-PCR, Serology  Infection results in delayed gastric emptying although  CDC recommends environmental disinfection of non- gastric mucosa is normal porous surfaces with 1000 ppm bleach solution (1 part  Cause outbreaks of Non-Bacterial Gastroenteritis bleach : 50 parts water) CLINICAL FEATURES SAPOROVIRUS  Incubation Period: 24-48 hours  Typical Morphology:  MOT: o (+) ssRNA, icosahedral, single capsid, 32 cup-like a. Fecal-Oral  water, shellfish, food service depressions b. Possible Airborne  EM: appearance of “Star of David”  e.g., Sapporo-Like  Immunity is short-lived and not protective Viruses  Antibodies develop after the first 72 hours after the  Sporadic cases and occasional outbreaks of diarrheal onset of illness illness in infants, young children, and elderly adults  Symptoms similar to Rotavirus Infection GASTROINTESTINAL VIRUSES  Norwalk and Related Viruses  Diarrhea, Nausea and ASTROVIRUSES Vomiting, especially in children; Fever in 1/3 of patients  Small ssRNA virus, non-enveloped,  Resolve within 12-60 hours round with an unbroken smooth  EM: surface o Star of David  cup-shaped on capsid surface  EM: 5- or 6-pointed star within smooth o Cuplike depression on capsid surface edge Characteristics  Typically associated with Respiratory, Vesicular,  Contain 3 structural proteins Hemorrhagic Disease, Gastroenteritis  Infect monolayers of human NOROVIRUS (NORWALK VIRUS) embryonic kidney cells without  Morphology: Atypical Morphology producing cytopathic effects  Smooth Surface  Human Serotypes: HuAstV 1-8  Small, round, structured viruses (e.g., Norwalk-like  Seen in stools from infants and young children with or Viruses) without Acute Gastroenteritis  Resistant to environmental pressure  detergents,  Agents in star-shape associated with Diarrhea in young drying, and acid children in daycare centers  Important cause of Epidemic Viral Gastroenteritis in  Symptoms similar to Norwalk but WITHOUT VOMITING adults  MOT: person-to-person via fecal-oral  Disease resolves after 48 hours, without serious  Outbreaks due to fecal contamination of seafood or consequences water  3 Genogroups Associated with Human Gastroenteritis; FASTIDIOUS ADENOVIRUS o GI, GII, and GIV  Replicates in Intestinal Cells o Since 2001, Genotype GII.4 Viruses have caused most  Adenovirus Group F Serotypes 40 and 41  Infantile Viral Gastroenteritis outbreaks worldwide Gastroenteritis  detected by electron microscopy or  Appears to undergo Antigenic Drift over time  Antigen-Based Assays, usually SUBCLINICAL responsible for GII.4 Virus  Onset of illness is manifested by Diarrhea in young child  Cellular Receptors:  May have Cough, Rhinorrhea, or Wheezing o Histo-Blood group antigens that are expressed on the  Pneumonia and Conjunctivitis have also been associated mucosal epithelia of the digestive tract with Adenovirus Conjunctivitis  A person’s secretor status is controlled by  Seen in feces of patients for a period of 4 days to 2 weeks Fucosyltransferase 2 Gene GASTROINTESTINAL DUE TO ADENOVIRUS o Secretor-Negative individuals are resistant to  MOT: Fecal-Oral Route infection with common strains of Norwalk Virus  Incubation Period: 3-10 days CLINICAL FEATURES  Age Group Affected: