Reoviruses

reo: respiratory enteric orphan, early recognition that the viruses caused respiratory and enteric infections incorrect belief they were not associated with disease, hence they we re considered "orphan " viruses

Point mutations - RNA polymerase has a high error rate.

 The family Reovirida 15 genera Four of the genera are able to infect humans and animals: OrthoreovirusRotavirus Orbivirus Coltivirus GenusSegmentsHostVector Orthoreovirus10MammalsNone Orbivirus11MammalsMosquitoes, flies Rotavirus11MammalsNone Coltivirus12MammalsTicks

Rotaviruses

 Rota: from Latin rota, "wheel"  Rotaviruses are stable to: heat at 50°C to a 3.0–9.0 range of pH to lipid solvents, such as ether and chloroform but they are inactivated by 95% ethanol, phenol, and chlorine.

 Rotaviruses cause of diarrheal illness  Diarrhea: from the Greek dia (through) and rhein (to flow).  Rotaviruses have a wide host range.

 Infect cells in the small intestine.  multiply in the cytoplasm of enterocytes & demage their transport mechanism.  NSP4 One of the rotaviruses – encoded protein Is a viral enterotoxin Diarrhea caused by rotaviruses may be due to impaired sodium, calcium and glucose absorption

 Trigger the intestinal nervous system to secrete more water Many people with dirrhea don’t dare to leave bathroom

 Cause the diarrhea illness in infants & children  Incubation period 1 – 3 days Typical symptom :  Watery diarrhea  fever  Abdominal pain  Vomiting fatal  Dehydration ( can be fatal )  In children with immunodeficiencies can cause severe & prelonged diseases.

 up to 50 % of causes of acute gastroenteritis in young children  predominate during the winter season.  in children 6 months - 2 years.  Transmission by the facel-oral route.  IgA or Interferon are important to protect this infections.

Virus in stool is demonstrated by :  Enzyme immunoas (EIA) : (more sensitive)  IEM ( less sensitive) PCR :  For Genotyping of rotaviruses nucleic acid from stool ELISA test :  is used to detect antibody titer rise

 Management replacement of fluids  Control : Wastewater treatment & sanitation.  1998 vaccine (rhesus) was discoverd for infants it causes intussusception ( bowel blockages )  2006 : oral bovine-based vaccine.  2008 : oral human-based vaccine.

 gastrointestinal & upper respiratory tracts  Usually asymptomatic  occasionally producing mild febrile illness,

 Infects insects & infects vertebrates  Not cause serious human disease  Cause mild fever  Like : bluetongue viruse of sheep AND cattles African horse sickness virus

Colorado tick fever virus ( transmitted by ticks) is able to infect humans. (more in USA )

 Picornaviridae  Smallest of the animal viruses  Picornaviruses that cause human disease are in several genera  Rhinovirus, Enterovirus, and Hepatovirus  Caliciviridae, Astroviridae, and Hepeviridae  Larger than picornaviruses  Cause gastrointestinal disease

 Caliciviruses and astroviruses  can cause acute gastroenteritis  Can cause outbreaks in day care centers, schools, and hospitals  Caliciviruses cause diarrhea, nausea, and vomiting  Astroviruses cause diarrhea, less vomiting  No specific treatment except replacement of fluid and electrolytes  Different in size, absence of some enzymes (helicase) in astroviruses

- Oral- fecal transmissin - More diarrhea in children and more vomiting in adults -PCR, EM, ELISA and RIA (Ag and Ab) - (Low number in stool) - Electrotherapy, ORS - Bismuth subsalicylate Caliciviruses

 28 – 30 nm  Star-like merfology  Single-strand & positive-sense genome  Like : Mamastrovirus  Cause diarrheal  Are transmitted by : food or water contact the fecal–oral route

-Oral- fecal transmissin, generally sporadic - Important in children and immunosuppressive people % diarrhea in HIV + people - PCR, EM (High number in stool (EM)) - Electrotherapy, ORS - More in Asia and in winter Astroviridae