Presentation on theme: "Reoviruses. reo: respiratory enteric orphan, early recognition that the viruses caused respiratory and enteric infections incorrect belief they were not."— Presentation transcript:
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
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.
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