Structure, clinical features, diagnosis, treatment and vaccine

1. Rota virus
Dr Mayuri Rani

2. Virus
➔ Rotavirus has a characteristic wheel-like appearance when viewed by an electron
microscope
➔ The name rotavirus is derived from the Latin word rota, meaning “wheel.”
➔ Rotaviruses are non-enveloped, possess a triple-layered capsid, and have a
segmented RNA genome.

3. Transmission electron micrograph of intact
rotavirus particles. This digitally colorized
image reveals structure of rotavirus virions
(viral particles).

4. Antigenic structure
➔ Rotaviruses are 70-nm nonenveloped RNA viruses in the family Reoviridae
➔ The viral nucleocapsid is composed of 3 concentric shells that enclose 11 segments of double-
stranded RNA.
➔ The outermost layer contains two structural viral proteins (VP): VP4, the protease-cleaved protein (P
protein) and VP7, the glycoprotein (G protein).
➔ These two proteins define the serotype of the virus and are considered critical to vaccine development
because they are targets for neutralizing antibodies that are believed to be important for protection.

5. Typing system
➔ Because the two gene segments that encode these proteins can segregate independently, a
typing system consisting of both P and G types has been developed.
➔ Although characterizing G serotypes by traditional methods is straightforward, using these
methods for determining P serotypes is more difficult. Consequently, molecular methods are
used almost exclusively to define genetically distinct P genotypes by nucleotide sequencing.
➔ These genotypes correlate well with known serotypes, but they are designated in brackets
(e.g., P[8]) to distinguish them from P serotypes determined by antigenic analyses.

6. Serogroups
➔ Rotaviruses are classified into 7 different serogroups (A–G), on the basis of the antigenic
specificity of the capsid proteins in the virus, as well as on the basis of the pattern of the
electrophoretic mobility of the 11 RNA segments of the viral genome.
➔ Of the 7 rotavirus serogroups, only groups A–C are known to infect humans, and
group A rotaviruses are viruses that cause severe, life-threatening disease in children
worldwide.

7. Clinical Features
➔ Rotavirus disease is characterized by vomiting and watery diarrhea for three to
eight days.
➔ Fever and abdominal pain also are common.
➔ Additional symptoms include loss of appetite and dehydration.
Symptoms of dehydration include
● decreased urination
● dry mouth and throat
● feeling dizzy when standing up
● crying with few or no tears and
● unusual sleepiness or fussiness.

8. ➔ The incubation period for rotavirus disease is approximately two days.
➔ Children may develop rotavirus disease more than once because neither
vaccine nor natural infection provide full immunity from future infections.
➔ A child’s first infection with rotavirus tends to cause the most severe symptoms.

9. Epidemiology
➔ The primary mode of transmission is the fecal-oral route, usually through direct contact
between people.
➔ Because the virus is stable in the environment, transmission also can occur through
ingestion of contaminated water or food and contact with contaminated surfaces or objects.
➔ In the United States and other countries with a temperate climate, the disease has a winter
and spring seasonal pattern, with annual epidemics occurring from January through June.
➔ The highest rates of illness occur among infants and children age 5 and under. Adults
can get rotavirus, though disease tends to be milder.

10. Diagnosis
➔ Nucleic acid detection PCR assays (for rotavirus alone or in multipathogen panels)
➔ Antigen-detection immunoassays on stool specimens to rapidly detect rotavirus.
➔ Characterization of strains by nucleic acid sequencing by laboratories engaged in surveillance
testing or research.

11. Treatment
➔ For people with healthy immune systems, rotavirus disease is self-limited, lasting only
a few days.
➔ Treatment is nonspecific and consists primarily of oral rehydration therapy to prevent
dehydration.

12. Vaccination
The CDC recommends routine vaccination of infants with either of the two available vaccines:
➔ RotaTeq® (RV5, Pentavalent Human-Bovine Reassortant Rotavirus Vaccine) licensed in
2006, is given in three doses at ages 2 months, 4 months, and 6 months.
➔ Rotarix® (RV1, monovalent human rotavirus vaccine) licensed in 2008, is given in two doses
at ages 2 months and 4 months