Rotavirus: Introduction, Morphology, Pathogenesis, Lab Diagnosis, Treat

Rotavirus: Introduction, Morphology, Pathogenesis, Lab Diagnosis, Treatment and Prevention

History of Rotavirus

Rotavirus was discovered by Ruth Bishop and colleagues in 1973 and was described as found in children with gastroenteritis. In 1974, Thomas Henry Flewett suggested the name rotavirus after observing that, when viewed through an electron microscope, a rotavirus particle looks like a wheel (rota in Latin), and later the name was officially recognized by the International Committee on Taxonomy of Viruses (ICTV) four years later. Vaccine for this virus was licensed in 1998 for use in the United States, whereas in 2009, the WHO recommended that the rotavirus vaccine be included in all national immunization programs (NIP). This virus is responsible for the leading cause of severe gastroenteritis in children worldwide, accounting for 35–40% of hospital admissions for gastroenteritis. Every year, 180 000–450 000 children under 5 years of age die from rotavirus gastroenteritis, with more than 90% of deaths occurring in developing countries.

Classification

(unranked): Virus

Realm: Riboviria

Kingdom: Orthornavirae

Phylum: Duplornaviricota

Class: Resentoviricetes

Order: Reovirales

Family: Reoviridae

Subfamily: Sedoreovirinae

Genus: Rotavirus

Species: Rotavirus A

Morphology

It is an RNA virus, icosahedral, 60-80nm, double-shelled and non – enveloped. The name rotavirus is based on the electron microscope appearance of the outer capsid margin as the rim of a wheel surrounding radiating from the inner hub-like core.

There are 2 forms:

Complete form
Incomplete form – single shelled and are 50-60 nm in diameter

The virus particle contains 11 segments of dsRNA.

The virus particle contains VPI, VP2, VP3; the inner capsid contains VP6 and the outer capsid contains VP4 and VP7.

Disease: Infantile diarrhea

Stereotypes:

There are 4 groups: ABCD

Group-A has subgroups – I and II

Subgroup- I have 1-16 serotypes.

subgroup-II has 1-9 serotypes

VP-7 is the predominant antigen of neutralizing activity.

Pathogenesis

Route of transmission: Faeco- oral route

The incubation period is approximately 2 days.

Virus multiples in the villi of the small intestine and cause lysis of the cells and also damage their transport mechanism.

Damage cells may come into the lumen of the intestine and release large quantities of viruses. (200000 virus particles per gram of stool)

Virus excretion may last 2- 12 days of infection.
Diarrhea is due to impaired sodium and glucose absorption as damaged cells on villi are replaced by nonabsorbing immature crypt cells.

It may take 3-8 weeks for normal function.

Laboratory Diagnosis

Electron Microscopy
Detection of antigen in the stool sample

Enzyme-linked immunosorbent assay (ELISA) has 90–95% sensitivity and specificity.
Immunochromatographic assays
Nucleic technology
PCR: Reverse transcription-polymerase chain reaction (RT-PCR) is widely used in research laboratories to detect the viral genome and provides data on the VP7 and VP4 genotypes that form the basis of binary classification (G and P-type, respectively) of rotavirus strains.

3. Detection of antibody in patient’s sera:

4. Virus isolation

Treatment

Oral and intravenous rehydration therapy is preferred.

Prevention

Since almost all children are affected by this virus at 5 years of age, good sanitation and hygiene alone are inadequate for prevention. Orally administered live attenuated vaccines offer the best protection against rotavirus; as of December 2013, national immunization programs in 51 countries include rotavirus vaccines. Such programs have significantly reduced gastroenteritis morbidity and mortality.

Key Notes

Infective dose: Fewer than 100 rotaviruses may transmit the infection to another person.
Rotarix and RotaTeq vaccines are available with 2 and 3 oral doses respectively.
Ages for vaccine doses vary according to the recommendations of individual countries and vaccination schedules.

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