Info

Nonstructural

RNA binding

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Fig. 2 Drawing showing the organization of the various rotavirus structural proteins. (View this art in color at www.dekker.com.)

TYPING, ANTIGENS AND ANTIGENIC VARIATION

Serogroups

Rotaviruses are subdivided into seven groups (Table 2). These serogroups are determined by epitopes on VP6 which forms the inner capsid. Of these, humans are infectable by groups A, B, and C, as are many other animal species. Most human infections are due to group A rotaviruses. Group B rotaviruses are associated with large epidemics of disease in adults and children alike.[8,9] Group C rotaviruses usually cause only mild disease and by adulthood 30% have antibodies. VP6 is the most abundant viral protein (780 molecules per virion) and the group-specific epitopes are localized between amino acids 48 and 75. Although antibodies to group epitopes are nonneutralizing in vitro they do give protection in mice.

Group A rotaviruses can be further divided into subgroups based on other, as yet undefined, epitopes on VP6. Four subgroups are possible: I, II, I and II, and neither.

Serotypes

There are two major serotype antigens: on VP4, the P (protease sensitive) type, and on VP7, the G (glycopro-

Table 2 Reservoirs of different rotavirus groups

Group Reservoirs in which infection has been detected

A Man, primates, horse, sheep, pig, cattle, dog, cat, turkey, chicken, mice

B Man, pigs, cattle, sheep, rats

C Man, pigs, cattle, ferret

D Chicken, turkey

E Pigs

F Chicken

G Chicken teins) type. These are expressed on the surface of the virus and antibodies to P and G epitopes are protective against infection.

VP4 forms the 60 knobs that protrude from the virion surface. It is nonglycosylated and makes up only 1.5% of the virion protein. Cleavage of VP4 (to VP5* and VP8*) stabilizes the knobs which become icosahedrally ordered. VP5* forms the body and base of the knob in p-pleated sheets and a-helices, respectively, VP8* forms the head in p-sheets, and both are involved in virus entry by permeabilization. Monoclonal anti-VP4 antibodies neutralize infectivity, and by use of such antibodies a number of different P-serotypes have been defined (Table 3).

Table 3 Group A rotavirus P-serotypes and genotypes

Human

Table 3 Group A rotavirus P-serotypes and genotypes

Human

Genotype

Serotype

pathogen

Other animals

[1]

Getting Started With Dumbbells

Getting Started With Dumbbells

The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.

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