Reo Viruses:

 

Respiratory Enteric Orphan (REO) viruses infect human respiratory system and intestinal tracts; they donít manifest any symptoms that are why they are called orphan viruses i.e. they are in search of a disease.† But now it is known that they do cause diseases such as infantile Diarrhea and Colorado tick fever and others.† There are more than 150 species; they infect animals and plants as well. They include Rotavirus.

 

 

Aqua Reo virus; http://www.colgate.edu/

 

 

 

One more diagram of Reovirus depicting various structural features; http://www.microbiologybytes.com/

 

Genus:

Outer capsid:

Core:

Non-structural:

Reoviruses:

σ-1, σ-3, μ-1c, λ-2

λ-1, λ-3, σ-2, μ-2

μ-NS, σ-NS

Orbiviruses:

VP2, VP5, VP7

VP3;
VP1,VP4,VP6 (transcriptase complex)

NS1, NS2, NS3

Rotaviruses:

VP4, VP7

VP2, VP6, VP1, VP3

NSP1, NSP2, NSP3, NSP4, NSP5, NSP5A

††††††††††† Microbiology bytes ; http://www.microbiologybytes.com/

 

 

General features:

 

All have isometric shape, naked, 70 to 85 nm thick, and made up of two concentric capsid layers.

 

 

 

 

Viral Proteins:

 

Gene/protein

Mol.wt (KD)

Function

Lambda-1

155

Inner capsid (core protein)

Lambda-2

140

Inner core-Guanyl transferase

Lambda-3

140

Replicase

Micron 1C

80

Outer capsid protein

Micron 2

72-80

Inner core

Micron NS1

80

Nonstructural protein

Micron NS2

36

Nonstructural protein

Sigma 1

42

Spike, 1HA

Sigma 2

38

Inner capsid protein

Sigma 3

34

Outer capsid protein

 

 

 

 

Replication:

 

Entry is gained through the spike protein binding to cellular receptors, and endocytosis leads to endosomes.†

 

       Inside endosomes outer capsid digested to release †inner core, which now becomes active.

 

This figure shows the infection and reproductive cycle of the virus;

Development of Oncolytic Reovirus for Cancer Therapy; Ergin Sahin; http://file.scirp.org/

 

 

There are 10-(11?) dsRNA genomes, each code one or more proteins,

 

       The RNA dependent RNA polymerase or what is called RNA Replicase start replicating to produce only positive sense RNA from all the ten segments, as each transcript represents one protein.†

 

       What is not clear, but speculated, whether or not the ds RNA fully formed RNAs or one of them especially (+) strand is incomplete, at the time of infection.

 

       Aftermath of infection and activation, the incomplete plus strands of RNA are completed and the same are released into cytoplasm.† The released (+) RNAs have cap structure at 5í end with out a poly (A) tail.

 

       The negative RNA strands also have pppG-Pu-Py sequences at the 5í end.† The plus sense RNAs, as they are synthesized, they come out of the pores found at vertices.†† It is through the pores in the capsid, all the required NTPs and other components for replication enter. Even the RNA strands synthesized inside the viral capsid move out.

 

       Synthesis and the release of (+) RNAs continue.† The (+) RNA transcripts in cytoplasm act as mRNAs and they associate with ribosomes and translate.

 

       As sufficient number of the inner capsid proteins and replicating enzymes are produced, they get assembled into provirus particles with all ten different species of (+) RNAs.†

 

       Within these cores particles, plus RNAs are transcribed or say replicated to generate (-) RNAs.† Pro- viral particles continue to produce more (+) RNAs and more proteins and more (-) RNAs.†

 

       As process goes on, many pro-viral cores with ds RNAs get encapsulated with second coat proteins to produce new viral particles.†

Many of the mechanisms are not well understood (or I havenít got the material to know about it?).