A product selected from the group consisting of: (a) a polynucleotide encoding a polypeptide comprising (i) a first component comprising a secretory pathway signal peptide, and (ii) a second component comprising the minimum region of an Orthoreovirus muNS protein having the capacity to form inclusions when expressed in a cell or a functionally equivalent variant thereof showing at least 70% sequence identity with respect to the sequence of the minimum region of an Orthoreovirus muNS protein and maintaining the capacity to form inclusions when expressed in a cell, wherein the first component is located in the N-terminal position with respect to the second component; (b) a polypeptide encoded by the polynucleotide according to (a); (c) a polynucleotide encoding a fusion protein comprising: (i) a first component comprising a secretory pathway signal peptide, (ii) a second component comprising a polypeptide of interest, and (iii) a third component comprising the minimum region of an Orthoreovirus muNS protein having the capacity to incorporate itself into inclusions formed by a protein comprising the minimum region of an Orthoreovirus muNS having the capacity to form inclusions when expressed in a cell or a functionally equivalent variant thereof, wherein the functionally equivalent variant shows at least 70% sequence identity with respect to the sequence of the minimum region of an Orthoreovirus muNS protein having the capacity to incorporate itself into inclusions, and wherein the functionally equivalent variant maintains the capacity to incorporate into inclusions formed by a protein comprising the minimum region of an Orthoreovirus muNS having the capacity to form inclusions when expressed in a cell, wherein the first component is located in the N-terminal position with respect to the second and third components; and (d) a fusion protein encoded by the polynucleotide according to (c). (a) a polynucleotide encoding a polypeptide comprising (i) a first component comprising a secretory pathway signal peptide, and (ii) a second component comprising the minimum region of an Orthoreovirus muNS protein having the capacity to form inclusions when expressed in a cell or a functionally equivalent variant thereof showing at least 70% sequence identity with respect to the sequence of the minimum region of an Orthoreovirus muNS protein and maintaining the capacity to form inclusions when expressed in a cell, wherein the first component is located in the N-terminal position with respect to the second component; (i) a first component comprising a secretory pathway signal peptide, and (ii) a second component comprising the minimum region of an Orthoreovirus muNS protein having the capacity to form inclusions when expressed in a cell or a functionally equivalent variant thereof showing at least 70% sequence identity with respect to the sequence of the minimum region of an Orthoreovirus muNS protein and maintaining the capacity to form inclusions when expressed in a cell, wherein the first component is located in the N-terminal position with respect to the second component; (b) a polypeptide encoded by the polynucleotide according to (a); (c) a polynucleotide encoding a fusion protein comprising: (i) a first component comprising a secretory pathway signal peptide, (ii) a second component comprising a polypeptide of interest, and (iii) a third component comprising the minimum region of an Orthoreovirus muNS protein having the capacity to incorporate itself into inclusions formed by a protein comprising the minimum region of an Orthoreovirus muNS having the capacity to form inclusions when expressed in a cell or a functionally equivalent variant thereof, wherein the functionally equivalent variant shows at least 70% sequence identity with respect to the sequence of the minimum region of an Orthoreovirus muNS protein having the capacity to incorporate itself into inclusions, and wherein the functionally equivalent variant maintains the capacity to incorporate into inclusions formed by a protein comprising the minimum region of an Orthoreovirus muNS having the capacity to form inclusions when expressed in a cell, wherein the first component is located in the N-terminal position with respect to the second and third components; and (i) a first component comprising a secretory pathway signal peptide, (ii) a second component comprising a polypeptide of interest, and (iii) a third component comprising the minimum region of an Orthoreovirus muNS protein having the capacity to incorporate itself into inclusions formed by a protein comprising the minimum region of an Orthoreovirus muNS having the capacity to form inclusions when expressed in a cell or a functionally equivalent variant thereof, wherein the functionally equivalent variant shows at least 70% sequence identity with respect to the sequence of the minimum region of an Orthoreovirus muNS protein having the capacity to incorporate itself into inclusions, and wherein the functionally equivalent variant maintains the capacity to incorporate into inclusions formed by a protein comprising the minimum region of an Orthoreovirus muNS having the capacity to form inclusions when expressed in a cell, wherein the first component is located in the N-terminal position with respect to the second and third components; and (d) a fusion protein encoded by the polynucleotide according to (c).