MULTICISTRON EXPRESSION VECTOR FOR COVID-19 VACCINE

1 . An expression vector construct encoding more than one structural protein of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) comprising:

a) promoter sequence;

b) untranslated regions;

c) more than one structural protein selected from spike(S), envelope (E), membrane (M), and nucleocapsid (N);

d) one or more internal Ribosome Entry Site (IRES) element; and

e) polyadenylation (poly A) tail.

2 . An expression vector construct encoding more than one structural protein of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) comprising:

a) promoter sequence;

b) 5′ untranslated region (5′ UTR);

c) internal ribosomal entry sites (IRES) element;

f) one or more structural proteins of SARS-COV-2 selected from spike(S), envelope (E), membrane (M), and nucleocapsid (N);

d) internal ribosomal entry sites (IRES) element;

e) 3′ untranslated region (3′ UTR); and

f) polyadenylation (Poly A) tail.

3 . The expression vector construct as in claim 1 or claim 2 , wherein the SARS-COV-2 variant is selected from alpha, beta, gamma, delta, eta, Iota, kappa, lambda, and Mu.

4 . The expression vector construct as in claim 1 , wherein the expression vector encoding more than one structural proteins of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) comprising:

a) T7 promoter;

b) 5′ Untranslated region (5′ UTR);

c) spike protein of SARS-COV-2 delta variant;

d) internal Ribosome Entry Site (IRES) element;

e) envelope protein of SARS-COV-2 delta variant;

f) internal Ribosome Entry Site (IRES) element;

g) membrane protein of SARS-COV-2 delta variant;

h) internal Ribosome Entry Site (IRES) element;

i) nucleocapsid protein of SARS-COV-2 delta variant;

j) 3′ Untranslated region (3′ UTR); and

k) poly(A) tail.

5 . The expression vector construct as in claim 4 has nucleotide sequence as set forth in SEQ ID NO.: 1.

6 . The expression vector construct comprises polyadenylation (Poly A) tail as in claim 1 or claim 2 or claim 4 , wherein the Poly A tail contains about 80 to about 120 adenosine nucleotides.

7 . The expression vector construct comprises polyadenylation (Poly A) tail as in claim 6 , wherein the Poly A tail contains 110 adenosine nucleotides.

8 . The expression vector construct comprises SARS-COV-2 spike(S) protein as in claim 1 or claim 2 or claim 4 , wherein the length of spike(S) protein from about 1250 to about 1290 amino acid residues.

9 . The expression vector construct comprises SARS-COV-2 envelope (E) protein as in claim 1 or claim 2 or claim 4 , wherein the length of envelope (E) protein from about 50 to about 90 amino acid residues.

10 . The expression vector construct comprises SARS-COV-2 membrane (M) protein as in claim 1 or claim 2 or claim 4 , wherein the length of membrane (M) protein from about 200 to about 250 amino acid residues.

11 . The expression vector construct comprises SARS-COV-2 nucleocapsid (N) protein as in claim 1 or claim 2 or claim 4 , wherein the length of nucleocapsid (N) protein from about 390 to about 446 amino acid residues.

12 . The expression vector construct as claimed in claim 1 or claim 2 or claim 4 , expresses the mRNA capable to encode one or more structural protein provides immune response against SARS-COV-2 virus.

13 . A process for the purification of mRNA comprises;

a) transfect the expression vector as claimed in claim 1, claim 2 or claim 4 into E. Coli host cells;

b) harvesting of cells followed by lysis, neutralization, and precipitation;

c) isolation and purification of plasmid;

d) linearization of purified plasmid;

e) performing the in-vitro transcription reaction for the preparation mRNA;

f) purification of mRNA by chromatography methods.

14 . The purification of mRNA as claimed in claim 13 is purified using suitable chromatography selected from high performance liquid chromatography (HPLC), low normal pressure liquid chromatography method, gas chromatography, reversed phase HPLC (RP-HPLC), affinity chromatography, mixed-mode chromatography, ion exchange chromatography, hydroxyapatite chromatography, core bead flow-through chromatography, Oligo dT chromatography.