Preparation and characterization of polyclonal antibody against severe acute respiratory syndrome-associated coronavirus spike protein

COVID-19: A review of newly formed viral clades, pathophysiology, therapeutic strategies and current vaccination tasks

Today, the world population is facing an existential threat by an invisible enemy known as severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) or COVID-19. It is highly contagious and has infected a larger fraction of human population across the globe on various routes of transmission. The detailed knowledge of the SARS-CoV-2 structure and clinical aspects offers an important insight into the evolution of infection, disease progression and helps in executing the different therapies effectively. Herein, we have discussed in detail about the genome structure of SARS-CoV-2 and its role in the proteomic rational spread of different muted species and pathogenesis in infecting the host cells. The mechanisms behind the viral outbreak and its immune response, the availability of existing diagnostics techniques, the treatment efficacy of repurposed drugs and the emerging vaccine trials for the SARS-CoV-2 outbreak also have been highlighted. Furthermore, the possible antiviral effects of various herbal products and their extracted molecules in inhibiting SARS-CoV-2 replication and cellular entry are also reported. Finally, we conclude our opinion on current challenges involved in the drug development, bulk production of drug/vaccines and their storage requirements, logistical procedures and limitations related to dosage trials for larger population.

A polyclonal antibody against recombinant bovine haptoglobin expressed in Escherichia coli

The nucleotide sequence of the predicted immunodominant region of bovine haptoglobin (pirBoHp), without the signal peptide sequence, was synthesized based on the codon usage bias of Escherichia coli. The synthesized pirBoHp gene was cloned into the prokaryotic expression vector pET-32a (+), which contains a His-tag. The recombinant pirBoHp protein was successfully expressed in E. coli BL21 (DE3) cells. Western blot analysis showed that the purified recombinant pirBoHp protein could be recognized by an anti-His-tag monoclonal antibody. Further investigations indicated that a polyclonal antibody against the recombinant pirBoHp protein could recognize the α and β chains of native bovine haptoglobin in a pooled plasma sample from dairy cattle suffering from foot rot.

Monoclonal antibody against membrane protein of transmissible gastroenteritis virus

Transmissible gastroenteritis virus (TGEV) is a porcine coronavirus that can cause piglet diarrhea with high mortality rates. TGEV membrane (M) protein not only plays a vital role in the process of virus assembly and budding, but also induces the production of interferon-α during infection. In this study, a monoclonal antibody (MAb) designated 7G7, against the TGEV M protein was generated by inoculating BALB/c mice with TGEV followed by hybridoma technique. Immunofluorescence assays indicated that MAb 7G7 was capable of detecting cell infection by TGEV. Virus-based ELISA demonstrated that MAb 7G7 can be used as a highly specific diagnostic reagent for TGEV.

Phages bearing affinity peptides to severe acute respiratory syndromes-associated coronavirus differentiate this virus from other viruses

BACKGROUND

Transmission of SARS-associated coronavirus (SARS-CoV) is now well controlled, nevertheless, it is important to develop effective methods to identify this virus from other pathogens.

OBJECTIVES

The purpose of this study was to identify potential ligands and develop a novel diagnostic test to SARS-CoV using phage display technology.

STUDY DESIGN

The SARS-CoV spike 1 (S1) protein containing the receptor binding region (RBD) was used as an immobilized target followed by incubation with a 12-mer phage display random peptide library. After four rounds of biopanning, 10 monoclonal phages with specific binding activity to the S1-RBD protein were obtained and subjected to binding and diagnostic assays.

RESULTS

DNA sequencing showed that two phage displayed peptides HHKTWHPPVMHL (phage-H) and SQWHPRSASYPM (phage-S) that were specific ligands to the S1 protein. Moreover, the selected phage-H and phage-S were capable of differentiating SARS-CoV from other coronaviruses in indirect enzyme-linked immunosorbent assays.

CONCLUSION

The peptides identified in this study are useful reagents for detection of SARS-CoV.

A polyclonal antibody against the C subunit of porcine aminopeptidase N expressed in Escherichia coli

The entire pig aminopeptidase N (pAPN) gene was amplified by RT-PCR using total RNA extracted from intestinal brush border membrane of a newborn piglet. The amplified products of the pAPN gene were cloned into the vector pMD18-T, generating a recombinant plasmid pMD18-T-pAPN. The C subunit of pAPN (pAPN-C) produced by PCR from the plasmid pMD18-T-pAPN was expressed in Escherichia coli using vector pET-32a with His tag. After confirming reactivity of the recombinant protein pAPN-C to antibody against native pAPN, polyclonal antibody against the recombinant protein pAPN-C was prepared in rabbit using purified protein as immunogen. In Western blot analysis, the antibody elicited by the recombinant protein pAPN-C could recognize the native pAPN. These data demonstrate that the pAPN-C recombinant protein and its polyclonal antibody can provide some basis for further receptor antagonist.

Expression, antibody generation, and biological analysis of chicken interleukin-18

The gene encoding mature chicken interleukin-18 (ChIL-18) was cloned into prokaryotic expression vector pET-30a(+), resulting in a recombinant plasmid pET-30a-ChIL-18. After pET-30a-ChIL-18 was transformed into Escherichia coli Rosseta, the expression of ChIL-18 induced by 1 mM IPTG at 37°C was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The expressed fusion protein of 26 kDa was purified with a Ni-NTA affinity column and used to generate a hyperimmune antiserum in a rabbit. The specificity and titer of anti-ChIL-18 serum were analyzed by the enzyme-linked immunosorbent assay. Western blot and immunofluorescence assays indicated that the anti-ChIL-18 antibody specifically reacted with the ChIL-18 expressed from E. coli or ChIL-18-transfected eukaryotic cells. Moreover, the renatured ChIL-18 stimulated the production of nitric oxide (NO) from macrophages via eliciting the secreting of IFN-γ from lymphocytes.

Antibody against biologically active p40 subunit of porcine interleukin-12 expressed in Escherichia coli

A truncated p40 subunit of porcine interleukin-12 (pIL-12) gene without the N-terminal signal peptide sequence was amplified by PCR and cloned into prokaryotic expression vector pGEX-6P-1. The resulting recombinant plasmid pGEX-IL12-40 was transformed into host cells BL21(DE3)pLysS, and the expression of the p40 subunit was induced using isopropyl β-D-thiogalactoside (IPTG). An anti-p40 polyclonal antibody was generated by immunizing a rabbit with the purified protein. Immunoreactivities of the p40 protein and the antibody were confirmed by immunoblotting. At the same time, a recombinant plasmid expressing the entire pIL-12 consisting of p35 and p40 genes was constructed by splicing by overlap extension (SOE)-PCR and transiently transfected into BHK-21 cells. Expression of p40 subunit on the surface of the transfected cells was identified using the anti-p40 antibody. The p40 protein and the specific antibody are biologically active and can be used as detecting reagents.