Expression, Purification, and Bioactivity of a Soluble Recombinant Ovine Interferon-tau in Escherichia Coli

INTRODUCTION

Ovine interferon-tau (oIFN-τ) is a newly discovered type I interferon. This study used biochemical techniques to transform the oIFN-τ gene into Escherichia coli to obtain the mass and soluble expression of the recombinant protein.

MATERIAL AND METHODS

First, total RNA was extracted from fresh sheep embryonic tissues with TRIzol reagent and then used as a template to reverse transcribe and amplify the mature oIFN-τ gene with RT-PCR. The amplified product was next digested with the HindIII and XhoI restriction enzymes and inserted into the pET-32a(+) vector to construct the prokaryotic expression plasmid. The corrected in-frame recombinant plasmid, pET-32a(+)-oIFN-τ, was transformed into E. coli Rosetta (DE3) competent cells. After induction with isopropyl-beta-D-thiogalactopyranoside (IPTG), the recombinant protein was detected in bacteria. Finally, the bacteria were lysed by sonication, and the recombinant protein was purified by nickel affinity chromatography and DEAE anion exchange chromatography.

RESULTS

The protein was confirmed to be oIFN-τ, which mainly existed in the soluble lysate fraction, as proven by SDS-PAGE and Western blot assays.

CONCLUSION

Purified IFN-τ exists mostly in a soluble form, and its anti-vesicular stomatitis virus (VSV) activity reached 7.08×10(6)IU/mL.

Pharmacokinetics of the recombinant ovine interferon-tau in lambs

In the current study, twenty lambs, aged 4 months, half male and half female, were classified into four groups, with five in each group. The experimental three groups of lambs were given intravenous (IV), intramuscular (IM) and subcutaneous (SC) administrations of recombinant ovine interferon-τ (roIFN-τ). The fourth group (normal control) of lambs was given normal saline injections in the same way. After administrations, blood samples were collected from the tested animals at different time points post injection, and the serum titers of roIFN-τ were measured using cytopathic effect (CPE) inhibition bioassay. The results of calculating pharmacokinetic (PK) parameters using DAS software showed that the PK characteristics of roIFN-τ through IV injection conformed to the two-compartment open model, whose half-life of distribution phases (T1/2α) was 0.33±0.034 h and the elimination half-life(T1/2β) was 5.01±0.24 h. However, the PK features of IM injection and SC injection of roIFN-τ conformed to the one compartment open model, whose Tmax were 3.11±0.26 h and 4.83±0.43 h, respectively, together with an elimination half life(T1/2β) of 9.11±0.76 h and 7. 43±0.58 h, and an absorption half-life (T1/2k(a)) of 1.13±0.31 h and 1.85±0.40 h, respectively. The bioavailability of roIFN-τ after IM administration reaches 73.57%, which is greater than that of SC administration (53.43%). These results indicate that the drug administration effect can be preferably obtained following a single dose IM administration of the roIFN-τ aqueous preparation. This study will facilitate the clinical application of roIFN-τ as a potential antiviral agent in future work.

Pharmacokinetic studies of the recombinant chicken interferon-α in broiler chickens

In this study, 24 male and female broiler chickens at 30-day-old were divided into three groups with 8 animals in each group. The animals were administered with recombinant chicken interferon-α (rChIFN-α) at a dose of 1.0 × 106 IU/kg intravenously, intramuscularly or subcutaneously, respectively. Serum samples were collected at different time points post administration, and the titers of rChIFN-α in the blood were determined by cytopathic effect inhibition assay. The results showed that the pharmacokinetic characteristics of rChIFN-α by intramuscular injection and subcutaneous injection were fitted to one compartment open model, and the Tmax was 3.21 ± 0.79 hr and 3.95 ± 0.85 hr, respectively, and the elimination half-life (T1/2) was 6.20 ± 2.77 hr and 5.03 ± 3.70 hr, respectively. In contrast, the pharmacokinetics of rChIFN-α via intravenous injection was in line with the open model of two-compartment and was eliminated in the first order, and the elimination half-life (T1/2) was 4.61 ± 0.84 hr. In addition, compared with those in the intravenous group and the subcutaneous group, the bioavailability of rChIFN-α in the intramuscular group was 82.80%. In conclusion, rChIFN-α was rapidly absorbed and slowly eliminated after intramuscular administration of single dose of rChIFN-α aqueous formulations. Thus, rChIFN-α can be used as a commonly-used therapeutic agent.