Cloning and determining the nucleotide sequence and expression of human erythropoietin (h-epo) gene in E. coli cells were presented. A gene encoding for mature h-EPO was amplified from human kidney total RNA by RT-PCR using specific primers. The product was cloned into the pCR2.1 TOPO cloning vector and the nucleotide sequence containing 498 bp encoding for mature h-EPO with 166 amino acids was determined by ABI PRISM 3100 Avant Genetic Analyzer (Applied Biosysterms). To express h-EPO in E.coli cells, the h-epo gene was subcloned into the pET21 (+) vector (Novagen) by ligase reaction and was transformed into BL21 (DE3) cells. The cells harboring the recombinant plasmid were grown in liquid LB medium supplementing ampicillin (final concentration of 100g/ml) at 370C. When the OD600 nm of the culture reached 0.5, IPTG (final concentration of 0.4mM) was added. The expression of the h-EPO was analyzed by SDS-PAGE and confirmed by Western Blotting using anti-h-EPO antibody
Escherichia coli ; Human

Background: Viet Nam confirmed its first case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on 23 January 2020 among travellers from Wuhan, China, and experienced several clusters of community transmission until September. Viet Nam implemented an aggressive testing, isolation, contact tracing and quarantine strategy in response to all laboratory-confirmed cases. We report the results of SARS-CoV-2 testing during the first half of 2020 in northern Viet Nam. Methods: Between January and May 2020, 15 650 upper respiratory tract specimens were collected from 14 470 suspected cases and contacts in northern Viet Nam. All were tested for SARS-CoV-2 by real-time RT-PCR. Individuals with positive specimens were tested every three days until two tests were negative. Positive specimens from 81 individuals were cultured. Results: Among 14 470 tested individuals, 158 (1.1%) cases of SARS-CoV-2 infection were confirmed; 89 were imported and 69 were associated with community transmission. Most patients (122, 77%) had negative results after two tests, while 11 and 4 still tested positive when sampled a third and fourth time, respectively. SARS-CoV-2 was isolated from 29 of 81 specimens (36%) with a cycle threshold (Ct) value <30. Seven patients who tested positive again after testing negative had Ct values >30 and negative cultures. Conclusion Early, widespread testing for SARS-CoV-2 in northern Viet Nam identified very few cases, which, when combined with other aggressive strategies, may have dramatically contained the epidemic. We observed rapid viral clearance and very few positive results after clearance. Large-scale molecular diagnostic testing is a critical part of early detection and containment of COVID-19 in Viet Nam and will remain necessary until vaccination is widely implemented.