Novel coronavirus mutations: Vaccine development and challenges.

The ongoing global pandemic of novel coronavirus pneumonia (COVID-19) caused by the SARS-CoV-2 has a significant impact on global health and economy system. In this context, there have been some landmark advances in vaccine development. Over 100 new coronavirus vaccine candidates have been approved for clinical trials, with ten WHO-approved vaccines including four inactivated virus vaccines, two mRNA vaccines, three recombinant viral vectored vaccines and one protein subunit vaccine on the "Emergency Use Listing". Although the SARS-CoV-2 has an internal proofreading mechanism, there have been a number of mutations emerged in the pandemic affecting its transmissibility, pathogenicity and immunogenicity. Of these, mutations in the spike (S) protein and the resultant mutant variants have posed new challenges for vaccine development and application. In this review article, we present an overview of vaccine development, the prevalence of new coronavirus variants and their impact on protective efficacy of existing vaccines and possible immunization strategies coping with the viral mutation and diversity.

CLINICAL APPLICATION OF RT-PCR IN TUBERCULOSIS DNA DETECTION COMBINED WITH TB-IGRA IN THE DIAGNOSIS OF SPUTUM SMEAR-NEGATIVE PULMONARY TUBERCULOSIS.

The aim was to investigate detection of pulmonary alveolar lavage fluid tuberculosis DNA by real-time fluorescent polymerase chain reaction (RT-PCR) combined with clinical application of the sputum smear-negative pulmonary tuberculosis diagnosis with TB interferon-γ release assay (TB-IGRA). From October 2014 to October 2015, 632 outpatients and inpatients treated in our hospital were randomly selected, of which 459 patients as the research group managed with RT-PCR detection combined with TB-IGRA and 173 patients as the control group undergoing electronic bronchoscopy alveolar lavage fluid detection, with detection results statistically evaluated. The positive rate in the research group was 96.51%, i.e. significantly higher than that in the control group (66.47%), yielding a statistically significant difference (χ2=109.68, p=0.00). The true positive rate was 97.7% in the research group and 67.92% in the control group; the true positive rate was significantly higher in the research group patients as compared with the control group, yielding a statistically significant difference (χ2=112.04, p=0.00). The sensitivity and specificity, as well as Youden index were significantly higher in the research group as compared with the control group. In conclusion, TB DNA detection by RT-PCR combined with TB-IGRA is a very good method of diagnosing tuberculosis, and it can be implemented in clinical diagnosis of pulmonary tuberculosis.

Changes in Serum Neutralizing Antibodies Levels During Convalescence of COVID-19 Patients.

Detection of serum-specific SARS-CoV-2 antibody has become a complementary means for the identification of coronavirus disease 2019 (COVID-19). As we already know, the neutralizing antibody titers in patients with COVID-19 decrease during the course of time after convalescence, whereas the duration of antibody responses in the convalescent patients has not been defined clearly. In the current study, we collected 148 serum samples from 37 confirmed COVID-19 cases with different disease severities. The neutralizing antibodies (Nabs), IgM and IgG against COVID-19 were determined by CLIA Microparticle and microneutralization assay, respectively. The time duration of serum titers of SARS-CoV-2 antibodies were recorded. Our results indicate that IgG (94.44%) and Nabs (89.19%) can be detected at low levels within 190-266 days of disease onset. The findings can advance knowledge regarding the antibody detection results for COVID-19 patients and provide a method for evaluating the immune response after vaccination.