Virus shedding dynamics in asymptomatic and mildly symptomatic patients infected with SARS-CoV-2.

OBJECTIVES: Asymptomatic patients, together with those with mild symptoms of coronavirus disease 2019 (COVID-19), may play an important role in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. However, the dynamics of virus shedding during the various phases of the clinical course of COVID-19 remains unclear at this stage. METHODS: A total of 18 patients found to be positive for SARS-CoV-2 infection by real-time reverse transcription PCR (RT-PCR) assay and admitted to Chongqing University Central Hospital between 29 January and 5 February 2020 were enrolled into this study. Medical data, pulmonary computed tomographic (CT) scan images and RT-PCR results were periodically collected during the patients' hospital stay. All participants were actively followed up for 2 weeks after discharge. RESULTS: A total of nine (50%) asymptomatic patients and nine (50%) patients with mild symptoms of COVID-19 were identified at admission. Six patients (66.7%) who were asymptomatic at admission developed subjective symptoms during hospitalization and were recategorized as being presymptomatic. The median duration of virus shedding was 11.5, 28 and 31 days for presymptomatic, asymptomatic and mildly symptomatic patients, separately. Seven patients (38.9%) continued to shed virus after hospital discharge. During the convalescent phase, detectable antibodies to SARS-CoV-2 and RNA were simultaneously observed in five patients (27.8%). CONCLUSIONS: Long-term virus shedding was documented in patients with mild symptoms and in asymptomatic patients. Specific antibody production to SARS-CoV-2 may not guarantee virus clearance after discharge. These observations should be considered when making decisions regarding clinical and public health, and when considering strategies for the prevention and control of SARS-CoV-2 infection.

Incidence and mortality of nasopharyngeal carcinoma: interim analysis of a cluster randomized controlled screening trial (PRO-NPC-001) in southern China.

BACKGROUND: Previous mass screening studies have shown that IgA antibodies against Epstein-Barr Virus (EBV) can facilitate early detection of nasopharyngeal carcinoma (NPC), but the impact of EBV-antibody screening for NPC-specific mortality remains unknown. PATIENTS AND METHODS: A prospective, cluster randomized, controlled trial for NPC screening (PRO-NPC-001) was conducted in 3 selected towns of Zhongshan City and 13 selected towns of Sihui City in southern China beginning in 2008. Serum samples of the screening group were tested for two previously selected anti-EBV antibodies. Subjects with serological medium risk were subsequently retested annually for 3 years, and those with serological high risk were referred to otorhinolaryngologists for diagnostic check-up. An interim analysis was carried out to evaluate the primary end points of the NPC-specific mortality and the early diagnostic rate, and the secondary end point of the NPC incidence, through linkage with the database of Zhongshan City. RESULTS: Among 70 296 total subjects, 29 413 screened participants (41.8% of the total subjects) in the screening group and 50 636 in the control group, 153 (43.3 per 100 000 person-year), 62 (55.3 per 100 000 person-year) and 99 (33.1 per 100 000 person-year) NPC cases were identified. The early diagnostic rates of NPC were significantly higher in the participants (79.0%, P < 0.0001) and the screening group (45.9%, P < 0.0001) compared with the control group (20.6%). Although no differences were found between NPC-specific mortality of the screening group and the control group [relative risk (RR)= 0.82, 95% confidence interval (CI) 0.37-1.79], lower NPC-specific mortality was noticed among participants from the screening group versus the control group (RR = 0.22, 95% CI 0.09-0.49). CONCLUSION: IgA antibodies against EBV can identify high-risk population and was effective in screening for early asymptomatic NPC. Although the mortality reduction was not significant in the primary end point, we noted encouraging evidence of a mortality reduction in screening participants in this interim analysis. CLINICAL TRIAL NUMBER: NCT00941538.

Epidemics and aetiology of hand, foot and mouth disease in Xiamen, China, from 2008 to 2015.

Over the past 8 years, human enteroviruses (HEVs) have caused 27 227 cases of hand, foot and mouth disease (HFMD) in Xiamen, including 99 severe cases and six deaths. We aimed to explore the molecular epidemiology of HFMD in Xiamen to inform the development of diagnostic assays, vaccines and other interventions. From January 2009 to September 2015, 5866 samples from sentinel hospitals were tested using nested reverse transcription PCR that targeted the HEV 5' untranslated region and viral protein 1 region. Of these samples, 4290 were tested positive for HEV and the amplicons were sequenced and genotyped. Twenty-two genotypes were identified. Enterovirus 71 (EV71) and coxsackieviruses A16, A6 and A10 (CA16, CA6 and CA10) were the most common genotypes, and there were no changes in the predominant lineages of these genotypes. EV71 became the most predominant genotype every 2 years. From 2013, CA6 replaced CA16 as one of the two most common genotypes. The results demonstrate the vast diversity of HFMD pathogens, and that minor genotypes are able to replace major genotypes. We recommend carrying-out long-term monitoring of the full spectrum of HFMD pathogens, which could facilitate epidemic prediction and the development of diagnostic assays and vaccines.

Baseline antibody level may help predict the risk of active human cytomegalovirus infection in a HCMV seropositive population.

Recurrent human cytomegalovirus (HCMV) infection during pregnancy could lead to congenital HCMV infection and permanent sequelae. However, knowledge regarding the risk factors associated with recurrent HCMV infection is limited. In the present study, 1,659 paired serum samples from the natural population were collected in Guangxi Province, China, from 2003 to 2004 with a 1-year interval. The serum anti-pp150 titre was quantitatively determined using a homemade recombinant pp150-based ELISA, and the IgG titre that increased at least 4-fold was defined as a recurrent infection. The HCMV seroprevalence was above 98.6% (1,636/1,659) in Guangxi in 2003, and the infection rate during the 1-year follow-up was approximately 10% (171/1,659). The seronegative population has the highest infection risk, while the risk of recurrent infection in the seropositive population was negatively correlated with the baseline anti-pp150 titre. With a cutoff of 1:80 (the baseline anti-pp150 IgG titre), the sensitivity and specificity were 73.1% (125/171) and 85.7% (1,275/1,488) respectively, and the relative risk of infection in the high-risk group compared to the low-risk group was 10.6 (95% CI: 7.7-14.6). In conclusion, the baseline anti-pp150 IgG was negatively correlated with the risk of HCMV infection and could be an excellent predictor of HCMV infection in HCMV seropositive populations.

Drp1 is dispensable for apoptotic cytochrome c release in primed MCF10A and fibroblast cells but affects Bcl-2 antagonist-induced respiratory changes.

BACKGROUND AND PURPOSE: Dynamin-related protein 1 (Drp1) mediates mitochondrial fission and is thought to promote Bax/Bak-induced cytochrome c release during apoptosis. Conformationally active Bax, Bak and Bax/Bak-activating BH3-only proteins, such as Bim, are restrained by anti-apoptotic Bcl-2 proteins in cells that are 'primed for death'. Inhibition of Bcl-2/Bcl-xL/Bcl-w by the antagonist ABT-737 causes rapid apoptosis of primed cells. Hence, we determined whether Drp1 is required for cytochrome c release, respiratory alterations and apoptosis of cells that are already primed for death. EXPERIMENTAL APPROACH: We tested the Drp1 inhibitor mdivi-1 for inhibition of cytochrome c release in MCF10A cells primed by Bcl-2 overexpression. We measured ATP synthesis-dependent, -independent and cytochrome c-limited maximal oxygen consumption rates (OCRs) and cell death of immortalized wild-type (WT) and Drp1 knockout (KO) mouse embryonic fibroblasts (MEFs) treated with ABT-737. KEY RESULTS: Mdivi-1 failed to attenuate ABT-737-induced cytochrome c release. ABT-737 decreased maximal OCR measured in the presence of uncoupler in both WT and Drp1 KO MEF, consistent with respiratory impairment due to release of cytochrome c. However, Drp1 KO MEF were slightly less sensitive to this ABT-737-induced respiratory inhibition compared with WT, and were resistant to an initial ABT-737-induced increase in ATP synthesis-independent O2 consumption. Nevertheless, caspase-dependent cell death was not reduced. Pro-apoptotic Bax was unaltered, whereas Bak was up-regulated in Drp1 KO MEF. CONCLUSIONS AND IMPLICATIONS: The findings indicate that once fibroblast cells are primed for death, Drp1 is not required for apoptosis. However, Drp1 may contribute to ABT-737-induced respiratory changes and the kinetics of cytochrome c release.

Differential diagnosis of pandemic (H1N1) 2009 infection by detection of haemagglutinin with an enzyme-linked immunoassay.

A sensitive and convenient immunoassay that can directly differentiate pandemic (H1N1) 2009 (pH1N1) virus from seasonal influenza virus can play an important role in the clinic. In the presented study, a double-sandwich ELISA (pH1N1 ELISA), based on two monoclonal antibodies against haemagglutinin (HA) of the pH1N1 virus, was developed. After laboratory determination of the sensitivity and specificity characteristics, the performance of this assay was evaluated in a cohort of 904 patients with influenza-like illness. All seven strains of pH1N1 virus tested were positive by pH1N1 ELISA, with an average lower detection limit of 10(3.0 ± 0.4) tissue culture infective dose (TCID)(50) /mL (or 0.009 ± 0.005 HA titre). Cross-reaction of the assay with seasonal influenza virus and other common respiratory pathogens was rare. In pH1N1-infected patients, the sensitivity of the pH1N1 ELISA was 92.3% (84/91, 95% CI 84.8-96.9%), which is significantly higher than that of the BD Directigen EZ Flu A + B test (70.3%, p <0.01). The specificity of pH1N1 ELISA in seasonal influenza A patients was 100.0% (171/171, 95% CI 97.9-100.0%), similar to that in non-influenza A patients (640/642, 99.7%, 95% CI 98.9-100.0%). The positive predictive value for pH1N1 ELISA was 97.7% and the negative predictive value was 99.1% in this study population with a pH1N1 prevalence of 10.1%. In conclusion, detection of HA of pH1N1 virus by immunoassay appears to be a convenient and reliable method for the differential diagnosis of pH1N1 from other respiratory pathogens, including seasonal influenza virus.

Transfusion of plasma from a blood donor induced hepatitis E in Rhesus monkey.

BACKGROUND AND OBJECTIVES: Hepatitis E virus (HEV) infection is normally transmitted via the faeco-oral route. The possibility that the infection might be transmissible by blood has been suggested. Direct evidence of blood-borne transmission of hepatitis E infection is, however, absent. MATERIALS AND METHODS: In this report, 10 ml of plasma obtained from a healthy, but hepatitis E viraemic, blood donor was transfused to a Rhesus monkey. RESULTS: Acute hepatitis E developed following transfusion of blood from the hepatitis E viraemic donor. This was confirmed by virological, immunological, biochemical and histopathological data. CONCLUSIONS: These results, combined with other epidemiological findings previously reported, indicate that transfusion-associated hepatitis E can occur. The risk of transfusion-associated HEV infection in endemic areas should be assessed and strategies developed to reduce it.