A novel betacoronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which caused a large respiratory outbreak in Wuhan, China in December 2019, is currently spreading across many countries globally. Here, we show that a TMPRSS2expressing VeroE6 cell line is highly susceptible to SARS-CoV-2 infection, making it useful for isolating and propagating SARS-CoV-2. Our results reveal that, in common with SARS-and Middle East respiratory syndrome-CoV, SARS-CoV-2 infection is enhanced by TMPRSS2.

Multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with higher transmission potential have been emerging globally, including SARS-CoV-2 variants from the United Kingdom and South Africa. We report 4 travelers from Brazil to Japan in January 2021 infected with a novel SARS-CoV-2 variant with an additional set of mutations.

BackgroundWhile the risk of severe complications of Middle East respiratory syndrome (MERS) and its determinants have been explored in previous studies, a systematic analysis of published articles with different designs and populations has yet to be conducted. The present study aimed to systematically review the risk of death associated with MERS as well as risk factors for associated complications.MethodsPubMed and Web of Science databases were searched for clinical and epidemiological studies on confirmed cases of MERS. Eligible articles reported clinical outcomes, especially severe complications or death associated with MERS. Risks of admission to intensive care unit (ICU), mechanical ventilation and death were estimated. Subsequently, potential associations between MERS-associated death and age, sex, underlying medical conditions and study design were explored.ResultsA total of 25 eligible articles were identified. The case fatality risk ranged from 14.5 to 100%, with the pooled estimate at 39.1%. The risks of ICU admission and mechanical ventilation ranged from 44.4 to 100% and from 25.0 to 100%, with pooled estimates at 78.2 and 73.0%, respectively. These risks showed a substantial heterogeneity among the identified studies, and appeared to be the highest in case studies focusing on ICU cases. We identified older age, male sex and underlying medical conditions, including diabetes mellitus, renal disease, respiratory disease, heart disease and hypertension, as clinical predictors of death associated with MERS. In ICU case studies, the expected odds ratios (OR) of death among patients with underlying heart disease or renal disease to patients without such comorbidities were 0.6 (95% Confidence Interval (CI): 0.1, 4.3) and 0.6 (95% CI: 0.0, 2.1), respectively, while the ORs were 3.8 (95% CI: 3.4, 4.2) and 2.4 (95% CI: 2.0, 2.9), respectively, in studies with other types of designs.ConclusionsThe heterogeneity for the risk of death and severe manifestations was substantially high among the studies, and varying study designs was one of the underlying reasons for this heterogeneity. A statistical estimation of the risk of MERS death and identification of risk factors must be conducted, particularly considering the study design and potential biases associated with case detection and diagnosis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12889-016-3881-4) contains supplementary material, which is available to authorized users.

We present two cases of imported Zika fever to Japan, in travellers returning from French Polynesia, where an outbreak due to Zika virus (ZIKV) is ongoing since week 41 of 2013. This report serves to raise awareness among healthcare professionals, that the differential diagnosis of febrile and subfebrile patients with rash should include ZIKV infection, especially in patients returning from areas affected by this virus.

Some patients who recover from COVID-19 have prolonged symptoms such as dyspnea, fatigue, cough, and dysosmia for longer than 120 days after symptom onset. In addition, some patients who recovered from COVID-19 reported hair loss a few months after the onset of the disease. Alopecia is a late-onset symptom of COVID-19. The cause of alopecia is unknown, however, androgenic alopecia and telogen effluvium are possible causes.

Macrolide or fluoroquinolone-resistant Mycoplasma genitalium is spreading worldwide. We aimed to determine the influence of single nucleotide polymorphisms (SNPs) in the quinolone resistance determining regions (QRDR) of parC and gyrA in cultured M. genitalium strains. In addition, we examined the prevalence of macrolide- and fluoroquinolone resistance mediating mutations in specimens collected from Japanese male patients with urethritis in two time-periods between 2005–2009 and 2010–2017, respectively, by sequencing the QRDR of parC and gyrA and domain V of the 23S rRNA gene. The minimum inhibitory concentrations (MIC) of moxifloxacin, sitafloxacin, ciprofloxacin, levofloxacin, doxycycline, minocycline, azithromycin and clarithromycin were determined in 23 M. genitalium strains. Three cultured strains had elevated MICs for moxifloxacin at 16, 4 and 2 mg/L and had SNPs with the amino-acid change Ser83→Ile in ParC (p<0.001) and 3 kinds of SNPs with amino-acid changes Asp99→Asn, Gly93→Cys and Met95→Ile in GyrA, respectively. Among a total of 148 M. genitalium positive urine specimens, the prevalence of A2058G and A2059G SNPs in the 23S rRNA gene and any SNPs in ParC increased from 4.8% and 22.6% in 2005–2009 to 42.2% and 53.1% in 2010–2017, respectively. If M. genitalium is considered multi-drug resistant in clinical specimens carrying SNPs in the 23S rRNA gene and Ser83→Ile in ParC, the prevalence of multi-drug resistance is 12.5% in 2010–2017 in Japan. In conclusion, the SNP resulting in Ser83→Ile in ParC is closely related to moxifloxacin resistance even though other factors may also affect treatment outcomes by moxifloxacin. The prevalence of circulating multi-drug resistant M. genitalium strains with macrolide- and fluoroquinolone-resistance is dramatically increasing in Japan.

After 70 years with no confirmed autochthonous cases of dengue fever in Japan, 19 cases were reported during August–September 2014. Dengue virus serotype 1 was detected in 18 patients. Phylogenetic analysis of the envelope protein genome sequence from 3 patients revealed 100% identity with the strain from the first patient (2014) in Japan.

While there are various attempts to administer COVID-19-convalescent plasmas to SARS-CoV-2-infected patients, neither appropriate approach nor clinical utility has been established. We examined the presence and temporal changes of the neutralizing activity of IgG fractions from 43 COVID-19-convalescent plasmas using cell-based assays with multiple endpoints. IgG fractions from 27 cases (62.8%) had significant neutralizing activity and moderately to potently inhibited SARS-CoV-2 infection in cell-based assays; however, no detectable neutralizing activity was found in 16 cases (37.2%). Approximately half of the patients (~ 41%), who had significant neutralizing activity, lost the neutralization activity within ~ 1 month. Despite the rapid decline of neutralizing activity in plasmas, good amounts of SARS-CoV-2-S1-binding antibodies were persistently seen. The longer exposure of COVID-19 patients to greater amounts of SARS-CoV-2 elicits potent immune response to SARS-CoV-2, producing greater neutralization activity and SARS-CoV-2-S1-binding antibody amounts. The dilution of highly-neutralizing plasmas with poorly-neutralizing plasmas relatively readily reduced neutralizing activity. The presence of good amounts of SARS-CoV-2-S1-binding antibodies does not serve as a surrogate ensuring the presence of good neutralizing activity. In selecting good COVID-19-convalescent plasmas, quantification of neutralizing activity in each plasma sample before collection and use is required.