Virus load and virus shedding of SARS-CoV-2 and their impact onpatient outcomes

BACKGROUND Understanding a virus shedding patterns in body fluids/secretions is importantto determine the samples to be used for diagnosis and to formulate infectioncontrol measures.AIM To investigate the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)shedding patterns and its risk factors.METHODS All laboratory-confirmed coronavirus disease 2019 patients with completemedical records admitted to the Shenzhen Third People’s Hospital from January28, 2020 to March 8, 2020 were included. Among 145 patients (54.5% males;median age, 46.1 years), three (2.1%) died. The bronco-alveolar lavage fluid(BALF) had the highest virus load compared with the other samples. The viralload peaked at admission (3.3 × 108 copies) and sharply decreased 10 d afteradmission.RESULTS The viral load was associated with prolonged intensive care unit (ICU) duration.Patients in the ICU had significantly longer shedding time compared to those inthe wards (P < 0.0001). Age > 60 years [hazard ratio (HR) = 0.6;95% confidenceinterval (CI): 0.4-0.9] was an independent risk factor for SARS-CoV-2 shedding,while chloroquine (HR = 22.8;95%CI: 2.3-224.6) was a protective factor.CONCLUSION BALF had the highest SARS-CoV-2 load. Elderly patients had higher virus loads,which was associated with a prolonged ICU stay. Chloroquine was associatedwith shorter shedding duration and increased the chance of viral negativity.

Combination of iron flocculation and qPCR for quantitative evaluation of virus-shedding intensity of goldfish Carassius auratus infected with cyprinid herpesvirus 2 in the water and the effect of sodium chlorite powder in blocking waterborne horizontal viral transmission

Cyprinid herpesvirus 2(CyHV-2),a member of the Alloherpesviridae family belonging to the genus Cyprinivirus,was initially isolated from goldfish(Carassius auratus)and has been recently emerging as a virulent pathogen for cultured prussian carp(Carassius auratus gibelio)world-wide.In this study,a novel and effective method for concentration and quantification of live CyHV-2 virions from water was successfully established through coupling the iron flocculation with real time qPCR assay.Then,the shedding intensity of CyHV-2 in fish-tank water from artificially-challenged goldfish(25 fish/20 L)was monitored continuously for 7 days on a daily basis through quantitating viral genomic copy numbers by qPCR,and the maximum shedding level was determined to be 105 copies/L.Horizontal transmission research system was established by inoculating healthy goldfish in water spiked with serial dilution of CyHV-2 virions ranging from 107 to 103 copies/L.Our results indicated that water-borne CyHV-2 efficiently caused the infection of tested goldfish even in a concentration of 103 copies/L,and the overall transmission efficacy was not linearly correlated with the level of input virus in the fish tank.Commercial disinfectant Composite Sodium Chlorite Powder(CSCP)has been widely applied in aquaculture to control microbial infection through direct spill in the water,and its effect in inactivating the CyHV-2 infectivity remains unknown.We further determined that the EC50 of CSCP against 3.89 TCID50/mL CyHV-2 was close to 15.625μg/mL in vitro,and application of CSCP in a level as high as 60μg/mL(the safety concentration of CSCP for goldfish)couldn’t protect goldfish from CyHV-2 challenge through immersion.Thus,the disinfectant CSCP was regarded as none-effective for blocking CyHV-2 transmission in water during epidemic.Overall,our data provided quantitative data to demonstrate the shedding intensity of CyHV-2 in water,and CSCP was shown to be not effective in blocking water-borne horizontal transmission of CyHV-2 in goldfish.The virus-concentration protocol and virus-inhibition assay established here also paved the way for evaluating more commercial disinfectants in their effects in blocking water-borne horizontal transmission of CyHV-2.