The kinetics of viral load and antibodies to SARS-CoV-2

Abstract

Objectives To understand persistence of the virus in body fluids and immune response of infected host to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), an agent of coronavirus disease 2019 (COVID-19). Methods We determined the kinetics of viral load in several body fluids through real time reverse transcription polymerase chain reaction (rRT-PCR), serum antibodies of IgA, IgG and IgM by enzyme linked immunosorbent assay (ELISA), and neutralizing antibodies by microneutralization assay in 35 COVID-19 cases from two hospitals in Guangdong, China. Results We found higher viral loads and prolonged shedding of virus RNA in severe cases of COVID-19 in nasopharyngeal (1.3×10 6 vs 6.4×10 4 , p<0.05; 7∼8w) and throat (6.9×10 6 vs 2.9×10 5 , p<0.05; 4∼5w), while comparable in sputum samples (5.5×10 6 vs 0.9×10 6 , p<0.05; 4∼5w). Viraemia was rarely detected (2.8%, n=1/35). We detected early seroconversion of IgA and IgG at 1 st week after illness onset (day 5, 5.7%, n=2/35). Neutralizing antibodies were produced in the second week, and observed in all 35 included cases after 3 rd week illness onset. The levels of neutralizing antibodies correlated with IgG (r s =0.85, p<0.05; kappa=0.85) and IgA (r s =0.64, p<0.05; kappa=0.61) in severe, but not mild cases (IgG, r s =0.42, kappa=0.33; IgA, r s =0.32, kappa=0.22). No correlation with IgM in either severe (r s =0.17, kappa=0.06) or mild cases (r s =0.27, kappa=0.15) was found. Conclusions We revealed a prolonged shedding of virus RNA in upper respiratory tract, and evaluated the consistency production of IgG, IgA, IgM and neutralizing antibodies in COVID-19 cases.

COVID-19–associated Nephropathy Includes Tubular Necrosis and Capillary Congestion, with Evidence of SARS-CoV-2 in the Nephron

“…We have no information about the viremia in our cohort. Of note, positive SARS-CoV-2 viremia has been reported as detectable in less than 40% of patients with COVID-19 pneumonia 52,53 . We provide a detailed clinical and biological description of all cases, thereby allowing correlations and comparisons to previous reports (summarized in Supplementary Table 4).…”

Prenatal Biochemical and Ultrasound Markers in COVID-19 Pregnant Patients: A Prospective Case-Control Study

“…Only women with last menstruation at most one month later than the date of the first reported case of COVID-19 infection in Piedmont (22 February 2020) were considered eligible for inclusion in the study, so as to exclude the possibility of COVID-19 seroconversion before pregnancy ( Figure 1). The duration of SARS-CoV-2 virus shedding varies up to 6-8 weeks in upper respiratory tract samples and 5 weeks in feces [14]. This strict recruitment criterion allowed us to define seropositivity as a seroconversion that had occurred during pregnancy.…”

Antibody Responses in COVID-19: A Review

“…In contrast, Zhang et al described that the production of IgM and IgG was delayed in the critical group and reached the peak at 1-month POS (76). Several studies, including an aforementioned meta-analysis, suggest that seroconversion of both IgM and IgG occurs at around 12 days POS with extensive variation, but does not shed any light towards severity (66), underlying the importance of further studies (66,(74)(75)(76)(77)(78). This evidence on the first phase of antibody response in COVID-19 resembles that for other coronaviruses.…”