Acute tubulointerstitial nephritis with or without uveitis: a novel form of post-acute COVID-19 syndrome in children (preprint)

Background COVID-19 is a complex multisystem disease, frequently associated with kidney injury. Since the beginning of the COVID-19 pandemic, we observed a striking increase in the incidence of acute tubulointerstitial nephritis (aTIN) without or with uveitis (TINUs) among children. This prompted us to examine whether SARS-CoV-2 might be the underlying trigger. Methods We conducted a French nationwide retrospective cohort study. We included all consecutive children diagnosed with aTIN or TINUs of undetermined cause between April-2020 and March-2021. SARS-CoV-2 antibody responses were tested by a luciferase immunoprecipitation system and compared to age-matched controls. Immunohistochemistry, immunofluorescence and molecular microbiology analyses were performed on kidney biopsies. Results Forty-eight children were included with a median age at diagnosis of 14.7 years (9.4-17.6). aTIN and TINUs incidence rates increased 3-fold and 12-fold, respectively, compared to pre-pandemic years. All patients had impaired kidney function with a median eGFR of 31.9 ml/min/1.73m2 at diagnosis. Kidney biopsies showed lesions of acute tubulointerstitial nephritis and 25% of patients had fibrosis. No patient had concomitant acute COVID-19. All 16 children tested had high anti-N IgG titers and one had anti-S IgGs. Next-generation sequencing failed to detect any infectious agents in kidney biopsies. However, SARS-CoV-2 RNA was detected by PCR in two kidney samples supporting a potential direct link between SARS-CoV-2 and aTIN/TINUs. Conclusions We describe a novel form of post-acute COVID-19 syndrome in children, unique in its exclusive kidney and eye involvement, and its distinctive anti-SARS-CoV-2 N+/S- serological profile. Our results support a causal association linking SARS-CoV-2 infection to this newly-reported burst of renal/eye inflammation.

SARS-CoV-2-Related Bat Virus in Human Relevant Models Sheds Light on the Proximal Origin of COVID-19 (preprint)

Bat sarbecovirus BANAL-236 is highly related to SARS-CoV-2 and infects human cells, albeit lacking the furin cleavage site in its spike protein. To inform on the origin of SARS-CoV-2, we evaluated the clinical, epidemiological and evolutionary consequences of a potential BANAL-236 spillover into humans using animal models. The virus replicates efficiently and pauci-symptomatically in humanized mice and in macaques, where its tropism is enteric, strongly differing from that of SARS-CoV-2. BANAL-236 infection leads to protection against superinfection by a more virulent strain like Wuhan SARS-CoV-2. Yet we found no evidence of antibodies recognizing bat sarbecoviruses in populations highly exposed to bats, indicating that such infections, if they occur, are rare. Six passages in mice or in human intestinal cells, mimicking putative early spillover events, selected adaptive mutations without appearance of a furin cleavage site and not change in virulence. We thus conclude that the hypothesis of the SARS-CoV-2 pandemic being preceded by silent circulation in humans of BANAL-236-like strains leading to the acquisition of a furin cleavage site is unlikely. Our studies suggest that a specific search for a furin cleavage site in sarbecoviruses in the wild should be pursued to understand the origin of the SARS-CoV-2 pandemics.

Coronaviruses with a SARS-CoV-2-like receptor-binding domain allowing ACE2-mediated entry into human cells isolated from bats of Indochinese peninsula (preprint)

The animal reservoir of SARS-CoV-2 is unknown despite reports of various SARS-CoV-2-related viruses in Asian Rhinolophus bats, including the closest virus from R. affinis, RaTG13. Several studies have suggested the involvement of pangolin coronaviruses in SARS-CoV-2 emergence. SARS-CoV-2 presents a mosaic genome, to which different progenitors contribute. The spike sequence determines the binding affinity and accessibility of its receptor-binding domain (RBD) to the cellular angiotensin-converting enzyme 2 (ACE2) receptor and is responsible for host range. SARS-CoV-2 progenitor bat viruses genetically close to SARS-CoV-2 and able to enter human cells through a human ACE2 pathway have not yet been identified, though they would be key in understanding the origin of the epidemics. Here we show that such viruses indeed circulate in cave bats living in the limestone karstic terrain in North Laos, within the Indochinese peninsula. We found that the RBDs of these viruses differ from that of SARS-CoV-2 by only one or two residues, bind as efficiently to the hACE2 protein as the SARS-CoV-2 Wuhan strain isolated in early human cases, and mediate hACE2-dependent entry into human cells, which is inhibited by antibodies neutralizing SARS-CoV-2. None of these bat viruses harbors a furin cleavage site in the spike. Our findings therefore indicate that bat-borne SARS-CoV-2-like viruses potentially infectious for humans circulate in Rhinolophus spp. in the Indochinese peninsula.

Low Seroprevalence of COVID-19 in Lao PDR, Late 2020 (preprint)

Background: Lao PDR has low reported COVID-19 cases but it is unclear whether this masks silent transmission. A nationwide seroprevalence study was done between August and September 2020 to determine SARS-CoV-2 exposure.Methods: Participants were from the general community/healthcare workers in five provinces. Bat/wildlife contacts were from Vientiane province. ELISAs detected anti-Nucleoprotein (N; n=3173 tested) and anti-Spike (S; n=1417 tested) SARS-CoV-2 antibodies. Double-positive samples were checked by IgM/IgG rapid tests. Positive controls were confirmed COVID-19 cases and negative controls were pre-COVID-19 samples.Findings: In pre-COVID-19 samples, 14/265 (5·3%, [95% CI=3·1-8·7%]) were anti-N antibody single-positive and 3/265 (1·1% [0·3-3·5%]) were anti-S antibody single positive. None were anti-N and anti-S antibody double positive. Anti-N and anti-S antibodies were detected in 131/2417 (5·4% [4·5-6·3%]) and 19/1061 (1·8% [1·1-2·8%]) of the general population, 13/666 (2·0% [1·1-3·3%]) and 4/282 (1·4% [0·5-3·7%]) of healthcare workers and 15/74 (20·3% [12·6-31·0%]) and 5/74 (6·8% [2·8-15·3%]) of bat/wildlife contacts. Only 2/3173 (0·1% [0·02-0·3%]) were double positive for anti-N and anti-S antibodies (rapid test negative).Interpretation: We find no evidence for significant circulation of SARS-CoV-2 in Lao PDR during or before September 2020. This likely results from decisive measures taken by the government early in the pandemic, social behavior, and low population density. High anti-N antibodies/low anti-S antibodies in bat/wildlife contacts may indicate exposure to cross-reactive animal coronaviruses with threat of emerging novel viruses.Funding: Core; Agence Française de Développement. Additional support; Institut Pasteur du Laos, Institute Pasteur, Paris and Luxembourg Ministry of Foreign and European Affairs (“PaReCIDS II”). Declaration of Interests: The authors have no conflict of interest to declare.Ethics Approval Statement: The study protocol was approved by all participating institutes and by the Lao National Ethics Committee for Health Research (NECHR) (Ref #052/2020).

Prior infection by seasonal coronaviruses does not prevent SARS-CoV-2 infection and associated Multisystem Inflammatory Syndrome in children (preprint)

Background: Children have a lower rate of COVID-19, potentially related to cross-protective immunity conferred by seasonal coronaviruses (HCoVs). We tested if prior infections with seasonal coronaviruses impacted SARS-CoV-2 infections and related Multisystem Inflammatory Syndrome (MIS). Methods: This cross-sectional observational study in Paris hospitals enrolled 739 pauci or asymptomatic children (HOS group) plus 36 children with suspected MIS (MIS group). Prevalence, antigen specificity and neutralizing capability of SARS-CoV-2 antibodies were tested. Antibody frequency and titres against Nucleocapsid (N) and Spike (S) of the four seasonal coronaviruses (NL63, HKU1, 229E, OC43) were measured in a subset of seropositive patients (54 SARS-CoV-2 (HOS-P subgroup) and 15 MIS (MIS-P subgroup)), and in 118 matched SARS-CoV-2 seronegative patients (CTL subgroup). Findings: SARS-CoV-2 mean prevalence rate in HOSP children was 11.7% from April 1 to June 1. Neutralizing antibodies were found in 55.6% of seropositive children, and their relative frequency increased with time (up to 100 % by mid-May). A majority of MIS children (25/36) were SARS-CoV-2 seropositive, of which all tested (n=15) had neutralizing antibodies. On average, seropositive MIS children had higher N and S1 SARS-CoV-2 titres as compared to HOS children. Patients from HOS-P, MIS-P, and CTL subgroups had a similar prevalence of antibodies against the four seasonal HCoVs (66.9 -100%). The level of anti-SARS-CoV-2 antibodies was not significantly different in children who had prior seasonal coronavirus infection. Interpretation: Prior infection with HCoVs does not prevent SARS-CoV-2 infection and related MIS in children. Children develop neutralizing antibodies after SARS-CoV-2 infection.

SARS-CoV-2 serological analysis of COVID-19 hospitalized patients, pauci-symptomatic individuals and blood donors. (preprint)

It is of paramount importance to evaluate the prevalence of both asymptomatic and symptomatic cases of SARS-CoV-2 infection and their antibody response profile. Here, we performed a pilot study to assess the levels of anti-SARS-CoV-2 antibodies in samples taken from 491 pre- epidemic individuals, 51 patients from Hopital Bichat (Paris), 209 pauci-symptomatic individuals in the French Oise region and 200 contemporary Oise blood donors. Two in-house ELISA assays, that recognize the full-length nucleoprotein (N) or trimeric Spike (S) ectodomain were implemented. We also developed two novel assays: the S-Flow assay, which is based on the recognition of S at the cell surface by flow-cytometry, and the LIPS assay that recognizes diverse antigens (including S1 or N C- terminal domain) by immunoprecipitation. Overall, the results obtained with the four assays were similar, with differences in sensitivity that can be attributed to the technique and the antigen in use. High antibody titers were associated with neutralisation activity, assessed using infectious SARS-CoV- 2 or lentiviral-S pseudotypes. In hospitalized patients, seroconversion and neutralisation occurred on 5-14 days post symptom onset, confirming previous studies. Seropositivity was detected in 29% of pauci-symptomatic individuals within 15 days post-symptoms and 3 % of blood of healthy donors collected in the area of a cluster of COVID cases. Altogether, our assays allow for a broad evaluation of SARS-CoV2 seroprevalence and antibody profiling in different population subsets.

Cluster of COVID-19 in northern France: A retrospective closed cohort study (preprint)

Background: The Oise department in France has been heavily affected by COVID-19 in early 2020. Methods: Between 30 March and 4 April 2020, we conducted a retrospective closed cohort study among pupils, their parents and siblings, as well as teachers and non-teaching staff of a high-school located in Oise. Participants completed a questionnaire that covered history of fever and/or respiratory symptoms since 13 January 2020 and had blood tested for the presence of anti-SARS-CoV-2 antibodies. The infection attack rate (IAR) was defined as the proportion of participants with confirmed SARS-CoV-2 infection based on antibody detection. Blood samples from two blood donor centres collected between 23 and 27 March 2020 in the Oise department were also tested for presence of anti-SARS-CoV-2 antibodies. Findings: Of the 661 participants (median age: 37 years), 171 participants had anti-SARS-CoV-2 antibodies. The overall IAR was 25.9% (95% confidence interval (CI) = 22.6-29.4), and the infection fatality rate was 0% (one-sided 97.5% CI = 0-2.1). Nine of the ten participants hospitalised since mid-January were in the infected group, giving a hospitalisation rate of 5.3% (95% CI = 2.4-9.8). Anosmia and ageusia had high positive predictive values for SARS-CoV-2 infection (84.7% and 88.1%, respectively). Smokers had a lower IAR compared to non-smokers (7.2% versus 28.0%, P <0.001). The proportion of infected individuals who had no symptoms during the study period was 17.0% (95% CI = 11.2-23.4). The proportion of donors with anti-SARS-CoV-2 antibodies in two nearby blood banks of the Oise department was 3.0% (95% CI = 1.1-6.4). Interpretation: The relatively low IAR observed in an area where SARS-CoV-2 actively circulated weeks before confinement measures indicates that establishing herd immunity will take time, and that lifting these measures in France will be long and complex.

Absence of SARS-CoV-2 infection in cats and dogs in close contact with a cluster of COVID-19 patients in a veterinary campus (preprint)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which originated in Wuhan, China, in 2019, is responsible for the COVID-19 pandemic. It is now accepted that the wild fauna, probably bats, constitute the initial reservoir of the virus, but little is known about the role pets can play in the spread of the disease in human communities, knowing the ability of SARS-CoV-2 to infect some domestic animals. We tested 21 domestic pets (9 cats and 12 dogs) living in close contact with their owners (belonging to a veterinary community of 20 students) in which two students tested positive for COVID-19 and several others (n = 11/18) consecutively showed clinical signs (fever, cough, anosmia, etc.) compatible with COVID-19 infection. Although a few pets presented many clinical signs indicative for a coronavirus infection, no animal tested positive for SARS-CoV-2 by RT-PCR and no antibodies against SARS-CoV-2 were detectable in their blood using an immunoprecipitation assay. These original data can serve a better evaluation of the host range of SARS-CoV-2 in natural environment exposure conditions.