ABSTRACT
The current study was initiated when our specific pathogen-free laboratory toms developed unexpectedly high levels of cross-reactive antibodies to human SARS-CoV-2 (SCoV2) receptor binding domain (RBD) upon mating with feline coronavirus (FCoV)-positive queens. Multi-sequence alignment analyses of SCoV2 Wuhan RBD and four strains each from FCoV serotypes 1 and 2 (FCoV1, FCoV2) demonstrated amino acid sequence identity of 11.5% and similarity of 31.8% with FCoV1 RBD, as well as 12.2% identity and 36.5% similarity for FCoV2 RBD. The sera from all three toms and three mated queens cross-reacted with SCoV2 RBD and reacted with FCoV1 RBD and FCoV2 spike-2, nucleocapsid, and membrane proteins of FCoV2 whole-virus, but not with FCoV2 RBD. Additionally, the plasma from all six FCoV2-inoculated laboratory cats reacted with FCoV2 and SCoV2 RBDs, but not with FCoV1 RBD. In another study, eight group-housed laboratory cats from a different lineage had a range of serum cross-reactivity to SCoV2 RBD even 15 months later. Such cross-reactivity was also observed in FCoV1-positive group-housed pet cats. The SCoV2 RBD at a high non-toxic dose and FCoV2 RBD at a 60-400-fold lower dose blocked the in vitro FCoV2 infection of the feline cells, demonstrating their close structural conformations essential as vaccine immunogens. Furthermore, such cross-reactivity to SCoV2 RBD was also detected by the peripheral blood mononuclear cells of both transient and chronically FCoV1-infected cats. Overall, the cross-reactivity with SCoV2 RBD by the sera from both serotypes of FCoV-infected cats also suggests that the cross-reactive epitope(s) on FCoV1 and FCoV2 RBDs may be similar to those of SCoV2 RBD and provides essential insights to developing a pan-CoV vaccine. Author SummaryTo date, there are no reports on the sera from feline coronavirus (FCoV)-infected cats cross-reacting with either SARS-CoV-1 or SARS-CoV2 (SCoV2) receptor binding domains (RBDs). This report describes the presence of cross-reactive antibodies to SCoV2 RBD in the sera of FCoV-infected laboratory cats, even though SCoV2 RBD and each FCoV serotype (FCoV1, FCoV2) RBD had minimal sequence similarity. However, this observation of serum cross-reactivity to SCoV2 RBD was confirmed by more stringent antibody-based assays and viral assays. Furthermore, both serotypes of FCoV-infected cats, including FCoV1-infected pet cats, produced the cross-reactive antibodies, and such cross-reactivity to SCoV2 RBD was also detected, most likely, by the T cells in peripheral blood mononuclear cells of both transient and chronically FCoV1-infected cats. Since SCoV2 RBD is essential component for current vaccines against COVID-19 disease, our findings should provide essential insights to developing a pan-coronavirus vaccine that induces full-scale immunity to completely prevent SCoV2 infection in humans and pet animals.
ABSTRACT
We screened 65 longitudinally-collected nasal swab samples from 31 children aged 0-16 years who were positive for SARS-CoV-2 omicron BA.1. By day 7 after onset of symptoms 48% of children remained positive by rapid antigen test. In a sample subset we found 100% correlation between antigen test results and virus culture.
ABSTRACT
Between February 2019 and March 2021, 388 dried blood spot samples were obtained from 257 children <30 months of age who were part of a longitudinal maternal/infant cohort in Haiti. Among the children followed, 16.7% became seropositive; sampling date was the only covariate associated with the hazard of seroconversion.
ABSTRACT
BackgroundSARS-CoV-2 Delta variant has caused a dramatic resurgence in infections in the United Sates, raising questions regarding potential transmissibility among vaccinated individuals. MethodsBetween October 2020 and July 2021, we sequenced 4,439 SARS-CoV-2 full genomes, 23% of all known infections in Alachua County, Florida, including 109 vaccine breakthrough cases. Univariate and multivariate regression analyses were conducted to evaluate associations between viral load (VL) level and patient characteristics. Contact tracing and phylogenetic analysis were used to investigate direct transmissions involving vaccinated individuals. ResultsThe majority of breakthrough sequences with lineage assignment were classified as Delta variants (74.6%) and occurred, on average, about three months (104 {+/-} 57.5 days) after full vaccination, at the same time (June-July 2021) of Delta variant exponential spread within the county. Six Delta variant transmission pairs between fully vaccinated individuals were identified through contact tracing, three of which were confirmed by phylogenetic analysis. Delta breakthroughs exhibited broad VL values during acute infection (IQR 1.2 - 8.64 Log copies/ml), on average 38% lower than matched unvaccinated patients (3.29 - 10.81 Log copies/ml, p<0.00001). Nevertheless, 49-50% of all breakthroughs, and 56-60% of Delta-infected breakthroughs exhibited VL above the transmissibility threshold (4 Log copies/ml) irrespective of time post vaccination. ConclusionsDelta infection transmissibility and general VL patterns in vaccinated individuals suggest limited levels of sterilizing immunity that need to be considered by public health policies. In particular, ongoing evaluation of vaccine boosters should address whether extra vaccine doses might curb breakthrough contribution to epidemic spread.
ABSTRACT
The emergence of SARS-CoV-2 variants of concern (VOC) has raised questions regarding the extent of protection of currently implemented vaccines. Ten "vaccination breakthrough" infections were identified in Alachua County, Florida, among individuals fully vaccinated with the BNT162b2 mRNA vaccine as a result of social or household transmission. Eight individuals presented mild symptoms in the absence of infection with other common respiratory viruses, confirmed using viral genetic sequencing. SARS-CoV-2 genomes were successfully generated for five of the vaccine breakthroughs and 399 individuals in the surrounding area and were included for reference-based phylogenetic investigation. These five individuals were characterized by infection with both VOCs and low-frequency variants present within the surrounding population. Mutations, in the Spike glycoprotein, were consistent with their respective circulating lineages. However, we detected an additional mutation in Spikes N-terminal domain of a B.1.1.7 strain, present at low-frequency ([~]1%) in the unvaccinated population, potentially affecting proteins stability and functionality. The findings highlight the critical need for continued testing and monitoring of infection among individuals regardless of vaccination status.
ABSTRACT
We used a Sioutas personal cascade impactor sampler (PCIS) to screen for SARS-CoV-2 in a car driven by a COVID-19 patient. SARS-CoV-2 was detectable at all PCIS stages by PCR and was cultured from the section of the sampler collecting particles in the 0.25 to 0.50 {square}m size range.
ABSTRACT
BackgroundThere currently is substantial controversy about the role played by SARS-CoV-2 in aerosols in disease transmission, due in part to detections of viral RNA but failures to isolate viable virus from clinically generated aerosols. MethodsAir samples were collected in the room of two COVID-19 patients, one of whom had an active respiratory infection with a nasopharyngeal (NP) swab positive for SARS-CoV-2 by RT-qPCR. By using VIVAS air samplers that operate on a gentle water-vapor condensation principle, material was collected from room air and subjected to RT-qPCR and virus culture. The genomes of the SARS-CoV-2 collected from the air and of virus isolated in cell culture from air sampling and from a NP swab from a newly admitted patient in the room were sequenced. FindingsViable virus was isolated from air samples collected 2 to 4.8m away from the patients. The genome sequence of the SARS-CoV-2 strain isolated from the material collected by the air samplers was identical to that isolated from the NP swab from the patient with an active infection. Estimates of viable viral concentrations ranged from 6 to 74 TCID50 units/L of air. InterpretationPatients with respiratory manifestations of COVID-19 produce aerosols in the absence of aerosol-generating procedures that contain viable SARS-CoV-2, and these aerosols may serve as a source of transmission of the virus. FundingPartly funded by Grant No. 2030844 from the National Science Foundation and by award 1R43ES030649 from the National Institute of Environmental Health Sciences of the National Institutes of Health, and by funds made available by the University of Florida Emerging Pathogens Institute and the Office of the Dean, University of Florida College of Medicine. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSVarious studies report detection of SARS-CoV-2 in material collected by air samplers positioned in clinics and in some public spaces. For those studies, detection of SARS-CoV-2 has been by indirect means; instead of virus isolation, the presence of the virus in material collected by air samplers has been through RT-PCR detection of SARS-CoV-2 RNA. However, questions have been raised about the clinical significance of detection of SARS-CoV-2 RNA, particularly as airborne viruses are often inactivated by exposure to UV light, drying, and other environmental conditions, and inactivated SARS-CoV-2 cannot cause COVID-19. Added value of this studyOur virus isolation work provides direct evidence that SARS-CoV-2 in aerosols can be viable and thus pose a risk for transmission of the virus. Furthermore, we show a clear progression of virus-induced cytopathic effects in cell culture, and demonstrate that the recovered virus can be serially propagated. Moreover, we demonstrate an essential link: the viruses we isolated in material collected in four air sampling runs and the virus in a newly admitted symptomatic patient in the room were identical. These findings strengthen the notion that airborne transmission of viable SARS-CoV-2 is likely and plays a critical role in the spread of COVID-19. Implications of all the available evidenceScientific information on the mode of transmission should guide best practices Current best practices for limiting the spread of COVID-19. Transmission secondary to aerosols, without the need for an aerosol-generating procedure, especially in closed spaces and gatherings, has been epidemiologically linked to exposures and outbreaks. For aerosol-based transmission, measures such as physical distancing by 6 feet would not be helpful in an indoor setting and would provide a false-sense of security. With the current surges of cases, to help stem the COVID-19 pandemic, clear guidance on control measures against SARS-CoV-2 aerosols are needed.
ABSTRACT
Zika virus (ZIKV) circulates as two separate lineages, with significant genetic variability between strains. Strain-dependent activity has been reported for dengue virus, herpes simplex virus and influenza. Strain-dependent activity of subject specimens to a virus could be an impediment to serological diagnosis and vaccine development. In order to determine whether ZIKV exhibits strain-dependent activity when exposed to antibodies, we measured the neutralizing properties of polyclonal serum and three monoclonal antibodies (ZKA185, 753(3)C10, and 4G2) against three strains of ZIKV (MR-766, PRVABC59, and R103454). Here, MR-766 was inhibited almost 60% less by ZKA185 than PRVABC59 and R103454 (p = 0.008). ZKA185 enhanced dengue 4 infection up to 50% (p = 0.0058). PRVABC59 was not inhibited by mAb 753(3)C10 while MR-766 and R103453 were inhibited up to 90% (p = 0.04 and 0.036, respectively). Patient serum, regardless of exposure history, neutralized MR-766 ~30%-40% better than PRVABC56 or R103454 (p = 0.005-0.00007). The most troubling finding was the significant neutralization of MR-766 by patients with no ZIKV exposure. We also evaluated ZIKV antibody cross reactivity with various flaviviruses and found that more patients developed cross-reactive antibodies to Japanese encephalitis virus than the dengue viruses. The data here show that serological diagnosis of ZIKV is complicated and that qualitative neutralization assays cannot discriminate between flaviviruses.
