The CRISPR-Cas9 system is a powerful tool for genome editing, which allows the precise modification of specific DNA sequences. Many efforts are underway to use the CRISPR-Cas9 system to therapeutically correct human genetic diseases [1][2][3][4][5][6] . The most widely used orthologs of Cas9 are derived from Staphylococcus aureus and Streptococcus pyogenes 5,7 . Given that these two bacterial species infect the human population at high frequencies 8,9 , we hypothesized that humans may harbor preexisting adaptive immune responses to the Cas9 orthologs derived from these bacterial species, SaCas9 (S. aureus) and SpCas9 (S. pyogenes). By probing human serum for the presence of anti-Cas9 antibodies using an enzyme-linked immunosorbent assay, we detected antibodies against both SaCas9 and SpCas9 in 78% and 58% of donors, respectively. We also found anti-SaCas9 T cells in 78% and anti-SpCas9 T cells in 67% of donors, which demonstrates a high prevalence of antigen-specific T cells against both orthologs. We confirmed that these T cells were Cas9-specific by demonstrating a Cas9-specific cytokine response following isolation, Reprints and permissions information is available at www.nature.com/reprints.

The CRISPR-Cas9 system has proven to be a powerful tool for genome editing, allowing for the precise modification of specific DNA sequences within a cell. Many efforts are currently underway to use the CRISPR-Cas9 system for the therapeutic correction of human genetic diseases. The most widely used homologs of the Cas9 protein are derived from the bacteria Staphylococcus aureus (S. aureus) and Streptococcus pyogenes (S. pyogenes). Based on the fact that these two bacterial species cause infections in the human population at high frequencies, we looked for the presence of pre-existing adaptive immune responses to their respective Cas9 homologs, SaCas9 (S. aureus homolog of Cas9) and SpCas9 (S. pyogenes homolog of Cas9). To determine the presence of anti-Cas9 antibodies, we probed for the two homologs using human serum and were able to detect antibodies against both, with 79% of donors staining against SaCas9 and 65% of donors staining against SpCas9. Upon investigating the presence of antigen-specific T-cells against the two homologs in human peripheral blood, we found anti-SaCas9 T-cells in 46% of donors. Upon isolating, expanding, and conducting antigen re-stimulation experiments on several of these donors' anti-SaCas9 T-cells, we observed an SaCas9-specific response confirming that these T-cells were antigen-specific. We were unable to detect antigenspecific T-cells against SpCas9, although the sensitivity of the assay precludes us from concluding that such T-cells do not exist. Together, this data demonstrates that there are pre-existing humoral and cell-mediated adaptive immune responses to Cas9 in humans, a factor which must be taken into account as the CRISPR-Cas9 system moves forward into clinical trials.

Episiotomy is the most common labour ward procedure in obstetrics. Improper healing of the episiotomy wound can lead to prolonged and sometimes serious post-partum morbidity. Also, if infected, they may manifest as a surgical site infection and may lead to generalised sepsis. In this study, we aim to critically evaluate cases of episiotomy wound gapes and study antenatal, intrapartum, and infective causes for the same. This study aimed to study the prevalence and causes of episiotomy wound dehiscence and the maternal co-morbidities associated with them in a tertiary care centre. Methods: This observational, hospital-based prospective cross-sectional study conducted at the Department of Obstetrics and Gynaecology, Seth GS Medical College and KEM Hospital from 2017-2018. A total of 30 cases of episiotomy wound dehiscence were studied. The rate of episiotomy wound dehiscence was 2.14% for the year 2017-2018. More than half (60%) of the patients have a wound dehiscence were overweight or obese. Anaemia, obesity, diabetes mellitus, and hypothyroidism were the main antenatal high-risk factors identified. In the intrapartum factors, wound dehiscence was more common in patients in whom labour was induced and those undergoing instrumental delivery. 70% of the cases were diagnosed between postpartum day 7-14, and the main presenting complaint was pain at the episiotomy site. The main organisms noted in infected wounds were Escherichia Coli and Klebsiella Pneumoniae. In conclusion, episiotomy wound dehiscence is an important cause of post-partum morbidity and prolonged hospital stay. This study revisits the need to correct antenatal factors like obesity, anaemia, and hypothyroidism and highlights the need to refine intrapartum practices and post-natal follow up in patients at high risk for this condition.

Mechanical ventilators are beneficial in treating and managing various respiratory diseases, including interstitial pneumonia associated with Coronavirus infection (COVID-19). The unprecedented COVID-19 pandemic has led to the emergence of a worldwide need for more accessible and affordable mechanical ventilatory devices. This project, known as the Third Coast Ventilator, aims to create a low-cost, open-source solution to the ventilator shortage created by the COVID-19 pandemic; this device can additionally be implemented in developing countries with limited medical resources, where ventilators are often inaccessible. Using readily available components found within hospitals and local stores, our team designed a prototype that can be assembled and functional within an hour. Our testing demonstrated accurate tidal volume delivery while modulating commonly used ranges of inspiratory to expiratory ratios, air flow rates, and respiratory rates. These promising results are an important step toward our goal of creating a low-cost, open-source, globally accessible ventilator in areas where shortages exist.