The three point asymmetric cumulants in high multiplicity pp collisions

We study the influence of quantum interference and colour flow on three point correlations described by asymmetric cumulants in high multiplicity events in pp collisions. We use the model previously developed for the study of the collectivity in symmetric cumulants. We show that the resulting three point asymmetric cumulant is in qualitative agreement with the experimental data for the same parameters of the model as it was with the symmetric cumulants. Our results show that the initial state correlations must play a major role and may be even dominant in the explanation of the correlations in high multiplicity pp events.

The colour matrix at next-to-leading-colour accuracy for tree-level multi-parton processes

We investigate the next-to-leading-colour (NLC) contributions to the colour matrix in the fundamental and the colour-flow decompositions for tree-level processes with all gluons, one quark pair and two quark pairs. By analytical examination of the colour factors, we find the non-zero elements in the colour matrix at NLC. At this colour order, together with the symmetry of the phase-space, it is reduced from factorial to polynomial the scaling of the contributing dual amplitudes as the number of partons participating in the scattering process is increased. This opens a path to an accurate tree-level matrix element generator of which all factorial complexity is removed, without resulting to Monte Carlo sampling over colour.

Towards colour flow evolution at two loops

We calculate the two-loop and one-loop/one-emission contributions required for soft gluon evolution at the next-to-leading order. The colour structures are expressed in the colour flow basis, and the kinematic dependence and loop integrals are expressed in terms of multiple cuts and phase-space-like integrals. This directly allows to use them in the resummation of non-global observables and improved parton shower algorithms beyond the leading order and beyond the leading colour limit. Within the colour flow basis it becomes apparent that correlations beyond a dipole picture emerge even in colour-diagonal elements of the virtual corrections.

825 Deep immune profiling of SARS-CoV-2 associated immune microenvironment in cancer tissues from recovered COVID-19 patients

BackgroundPersistence of SARS-CoV-2 virus particles in recovered COVID-19 patients remains a challenge as we continue to fight the ongoing pandemic. For instance, despite three negative consecutive nasopharyngeal swab PCR tests, residual SARS-CoV-2 was reported in the lungs of a deceased patient.1 Moreover, viral RNA could also be detected in rectal tissues that were obtained during incubation period.2 To date, there is no data regarding residual viral particles present in tissues from recovered COVID-19 patients. Hereby, we reported our findings of SARS-CoV-2 viral antigen in liver tissues from a recovered COVID-19 patient. These findings raise concern for potential transmissibility in recovered individuals.MethodsA 49-year-old South Asian male diagnosed with COVID-19 in June 2020, with incidental discovery of hepatitis B virus (HBV)-associated R0 Grade 2 hepatocellular carcinoma (HCC), was consented for our study. He did not develop significant acute respiratory symptoms throughout the course of the disease. He underwent curative resection of HCC 85 days after being tested COVID-19 negative where his blood, normal tissue and tumour samples were obtained for further analysis (figure 1). We performed deep immunopathological profiling on the specimens using multiplex immunohistochemistry and 25-colour flow cytometry to study SARS-CoV-2-elicited immune response.ResultsMultiplex immunohistochemistry detected SARS-CoV-2 nucleocapsid protein only in adjacent normal liver tissue but not within tumour core (figure 2). We also observed SARS-CoV-2 in some immune cells such as sinusoidal Kupffer cells (figure 2). Additionally, upon stimulation with SARS-CoV-2 peptides, we successfully elicited SARS-CoV-2-specific memory response which is distinct from the response upon challenge with HBV peptides. These findings were similar to our previous discovery in a patient with colorectal adenocarcinoma where we have shown viral antigen detection, validated with PCR to detect viral RNA, as well as the detection of SARS-CoV-2 memory-like T cells in situ (figure 2). Deep profiling of the samples is on-going with single-cell analysis and digital spatial profiling.Abstract 825 Figure 1Study design, methodology and brief summary of the findingsBlood, normal tissue and tumour samples were obtained from a 49-year-old South Asian male who was diagnosed with COVID-19 and hepatocellular carcinoma. Normal tissue and tumour samples were analysed with multiplex immunohistochemistry, while dissociated cells from blood and tissue samples were subjected to SARS-CoV-2 peptide stimulation and analysed with 25-colour flow cytometry. Multiplex immunohistochemistry detected SARS-CoV-2 proteins in both tumour and adjacent normal tissues, while flow cytometry identified distinct immune microenvironment involving memory-like T cells.Abstract 825 Figure 2Immunohistochemical staining of the SARS-CoV-2 nucleocapsid protein and immune profiling with 25-colour flow cytometry in normal colon and liver tissue a, Liver tissues were immunostained with SARS-CoV-2 nucleocapsid protein (NP), nuclei were counterstained with haematoxylin. Positive SARS-CoV-2 nucleocapsid staining in benign hepatocytes and sinusoidal Kupffer cells. Scale bar represents 50μm. b, Multiplex immunohistochemistry of normal liver tissue. From left to right, top to bottom: SARS-CoV-2 nucleocapsid (green), SARS-CoV-2 nucleocapsid (green) with CD14 (red), SARS-CoV-2 nucleocapsid (green) with CD68 (pink) and composite. Co-localisation were observed as shown by the white arrows. Scale bar represents 100μm. c, Colon tissues were immunostained with SARS-CoV-2 nucleocapsid protein, nuclei were counterstained with haematoxylin. Positive SARS-CoV-2 nucleocapsid staining in colonic crypts, with granular supranuclear cytoplasmic pattern. Scale bar represents 50μm. d, Multiplex immunohistochemistry of colon tissue. From left to right, top to bottom: DAPI (blue), CD3 (magenta), CD38 (green), granzyme B (yellow), interferon-gamma (red) and composite. Co-localisation was observed as shown by the white arrows. Scale bar represents 100μm, Magnification x200. e, Flow cytometry immune profiling of blood from colorectal cancer patient with COVID-19 following stimulation with SARS-CoV-2 peptides. Highlighted populations showed CD3 cells expressing CD38, supporting the CD3+ CD38+ co-localization findings observed in (c).ConclusionsWe believe this is the first immune profiling report of the in situ tumour microenvironment in a cancer patient with COVID-19. Our findings demonstrated the presence of viral proteins in the liver despite negative swab test result and the ability to elicit ex vivo SARS-CoV-2-specific immune responses through peptide stimulation assays. We also detected same immune cell phenotypes in situ in the cancer tissues. Taken together, we propose caution when handling tissues from patients who have a recent history of COVID-19, particularly during aerosol-generating procedures such as ultrasonic dissection surgery.Ethics ApprovalThis study was approved by Centralised Institutional Review Board of SingHealth, approval number 2019/2653.ConsentWritten informed consent was obtained from the patient for publication of this abstract and any accompanying images. A copy of the written consent is available for review by the Editor of this journal.ReferencesYao XH, He ZC, Li TY, Zhang HR, Wang Y, Mou H, et al. Pathological evidence for residual SARS-CoV-2 in pulmonary tissues of a ready-for-discharge patient. Cell Res 2020;30(6):541-3.Qian Q, Fan L, Liu W, Li J, Yue J, Wang M, et al. Direct evidence of active SARS-CoV-2 replication in the intestine. Clin Infect Dis 2020.

168 Comparison of different Doppler ultrasound settings for pregnancy diagnosis based on corpus luteum perfusion at 21 days after AI in beef cattle

Colour Doppler ultrasonography of the corpus luteum (CL) can be used for early pregnancy diagnosis to improve reproductive efficiency and increase the use of AI in beef cattle. The objective of the present study was to determine the diagnostic performance of different Doppler ultrasonography settings for pregnancy diagnosis based on CL perfusion at 21 days after fixed-time AI in beef heifers and cows. Yearling Angus-cross heifers (n=25) and suckled Angus-cross cows (n=84) aged 2-13 years were submitted to a 5-day CO-Synch + controlled internal drug release (CIDR) and timed AI at 60 or 72h after CIDR removal for heifers and cows, respectively. Animals were evaluated by a single operator using colour Doppler ultrasonography (Esaote MyLab Delta) at Day 21. Three settings for colour flow mapping (720, 960, and 1500Hz) and one setting for power Doppler (960Hz), which differed in pulse repetition frequency, were evaluated. The other settings remained unchanged with a probe frequency of 6.3MHz, wall filter of 3, and gain of 61. The pregnancy status (pregnant or non-pregnant) of cows and heifers was determined at 21 days following insemination using colour Doppler ultrasonography. Cows and heifers were considered to be pregnant if the CL blood flow area covered >10% of the periphery of the CL and contained at least two colour internal tracts penetrating towards the centre of the CL. Cattle were evaluated using transrectal B-mode ultrasonography on Day 35 to determine actual pregnancy status. Differences between diagnostic performance variables were evaluated using logistic regression, and setting, category (heifer or cow), and the interaction were included as fixed effects. Pregnancies per AI at Day 35 after fixed-time AI were 47.7% (52/109). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for pregnancy diagnosis at Day 21 for each setting are included in Table 1. There were no differences in sensitivity and NPV between settings (P>0.9), category (P>0.9), or the interaction (P>0.9). There was no effect of setting (P>0.5) or category×setting interaction (P>0.8) on specificity and PPV. There was, however, an effect of category (P<0.01). Colour Doppler ultrasonography had less specificity (59.1% compared with 90.2%) and PPV (75% compared with 89.3%) in heifers than in cows. In conclusion, colour Doppler ultrasonography settings that were evaluated did not affect the diagnostic performance for pregnancy diagnosis at Day 21 after AI, although, numerically the colour flow mapping at 960Hz appears to maximise diagnostic accuracy. In addition, the false-positive rate was greater in heifers, which warrants further research. Table 1.Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for pregnancy diagnosis for four colour Doppler ultrasound settings (colour flow mapping (CFM) at 720, 960, and 1500Hz and power Doppler (PWD) at 960Hz) at 21 days after fixed-time AI Item CFM720 CFM960 CFM1500 PWD960 Sensitivity,% 100 100 92.3 100 Specificity,% 80.7 87.7 87.7 80.7 PPV,% 82.5 88.1 87.3 82.5 NPV,% 100 100 92.6 100