T cell susceptibility to HIV influences outcome of opportunistic infections.

During HIV infection, the timing of opportunistic infections is not always associated with severity of CD4 T cell depletion, and different opportunistic pathogens reactivate at different CD4 T cell thresholds. Here, we examine how differences in the phenotype and function of pathogen-specific CD4 T cells influence susceptibility to HIV infection. By focusing on three common opportunistic infections (Mycobacterium tuberculosis, human papillomavirus, and cytomegalovirus), we investigate how differential depletion of pathogen-specific CD4 T cells impacts the natural history of these pathogens in HIV infection. A broader understanding of this relationship can better inform treatment strategies against copathogens.

SARS-CoV-2 infection and persistence in the human body and brain at autopsy.

Coronavirus disease 2019 (COVID-19) is known to cause multi-organ dysfunction1-3 during acute infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with some patients experiencing prolonged symptoms, termed post-acute sequelae of SARS-CoV-2 (refs. 4,5). However, the burden of infection outside the respiratory tract and time to viral clearance are not well characterized, particularly in the brain3,6-14. Here we carried out complete autopsies on 44 patients who died with COVID-19, with extensive sampling of the central nervous system in 11 of these patients, to map and quantify the distribution, replication and cell-type specificity of SARS-CoV-2 across the human body, including the brain, from acute infection to more than seven months following symptom onset. We show that SARS-CoV-2 is widely distributed, predominantly among patients who died with severe COVID-19, and that virus replication is present in multiple respiratory and non-respiratory tissues, including the brain, early in infection. Further, we detected persistent SARS-CoV-2 RNA in multiple anatomic sites, including throughout the brain, as late as 230 days following symptom onset in one case. Despite extensive distribution of SARS-CoV-2 RNA throughout the body, we observed little evidence of inflammation or direct viral cytopathology outside the respiratory tract. Our data indicate that in some patients SARS-CoV-2 can cause systemic infection and persist in the body for months.

Genetically Modified Porcine-to-Human Cardiac Xenotransplantation.

A 57-year-old man with nonischemic cardiomyopathy who was dependent on venoarterial extracorporeal membrane oxygenation (ECMO) and was not a candidate for standard therapeutics, including a traditional allograft, received a heart from a genetically modified pig source animal that had 10 individual gene edits. Immunosuppression was based on CD40 blockade. The patient was weaned from ECMO, and the xenograft functioned normally without apparent rejection. Sudden diastolic thickening and failure of the xenograft occurred on day 49 after transplantation, and life support was withdrawn on day 60. On autopsy, the xenograft was found to be edematous, having nearly doubled in weight. Histologic examination revealed scattered myocyte necrosis, interstitial edema, and red-cell extravasation, without evidence of microvascular thrombosis - findings that were not consistent with typical rejection. Studies are under way to identify the mechanisms responsible for these changes. (Funded by the University of Maryland Medical Center and School of Medicine.).

Histopathology and SARS-CoV-2 Cellular Localization in Eye Tissues of COVID-19 Autopsies.

Ophthalmic manifestations and tissue tropism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been reported in association with coronavirus disease 2019 (COVID-19), but the pathology and cellular localization of SARS-CoV-2 are not well characterized. The objective of this study was to evaluate macroscopic and microscopic changes and investigate cellular localization of SARS-CoV-2 across ocular tissues at autopsy. Ocular tissues were obtained from 25 patients with COVID-19 at autopsy. SARS-CoV-2 nucleocapsid gene RNA was previously quantified by droplet digital PCR from one eye. Herein, contralateral eyes from 21 patients were fixed in formalin and subject to histopathologic examination. Sections of the droplet digital PCR-positive eyes from four other patients were evaluated by in situ hybridization to determine the cellular localization of SARS-CoV-2 spike gene RNA. Histopathologic abnormalities, including cytoid bodies, vascular changes, and retinal edema, with minimal or no inflammation in ocular tissues were observed in all 21 cases evaluated. In situ hybridization localized SARS-CoV-2 RNA to neuronal cells of the retinal inner and outer layers, ganglion cells, corneal epithelia, scleral fibroblasts, and oligodendrocytes of the optic nerve. In conclusion, a range of common histopathologic alterations were identified within ocular tissue, and SARS-CoV-2 RNA was localized to multiple cell types. Further studies will be required to determine whether the alterations observed were caused by SARS-CoV-2 infection, the host immune response, and/or preexisting comorbidities.

Long-term outcomes after COVID-19 infection in transplant recipients.

BACKGROUND: Long-term outcomes after COVID-19 infection unique to solid organ transplant recipients (SOTR) are not published. We describe outcomes including readmission, allograft rejection, allograft dysfunction, allograft failure, and death. METHODS: We conducted a retrospective cohort study of mostly unvaccinated SOTR with COVID-19 from March 2020 to November 2021. Disease severity was assigned by NIH criteria. Data included demographics, clinical features, treatment, and outcomes and are presented as mean ± standard deviation or median (range). RESULTS: One hundred and thirty-eight SOTR were diagnosed with COVID-19 at a median of 5 (IQR 3-8) years post-transplant with a mean age of 57 ± 12 years at diagnosis. Forty-one recovered at home; 97 were admitted. 12/32 (37.5%) SOTR with critical disease expired during initial admission. Among those who recovered, 48/126 (38.0%) had asymptomatic or mild infection, 31/126 (24.6%) had moderate, 27/126 (21.4%) severe, and 20/126 (15.9%) critical infection. 38/85 (44.7%) of SOTR who survived initial admission had 74 readmissions within 180 days (Figure 1). The 6-month mortality rate among those who survived infection was 4/126 (3.2%). The mean time from initial infection to death was 32 ± 66 days in inpatient deaths and 95 ± 39 days in those who were discharged or never admitted. Six-month graft dysfunction occurred in 18/125 (14.4%) and graft failure in 9/126 (7.2%); five failures were deaths with function. CONCLUSION: Readmissions after COVID-19 infection were frequent after the index admission. Rejection was relatively infrequent; graft dysfunction at 6 months post-infection was more common than rejection. Six-month mortality following COVID-19 recovery in SOTR was significant; close follow-up of patients is warranted.

Heart of the matter-infection and xenotransplantation.

In this clinicopathological conference, invited experts discussed a previously published case of a patient with nonischemic cardiomyopathy who underwent heart transplantation from a genetically modified pig source animal. His complex course included detection of porcine cytomegalovirus by plasma microbial cell-free DNA and eventual xenograft failure. The objectives of the session included discussion of selection of immunosuppressive regimens and prophylactic antimicrobials for human xenograft recipients, description of infectious disease risk assessment and mitigation in potential xenograft donors and understanding of screening and therapeutic strategies for potential xenograft-related infections.

Infection and clinical xenotransplantation: Guidance from the Infectious Disease Community of Practice of the American Society of Transplantation.

This guidance was developed to summarize current approaches to the potential transmission of swine-derived organisms to xenograft recipients, health care providers, or the public in clinical xenotransplantation. Limited specific data are available on the zoonotic potential of pig pathogens. It is anticipated that the risk of zoonotic infection in xenograft recipients will be determined by organisms present in source animals and relate to the nature and intensity of the immunosuppression used to maintain xenograft function. Based on experience in allotransplantation and with preclinical models, viral infections are of greatest concern, including porcine cytomegalovirus, porcine lymphotropic herpesvirus, and porcine endogenous retroviruses. Sensitive and specific microbiological assays are required for routine microbiological surveillance of source animals and xenograft recipients. Archiving of blood samples from recipients, contacts, and hospital staff may provide a basis for microbiological investigations if infectious syndromes develop. Carefully implemented infection control practices are required to prevent zoonotic pathogen exposures by clinical care providers. Informed consent practices for recipients and their close contacts must convey the lack of specific data for infectious risk assessment. Available data suggest that infectious risks of xenotransplantation are manageable and that clinical trials can advance with carefully developed protocols for pretransplant assessment, syndrome evaluation, and microbiological monitoring.

Successful lung transplantation using an allograft from a COVID-19-recovered donor: a potential role for subgenomic RNA to guide organ utilization.

Although the risk of SARS-CoV-2 transmission through lung transplantation from acutely infected donors is high, the risks of virus transmission and long-term lung allograft outcomes are not as well described when using pulmonary organs from COVID-19-recovered donors. We describe successful lung transplantation for a COVID-19-related lung injury using lungs from a COVID-19-recovered donor who was retrospectively found to have detectable genomic SARS-CoV-2 RNA in the lung tissue by multiple highly sensitive assays. However, SARS-CoV-2 subgenomic RNA (sgRNA), a marker of viral replication, was not detectable in the donor respiratory tissues. One year after lung transplantation, the recipient has a good functional status, walking 1 mile several times per week without the need for supplemental oxygen and without any evidence of donor-derived SARS-CoV-2 transmission. Our findings highlight the limitations of current clinical laboratory diagnostic assays in detecting the persistence of SARS-CoV-2 RNA in the lung tissue. The persistence of SARS-CoV-2 RNA in the donor tissue did not appear to represent active viral replication via sgRNA testing and, most importantly, did not negatively impact the allograft outcome in the first year after lung transplantation. sgRNA is easily performed and may be a useful assay for assessing viral infectivity in organs from donors with a recent infection.

Impact of high MELD scores on CMV viremia following liver transplantation.

INTRODUCTION: Advanced liver disease or cirrhosis is associated with an increased risk of infections; however, the impact of high pretransplant model for end-stage liver disease (MELD) score on cytomegalovirus (CMV) viremia after liver transplantation is unknown. METHODS: This single-center, retrospective, cohort study evaluated CMV high-risk (CMV immunoglobulin G D+/R-) liver transplant recipients who received valganciclovir prophylaxis for 3 months between 2009 and 2019. Patients were stratified by pretransplant MELD score of <35 (low MELD) and ≥35 (high MELD). The primary outcome was 12-month CMV viremia, and secondary outcomes included CMV resistance and tissue invasive disease, mortality, biopsy-proven acute rejection (BPAR), leukopenia, and thrombocytopenia. Multivariable Cox proportional-hazards modeling was used to assess the association of MELD score with the time to CMV viremia. RESULTS: There were 162 and 79 patients in the low and high MELD groups, respectively. Pretransplant MELD score ≥35 was associated with an increased risk of CMV viremia (hazard ratio [HR] 1.73; confidence interval 1.06-2.82, p = .03). CMV viremia occurred at 162 ± 61 days in the low MELD group and 139 ± 62 days in the high MELD group. Although BPAR occurred early at 30 days (13-59) in the low-MELD group and at 18 days (11-66) in the high-MELD group (p = .56), BPAR was not associated with an increased risk of CMV viremia (HR 1.55 [0.93-2.60], p = .1). DISCUSSION: MELD scores ≥35 were associated with an increased hazards of CMV viremia. In liver transplant recipients with MELD scores ≥35 who are CMV high-risk, additional CMV intervention may be warranted.

Clinical characteristics of COVID-19 in solid organ transplant recipients following COVID-19 vaccination: A multicenter case series.

BACKGROUND: Solid organ transplant recipients (SOTR) have diminished humoral immune responses to COVID-19 vaccination and higher rates of COVID-19 vaccine breakthrough infection than the general population. Little is known about COVID-19 disease severity in SOTR with COVID-19 vaccine breakthrough infections. METHODS: Between 4/7/21 and 6/21/21, we requested case reports via the Emerging Infections Network (EIN) listserv of SARS-CoV-2 infection following COVID-19 vaccination in SOTR. Online data collection included patient demographics, dates of COVID-19 vaccine administration, and clinical data related to COVID-19. We performed a descriptive analysis of patient factors and evaluated variables contributing to critical disease or need for hospitalization. RESULTS: Sixty-six cases of SARS-CoV-2 infection after vaccination in SOTR were collected. COVID-19 occurred after the second vaccine dose in 52 (78.8%) cases, of which 43 (82.7%) occurred ≥14 days post-vaccination. There were six deaths, three occurring in fully vaccinated individuals (7.0%, n = 3/43). There was no difference in the percentage of patients who recovered from COVID-19 (70.7% vs. 72.2%, p = .90) among fully and partially vaccinated individuals. We did not identify any differences in hospitalization (60.5% vs. 55.6%, p = .72) or critical disease (20.9% vs. 33.3%, p = .30) among those who were fully versus partially vaccinated. CONCLUSIONS: SOTR vaccinated against COVID-19 can still develop severe, and even critical, COVID-19 disease. Two doses of mRNA COVID-19 vaccine may be insufficient to protect against severe disease and mortality in SOTR. Future studies to define correlates of protection in SOTR are needed.

An unusual case of Nocardia cyriacigeorgica presenting with spinal abscesses in a renal transplant recipient and a review of the literature.

Nocardia species represent a well-recognized yet uncommon cause of opportunistic infections in humans. It most frequently presents as a pulmonary infection with or without central nervous system involvement. It is a very rare cause of spinal abscesses, with only 26 cases reported in the literature. Here we report a 49-year-old man with a history of renal transplantation who presented with low back pain and was diagnosed with epidural and paraspinal abscesses due to Nocardia cyriacigeorgica that was successfully treated with antimicrobial therapy alone. In addition to the case reported here, we also conducted a systematic review of the existing literature regarding spinal abscesses due to Nocardia species and examined the success of the various treatments utilized.

Clinical outcomes of valganciclovir prophylaxis in high-risk (D+/R-) renal transplant recipients experiencing delayed graft function.

BACKGROUND: Cytomegalovirus (CMV) outcomes with valganciclovir prophylaxis in renal transplant recipients experiencing delayed graft function (DGF) are unclear. METHODS: This single center, retrospective, cohort study of CMV high-risk (D+/R- with alemtuzumab induction) deceased donor renal transplant recipients receiving valganciclovir prophylaxis assessed CMV outcomes in patients experiencing DGF (n = 72) versus those with immediate graft function (IGF; n = 66). RESULTS: Cytomegalovirus viremia by 12 months occurred at similar rates in the IGF and DGF groups (30.3% vs 26.4%, respectively, P = 0.71) with 89.7% (35/39) of all cases classified as CMV disease. The median time to CMV viremia post transplant was day 141 and 138 in the IGF and DGF groups, respectively (P = 0.30). The incidence of biopsy-proven acute rejection (BPAR) was higher in the DGF group (18.1% vs 4.6%, P = 0.02) with BPAR preceding CMV in only 1 patient. There was no significant difference in graft loss (1.5% vs 4.2%, P = 0.62) or patient survival (98.5% vs 95.8%, P = 0.62) at 1 year between the IGF and DGF groups, respectively. CONCLUSION: Valganciclovir prophylaxis in patients experiencing DGF yielded similar CMV outcomes up to 1-year post transplant when compared to use in patients with IGF.

Maternal transfer of IgA and IgG SARS-CoV-2 specific antibodies transplacentally and via breast milk feeding.

BACKGROUND: Although there have been many studies on antibody responses to SARS-CoV-2 in breast milk, very few have looked at the fate of these in the infant, and whether they are delivered to immunologically relevant sites in infants. METHODS: Mother/infant pairs (mothers who breast milk fed and who were SARS-CoV-2 vaccinated before or after delivery) were recruited for this cross-sectional study. Mother blood, mother breast milk, infant blood, infant nasal specimen, and infant stool was tested for IgA and IgG antibodies against SARS-CoV-2 spike trimer. RESULTS: Thirty-one mother/infant pairs were recruited. Breast milk fed infants acquired systemic anti-spike IgG antibodies only if their mothers were vaccinated antepartum (100% Antepartum; 0% Postpartum; P<0.0001). Breast milk fed infants acquired mucosal anti-spike IgG antibodies (in the nose) only if their mothers were vaccinated antepartum (89% Antepartum; 0% Postpartum; P<0.0001). None of the infants in either group had anti-spike IgA in the blood. Surprisingly, 33% of the infants whose mothers were vaccinated antepartum had high titer anti-spike IgA in the nose (33% Antepartum; 0% Postpartum; P = 0.03). Half-life of maternally transferred plasma IgG antibodies in the Antepartum infant cohort was ~70 days. CONCLUSION: Vaccination antepartum followed by breast milk feeding appears to be the best way to provide systemic and local anti-SARS-CoV-2 antibodies for infants. The presence of high titer SARS-CoV-2-specific IgA in the nose of infants points to the potential importance of breast milk feeding early in life for maternal transfer of mucosal IgA antibodies. Expectant mothers should consider becoming vaccinated antepartum and consider breast milk feeding for optimal transfer of systemic and mucosal antibodies to their infants.

Pulmonary Co-Infections Detected Premortem Underestimate Postmortem Findings in a COVID-19 Autopsy Case Series.

Bacterial and fungal co-infections are reported complications of coronavirus disease 2019 (COVID-19) in critically ill patients but may go unrecognized premortem due to diagnostic limitations. We compared the premortem with the postmortem detection of pulmonary co-infections in 55 fatal COVID-19 cases from March 2020 to March 2021. The concordance in the premortem versus the postmortem diagnoses and the pathogen identification were evaluated. Premortem pulmonary co-infections were extracted from medical charts while applying standard diagnostic definitions. Postmortem co-infection was defined by compatible lung histopathology with or without the detection of an organism in tissue by bacterial or fungal staining, or polymerase chain reaction (PCR) with broad-range bacterial and fungal primers. Pulmonary co-infection was detected premortem in significantly fewer cases (15/55, 27%) than were detected postmortem (36/55, 65%; p < 0.0001). Among cases in which co-infection was detected postmortem by histopathology, an organism was identified in 27/36 (75%) of cases. Pseudomonas, Enterobacterales, and Staphylococcus aureus were the most frequently identified bacteria both premortem and postmortem. Invasive pulmonary fungal infection was detected in five cases postmortem, but in no cases premortem. According to the univariate analyses, the patients with undiagnosed pulmonary co-infection had significantly shorter hospital (p = 0.0012) and intensive care unit (p = 0.0006) stays and significantly fewer extra-pulmonary infections (p = 0.0021). Bacterial and fungal pulmonary co-infection are under-recognized complications in critically ill patients with COVID-19.

Humoral immunity against SARS-CoV-2 variants including omicron in solid organ transplant recipients after three doses of a COVID-19 mRNA vaccine.

Objectives: Solid organ transplant recipients (SOTR) receiving post-transplant immunosuppression show increased COVID-19-related mortality. It is unclear whether an additional dose of COVID-19 vaccines can overcome the reduced immune responsiveness against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. Methods: We analysed humoral immune responses against SARS-CoV-2 and its variants in 53 SOTR receiving SARS-CoV-2 vaccination. Results: Following the initial vaccination series, 60.3% of SOTR showed no measurable neutralisation and only 18.9% demonstrated neutralising activity of > 90%. More intensive immunosuppression, antimetabolites in particular, negatively impacted antiviral immunity. While absolute IgG levels were lower in SOTR than controls, antibody titres against microbial recall antigens were higher. By contrast, SOTR showed reduced vaccine-induced IgG/IgA antibody titres against SARS-CoV-2 and its delta variants and fewer linear B-cell epitopes, indicating reduced B-cell diversity. Importantly, a third vaccine dose led to an increase in anti-SARS-CoV-2 antibody titres and neutralising activity across alpha, beta and delta variants and to the induction of anti-SARS-CoV-2 CD4+ T cells in a subgroup of patients analysed. By contrast, we observed significantly lower antibody titres after the third dose with the omicron variant compared to the ancestral SARS-CoV-2 and the improvement in neutralising activity was much less pronounced than for all the other variants. Conclusion: Only a small subgroup of solid organ transplant recipients is able to generate functional antibodies after an initial vaccine series; however, an additional vaccine dose resulted in dramatically improved antibody responses against all SARS-CoV-2 variants except omicron where antibody responses and neutralising activity remained suboptimal.

Utility of CMV-Specific Immune Monitoring for the Management of CMV in Solid Organ Transplant Recipients: A Clinical Update.

Cytomegalovirus (CMV) is one of the most important opportunistic infections in solid organ transplant (SOT) recipients. However, current techniques used to predict risk for CMV infection fall short. CMV-specific cell mediated immunity (CMI) plays an important role in protecting against CMV infection. There is evidence that assays measuring CMV-CMI might better identify SOT recipients at risk of complications from CMV compared to anti-CMV IgG, which is our current standard of care. Here, we review recently published studies that utilize CMV-CMI, at various points before and after transplantation, to help predict risk and guide the management of CMV infection following organ transplantation. The evidence supports the use of these novel assays to help identify SOT recipients at increased risk and highlights the need for larger prospective trials evaluating these modalities in this high-risk population.

Cryptococcosis.

Cryptococcosis is an invasive fungal infection of global significance caused by yeasts of the genus Cryptococcus. The prevalence of HIV in certain areas of the world and the expanding population of immunocompromised patients contribute to the ongoing global disease burden. Point-of-care serologic testing has allowed for more rapid diagnosis and implementation of screening programs in resource-limited settings. Management involves therapy aimed at reduction in fungal burden, maintenance of intracranial pressure, and optimization of host immunity. Despite diagnostic and therapeutic advances, cryptococcosis continues to be a disease with unacceptably high incidence and mortality, particularly in resource-limited settings.

Evidence of SARS-CoV-2-Specific T-Cell-Mediated Myocarditis in a MIS-A Case.

A 26-year-old otherwise healthy man died of fulminant myocarditis. Nasopharyngeal specimens collected premortem tested negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Histopathological evaluation of the heart showed myocardial necrosis surrounded by cytotoxic T-cells and tissue-repair macrophages. Myocardial T-cell receptor (TCR) sequencing revealed hyper-dominant clones with highly similar sequences to TCRs that are specific for SARS-CoV-2 epitopes. SARS-CoV-2 RNA was detected in the gut, supporting a diagnosis of multisystem inflammatory syndrome in adults (MIS-A). Molecular targets of MIS-associated inflammation are not known. Our data indicate that SARS-CoV-2 antigens selected high-frequency T-cell clones that mediated fatal myocarditis.