Increased virus dissemination leads to enhanced lung injury but not inflammation during influenza-associated secondary bacterial infection

Quantitatively Mapping Immune Control during Influenza

Host immune responses play a pivotal role in defending against influenza viruses. The activation of various immune components, such as interferon, macrophages, and CD8+ T cells, works to limit viral spread while maintaining lung integrity. Recent mathematical modeling studies have investigated these responses, describing their regulation, efficacy, and movement within the lung. Here, we discuss these studies and their emphasis on identifying nonlinearities and multifaceted roles of different cell phenotypes that could be responsible for spatially heterogeneous infection patterns.

Toward mechanistic medical digital twins: some use cases in immunology

A fundamental challenge for personalized medicine is to capture enough of the complexity of an individual patient to determine an optimal way to keep them healthy or restore their health. This will require personalized computational models of sufficient resolution and with enough mechanistic information to provide actionable information to the clinician. Such personalized models are increasingly referred to as medical digital twins. Digital twin technology for health applications is still in its infancy, and extensive research and development is required. This article focuses on several projects in different stages of development that can lead to specific-and practical-medical digital twins or digital twin modeling platforms. It emerged from a two-day forum on problems related to medical digital twins, particularly those involving an immune system component. Open access video recordings of the forum discussions are available.

Staphylococcus epidermidis induced toxic shock syndrome (TSS) secondary to influenza infection

BACKGROUND

To date, few cases of TSS caused by coagulase negative (CoN) staphylococci have been reported in the literature. Recent data show that CoN staphylococci are capable of secreting a number of enterotoxins and cytotoxins, normally produced by S. aureus. Herewith, we describe a case of TSS caused by Staphylococcus epidermidis with a favorable outcome.

CASE PRESENTATION

We report a case of a 46-year-old man who developed TSS from S. epidermidis. The patient was admitted for a 7-day history of general malaise and headache following a recent influenza infection and a 3-day history of vomiting, diarrhea, diffuse erythroderma, and fever. The main laboratory findings on admission were leukopenia (WBC 800/mm3), thrombocytopenia (Plt count 78.000/mm3), elevated urea, creatine levels and increased inflammatory markers (CRP 368 mg/ml). The patient had clinical and radiological evidence of pneumonia with chest computed tomography (CT) showing diffuse bilateral airspace opacifications with air bronchogram. On the second day, a methicillin resistant S. epidermidis (MRSE) strain was detected in both sets of blood cultures, but the organism was unavailable for toxin testing. All other cultures and diagnostic PCR tests were negative. His clinical signs and symptoms fulfilled at that stage four out of five clinical criteria of TSS with a fever of 39 °C, diffuse erythroderma, multisystem involvement and hypotension. On the same day the patient was admitted to the ICU due to acute respiratory failure. The initial treatment was meropenem, vancomycin, levofloxacin, clindamycin, IVIG and steroids. Finger desquamation appeared on the 9th day of hospitalization, fulfilling all five clinical criteria for TSS.

CONCLUSIONS

To our knowledge, this is the first adult case with TSS induced by CoNS (MRSE) secondary to an influenza type B infection, who had favorable progression and outcome. Further research is warranted to determine how TSS is induced by the CoNS infections.

How Interactions during Viral-Viral Coinfection Can Shape Infection Kinetics

Respiratory viral infections are a leading global cause of disease with multiple viruses detected in 20-30% of cases, and several viruses simultaneously circulating. Some infections with unique viral copathogens result in reduced pathogenicity, while other viral pairings can worsen disease. The mechanisms driving these dichotomous outcomes are likely variable and have only begun to be examined in the laboratory and clinic. To better understand viral-viral coinfections and predict potential mechanisms that result in distinct disease outcomes, we first systematically fit mathematical models to viral load data from ferrets infected with respiratory syncytial virus (RSV), followed by influenza A virus (IAV) after 3 days. The results suggest that IAV reduced the rate of RSV production, while RSV reduced the rate of IAV infected cell clearance. We then explored the realm of possible dynamics for scenarios that had not been examined experimentally, including a different infection order, coinfection timing, interaction mechanisms, and viral pairings. IAV coinfection with rhinovirus (RV) or SARS-CoV-2 (CoV2) was examined by using human viral load data from single infections together with murine weight-loss data from IAV-RV, RV-IAV, and IAV-CoV2 coinfections to guide the interpretation of the model results. Similar to the results with RSV-IAV coinfection, this analysis shows that the increased disease severity observed during murine IAV-RV or IAV-CoV2 coinfection was likely due to the slower clearance of IAV-infected cells by the other viruses. The improved outcome when IAV followed RV, on the other hand, could be replicated when the rate of RV infected cell clearance was reduced by IAV. Simulating viral-viral coinfections in this way provides new insights about how viral-viral interactions can regulate disease severity during coinfection and yields testable hypotheses ripe for experimental evaluation.

How Interactions During Viral-Viral Coinfection Can Shape Infection Kinetics

Respiratory virus infections are a leading cause of disease worldwide with multiple viruses detected in 20-30% of cases and several viruses simultaneously circulating. Some infections with viral copathogens have been shown to result in reduced pathogenicity while other virus pairings can worsen disease. The mechanisms driving these dichotomous outcomes are likely variable and have only begun to be examined in the laboratory and clinic. To better understand viral-viral coinfections and predict potential mechanisms that result in distinct disease outcomes, we first systematically fit mathematical models to viral load data from ferrets infected with respiratory syncytial virus (RSV) followed by influenza A virus (IAV) after 3 days. The results suggested that IAV reduced the rate of RSV production while RSV reduced the rate of IAV infected cell clearance. We then explored the realm of possible dynamics for scenarios not examined experimentally, including different infection order, coinfection timing, interaction mechanisms, and viral pairings. IAV coinfection with rhinovirus (RV) or SARS-CoV-2 (CoV2) was examined by using human viral load data from single infections together with murine weight loss data from IAV-RV, RV-IAV, and IAV-CoV2 coinfections to guide the interpretation of the model results. Similar to the results with RSV-IAV coinfection, this analysis showed that the increased disease severity observed during murine IAV-RV or IAV-CoV2 coinfection was likely due to slower clearance of IAV infected cells by the other viruses. On the contrary, the improved outcome when IAV followed RV could be replicated when the rate of RV infected cell clearance was reduced by IAV. Simulating viral-viral coinfections in this way provides new insights about how viral-viral interactions can regulate disease severity during coinfection and yields testable hypotheses ripe for experimental evaluation.