Influenza A infections: predictors of disease severity

Influenza affects approximately 10% of the world's population annually. It is associated with high morbidity and mortality rates due to its propensity to progress to severe acute respiratory infection, leading to 10-40% of hospitalized patients needing intensive care. Characterizing the multifactorial predictors of poor prognosis is essential for developing strategies against this disease. This study aimed to identify predictors of disease severity in influenza A-infected (IFA-infected) patients and to propose a prognostic score. A retrospective cross-sectional study was conducted with 142 IFA-infected out- and inpatients treated at a tertiary hospital between 2010 and 2018. The viral subtypes, hemagglutinin mutations, viral load, IL-28B SNPs, and clinical risk factors were evaluated according to the patient's ICU admission. Multivariate analysis identified the following risk factors for disease severity: neuromuscular diseases (OR = 7.02; 95% CI = 1.18-41.75; p = 0.032), cardiovascular diseases (OR = 5.47; 95% CI = 1.96-15.27; p = 0.001), subtype (H1N1) pdm09 infection (OR = 2.29; 95% CI = 1.02-5.15; p = 0.046), and viral load (OR = 1.43; 95% CI = 1.09-1.88; p = 0.009). The prognosis score for ICU admission is based on these predictors of severity presented and ROC curve AUC = 0.812 (p < 0.0001). Our results identified viral and host predictors of disease severity in IFA-infected patients, yielding a prognostic score that had a high performance in predicting the IFA patients' ICU admission and better results than a viral load value alone. However, its implementation in health services needs to be validated in a broader population.

Standardization of a high-performance RT-qPCR for viral load absolute quantification of influenza A

Influenza is an acute viral infectious respiratory disease worldwide, presenting in different clinical forms, from influenza-like illness (ILI) to severe acute respiratory infection (SARI). Although real-time quantitative polymerase chain reaction (qPCR) is already an important tool for both diagnosis and treatment monitoring of several viral infections, the correlation between the clinical aspects and the viral load of influenza is still unclear. This lack of clarity is primarily due to the low accuracy and reproducibility of the methodologies developed to quantify the influenza virus. Thus, this study aimed to develop and standardize a universal absolute quantification for influenza A by reverse transcription-quantitative PCR (RT-qPCR), using a plasmid DNA. The assay showed efficiency (Eff%) 98.6, determination coefficient (R₂⁾ 0.998, linear range 10^¹ to 10^¹⁰, limit of detection (LOD) 6.77, limit of quantification (LOQ) 20.52 copies/reaction. No inter and intra assay variability was shown, and neither was the matrix effect observed. Serial measurements of clinical samples collected at a 72h interval showed no change in viral load. By contrast, immunocompetent patients have a significantly lower viral load than immunosuppressed ones. Absolute quantification in clinical samples showed some predictors associated with increased viral load: (H1N1)pdm09 (0.045); women (p = 0.049) and asthmatics (p = 0.035). The high efficiency, precision, and previous performance in clinical samples suggest the assay can be used as an accurate universal viral load quantification of influenza A. Its applicability in predicting severity and response to antivirals needs to be evaluated.

Human metapneumovirus infection in hematopoietic stem cell transplant recipients

Human metapneumovirus (hMPV) was described in 2001 and has been associated with both upper and lower respiratory tract infection (URTI and LRTI, respectively), especially in children, the elderly, and in immunocompromised patients. The objective of this study was to identify hMPV as the etiological agent of acute respiratory infection in hematopoietic stem cell transplant (HSCT) patients and to determine the clinical features of hMPV infection in these patients.

METHODS

The study was performed retrospectively in 769 respiratory samples obtained from immunocompromised patients submitted to HSCT over a period of 6 years. RNA was extracted by the guanidinium thiocyanate method, and reverse transcription polymerase chain reaction assay was performed to amplify a 928pb fragment of the hMPV N gene.

RESULTS

hMPV was present in 19 (2.5%) samples. The mean age of infected patients was 18.3+/-10.8 (range, 3-41). Sixty-six percent of hMPV infections occurred during autumn, winter, and spring months. Three episodes showed co-infection with more than 1 virus. Two patients (11.1%) were infected a few days into the conditioning period and 9 (50%) in the first 3 months after the transplant. The majority of patients (72.2%) presented URTI alone with flu-like symptoms (cough, fever, headache, wheezing), while 5 patients (27.8%) had LRTI (pneumonia). No patient died from complications associated with the hMPV infection.

CONCLUSIONS

hMPV has been reported as a respiratory pathogen in HSCT patients. We suggest that hMPV infection should be routinely investigated in this population, mainly in children, to prevent nosocomial transmission during transplant proceedings and to avoid the risk of progressing to complications due to LRTI.

Stem and leaf morphoanatomy of Maytenus ilicifolia

Maytenus ilicifolia is a woody medicinal plant, employed mainly for its antiulcerogenic properties. The stem and leaf morphoanatomy has been studied, aiming to supply knowledge for the pharmacognostic and taxonomic species identification. The vegetative material was fixed, freehand sectioned and stained according to usual microtechniques. The stem organization, in secondary growth, shows periderm beneath the remaining epidermis, conspicuous sclerenchymatic ring in the cortex and cambium forming phloem outside and xylem inside. The leaf is simple, alternate and lanceolate and has sparsely spiny teeth along the margin. Epidermal cells containing calcium oxalate crystals, thick cuticle that forms cuticular flanges, dorsiventral mesophyll and amphicrival bundle in the midrib and petiole are observed.