Sudden death in a toddler with laryngotracheitis caused by human parainfluenza virus-1

The landscape of extrapulmonary manifestations of human parainfluenza viruses: A systematic narrative review

Human parainfluenza virus (HPIV) infection is associated with every kind of respiratory tract illnesses, including the common cold, laryngotracheobronchitis (i.e. croup), tracheobronchitis, bronchiolitis, and pneumonia, in both children and adults. Although HPIVs are common respiratory pathogens, there are increasing reports about extrapulmonary manifestations of HPIVs infection. Each of the HPIVs could produce infection of other organs (central nervous system, heart, myocardium, etc.) in all age groups who are either immunocompetent or immunocompromised. This review aimed at summarizing the available data on clinical manifestations of HPIV infection outside the respiratory tract from 1961 to 2020. The findings support the possibility of extrapulmonary infections that were thought to be due to rare host genetic or immunologic defects in infected patients. These findings highlight the fact that extrapulmonary dissemination of HPIV can occur, but the association is not clearly demonstrated. Our data support the hypothesis that HPIV infection is one of the possible causes of these alterations and may even be the direct cause in some cases.

A I131V Substitution in the Fusion Glycoprotein of Human Parainfluenza Virus Type 1 Enhances Syncytium Formation and Virus Growth

Human parainfluenza virus type 1 (hPIV1) has two spike glycoproteins, the hemagglutinin-neuraminidase (HN) glycoprotein as a receptor-binding protein and the fusion (F) glycoprotein as a membrane-fusion protein. The F glycoprotein mediates both membrane fusion between the virus and cell and membrane fusion between cells, called syncytium formation. Wild-type C35 strain (WT) of hPIV1 shows little syncytium formation of infected cells during virus growth. In the present study, we isolated a variant virus (Vr) from the WT that showed enhanced syncytium formation of infected cells by using our previously established hPIV1 plaque formation assay. Vr formed a larger focus and showed increased virus growth compared with WT. Sequence analysis of the spike glycoprotein genes showed that the Vr had a single amino acid substitution of Ile to Val at position 131 in the fusion peptide region of the F glycoprotein without any substitutions of the HN glycoprotein. The Vr F glycoprotein showed enhanced syncytium formation in F and HN glycoprotein-expressing cells. Additionally, expression of the Vr F glycoprotein increased the focus area of the WT-infected cells. The single amino acid substitution at position 131 in the F glycoprotein of hPIV1 gives hPIV1 abilities to enhance syncytium formation and increase cell-to-cell spread. The present study supports the possibility that hPIV1 acquires increased virus growth in vitro from promotion of direct cell-to-cell transmission by syncytium formation.

Obstructive apnea due to laryngospasm links ictal to postictal events in SUDEP cases and offers practical biomarkers for review of past cases and prevention of new ones

Seizure spread into autonomic and respiratory brainstem regions is thought to play an important role in sudden unexpected death in epilepsy (SUDEP). As the clinical dataset of cases of definite SUDEP available for study grows, evidence points to a sequence of events that includes postictal apnea, bradycardia, and asystole as critical events that can lead to death. One possible link between the precipitating seizure and the critical postictal sequence is seizure-driven laryngospasm sufficient to completely obstruct the airway for an extended period, but ictal laryngospasm is difficult to fully assess. Herein, we demonstrate in a rat model how the electrical artifacts of attempts to inspire during airway obstruction and features of the cardiac rhythm establish this link between ictal and postictal activity and can be used as practical biomarkers of obstructive apnea due to laryngospasm or other causes of airway obstruction.

Post-mortem diagnosis, of cytomegalovirus and varicella zoster virus co-infection by combined histology and tissue molecular biology, in a sudden unexplained infant death

BACKGROUND

An autopsy case of a two-month-old male infant who suddenly and unexpectedly died during his sleep, eight days after the onset of benign varicella.

OBJECTIVES

To describe post-mortem combined histological and tissue molecular biological techniques for the diagnosis of cytomegalovirus and varicella zoster virus co-infection as a cause of death.

STUDY DESIGN

Real-time quantitative PCR and RT-PCR assays for Herpesviruses, respiratory viruses, Adenovirus, Enterovirus and Parvovirus B19 were performed on multi-organ frozen samples and paraffin-embedded tissues in combination with histology.

RESULTS

Cytomegalovirus and varicella zoster virus were detected by molecular biology with highest viral loads detected in the lungs (4.6×10(7) and 1.9×10(5) genome copies per million of cells, respectively). Pulmonary extensive necrotizing inflammation and immunohistochemistry correlated to virological data. Virological molecular biology was negative on paraffin-embedded tissues.

CONCLUSIONS

This case shows that thorough quantitative virological investigations on frozen tissues must be performed in combination with histology and immunohistochemistry for the determination of the cause of a sudden unexplained infant death.

Otolaryngological aspects of sudden infant death syndrome

INTRODUCTION

Sudden infant death syndrome (SIDS) is characterized by the sudden death of an apparently otherwise healthy infant, typically during sleep, and with no obvious case after a thorough post-mortem and scene death examination.

OBJECTIVE

To address the problem from the otolaryngologist's perspective, describe relevant pathologies, discuss controversies and suggest preventive measures in high-risk populations.

METHODOLOGY

A MEDLINE search and hand search were conducted to identify reports published between 1969 and 2011 in the English language on the pathophysiology of SIDS related to the head and neck organs. Search terms included SIDS (MeSH term), SIDS and pathophysiology (text words), and SIDS and autopsy (text words).

DISCUSSION

A growing number of reports suggested head and neck organs involvement in SIDS autopsies. Laryngeal, oropharyngeal, maxillofacial, otologic, cervical vascular abnormalities and infectious etiologies, were recognized and discussed.

CONCLUSIONS

Otolaryngologists should be aware of relevant pathologies, as some are treatable, if identified early enough in infancy. A proactive risk-management approach is warranted in infants presenting with certain abnormalities reviewed here.

Plaque formation assay for human parainfluenza virus type 1

Human parainfluenza virus type 1 (hPIV1) generally does not show visible plaques in common cell lines, including Lewis lung carcinoma-monkey kidney (LLC-MK(2)) cells, by plaque formation assays for human parainfluenza virus type 3 (hPIV3) and Sendai virus. In several conditions of the plaque formation assay, complete elimination of serum proteins in the overlay medium was necessary for visualization of hPIV1-induced plaque formation in LLC-MK(2) cells. We developed a plaque formation assay for hPIV1 isolation and titration in LLC-MK(2) cells using an initial overlay medium of bovine serum albumin-free Eagle's minimum essential medium containing agarose and acetylated trypsin for 4-6 d followed by a second overlay staining medium containing agarose and neutral red. The assay allowed both laboratory and clinical hPIV1 strains to form large plaques. The plaque reduction assay was also performed with rabbit anti-hPIV1 antibody as a general evaluation model of viral inhibitors to decrease both the plaque number and size. The results indicate that the plaque formation assay is useful for hPIV1 isolation, titration, evaluation of antiviral reagents and epidemiologic research.