Microarray detection of human parainfluenzavirus 4 infection associated with respiratory failure in an immunocompetent adult

Abstract

A pan-viral DNA microarray, the Virochip (University of California, San Francisco), was used to detect human parainfluenzavirus 4 (HPIV-4) infection in an immunocompetent adult presenting with a life-threatening acute respiratory illness. The virus was identified in an endotracheal aspirate specimen, and the microarray results were confirmed by specific polymerase chain reaction and serological analysis for HPIV-4. Conventional clinical laboratory testing using an extensive panel of microbiological tests failed to yield a diagnosis. This case suggests that the potential severity of disease caused by HPIV-4 in adults may be greater than previously appreciated and illustrates the clinical utility of a microarray for broad-based viral pathogen screening.

Figure 1

Imaging and lung pathology from the patient. A chest radiograph (A) obtained at admission revealed bilateral reticulonodular infiltrates with associated lower lobe consolidations, whereas a CT scan (representative slice; B) showed bilateral centrilobular nodules with a tree-in-bud appearance suggestive of bronchiolitis. After intubation, a chest radiograph was performed on the patient on hospital day 4 that revealed persistent bilateral infiltrates (C). On day 7 after hospital admission, findings from lung biopsy analysis revealed an organizing bronchiolitis but no direct histological evidence of virus infection (hematoxylin and eosin stain, low magnification; D).

Figure 2

Graphic representation of the human parainfluenzavirus 4 (HPIV-4) genome (A). The major viral proteins include the nucleocapsid protein (NP), phosphoprotein (P), nonstructural V protein (V), matrix protein (M), fusion protein (F), hemagglutinin-neuraminidase protein (HN), and large protein (L). The locations of the 6 paramyxovirus oligonucleotides used to detect HPIV-4 on the microarray are mapped onto the ∼15 kB genome (B). The corresponding z-score for each oligonucleotide is indicated in parentheses. Five regions of the HPIV-4 virus obtained from a sample of the patient's endotracheal aspirate were sequenced (a–e, black areas), 4 of which are within previously sequenced regions of the genome (gray areas; C). Below each sequenced region is its percentage of nucleotide identity to the corresponding HPIV-4a sequence in the GenBank database.

Figure 3

Detection of antibody to human parainfluenzavirus 4 (HPIV-4) by indirect immunofluorescence. A, Plot of the patient's serum HPIV-4 IgG antibody titers over time. The 5 successive time points correspond to days 13, 23, 24, 31, and 51 after symptom onset, the pink background outlines the period of hospitalization, and the asterisk designates the time point corresponding to panel B. The cytoplasm of infected cells (white arrows) stains green against a background of uninfected cells in red (B).