Role of picornaviruses in flu-like illnesses of adults enrolled in an oseltamivir treatment study who had no evidence of influenza virus infection

Abstract

The primary objective of this study was to determine the role of picornavirus in flu-like episodes (temperature of > or =38.0 degrees C plus one respiratory and one constitutional symptom) among otherwise healthy adults enrolled in a placebo-controlled, double-blind, randomized oseltamivir treatment study. Combined nasal and pharyngeal swabs were collected at baseline for influenza cultures and picornavirus reverse transcription (RT)-PCR. In addition, acute- and convalescent-serum samples were obtained for serological studies of common respiratory pathogens. From a total of 719 subjects enrolled in the clinical trial within 36 h of the onset of symptoms, 475 (66%) had evidence of recent influenza A or B virus infections by means of culture and/or serological testing. Of the 244 remaining patients, 36 (15%) presented a seroconversion for at least one of the common respiratory viruses or atypical pathogens. An RT-PCR assay for the picornavirus 5" noncoding region (NCR) was positive in a subset of 15 (19%) of 78 patients with flu-like illnesses of undetermined etiology. Sequence analysis of the picornavirus 5" NCR amplicons revealed that 14 (93%) of them had greater homology to rhinoviruses, whereas 1 (7%) was related to enteroviruses. Interestingly, median total symptom scores and oral temperatures of picornavirus-positive patients (n = 15) and placebo-treated influenza virus-positive patients (n = 161) were similar over a 3-week period. We conclude that, among the influenza virus-negative preselected cases of this study, rhinoviruses were relatively frequent pathogens associated with important respiratory and systemic symptoms.

FIG. 1.

Overview of laboratory results in a treatment study of influenza-like illness with oseltamivir. ∗, adenovirus (n = 5), PIV (n = 5), RSV (n = 5), M. pneumoniae (n = 4), C. pneumoniae (n = 10), mixed infections (n = 7).

FIG. 2.

Detection of picornaviruses in nasopharyngeal swab eluates by RT-PCR followed by chemiluminescent hybridization. The upper panel represents the ethidium bromide-stained gel of amplified picornavirus products, whereas the lower panel represents the corresponding hybridization with the rhinovirus probe. Lanes: 1, 100-bp ladder; 2, blank; 3, negative nasopharyngeal sample; 4, positive nasopharyngeal sample; 5 to 13, 50, 100, 250, 500, 1,000, 2,500, 5,000, 10,000, and 25,000 copies of a rhinovirus plasmid, respectively; 14, enterovirus control isolate; 15, rhinovirus control isolate.

FIG. 3.

Median oral temperatures (A) and median total symptom scores (B) over time for 15 picornavirus-positive and 161 placebo-treated influenza virus-positive patients with influenza-like illnesses. Total symptom scores were calculated according to the presence and severity of seven symptoms (cough, sore throat, nasal congestion, headache, myalgia, sweat or chills, and fatigue) on a four-point scale (0, absent; 1, mild; 2, moderate; 3, severe). All patients received no antivirals but were allowed to use symptomatic relief medication (acetaminophen).