Airborne rhinovirus detection and effect of ultraviolet irradiation on detection by a semi-nested RT-PCR assay

BACKGROUND: Rhinovirus, the most common cause of upper respiratory tract infections, has been implicated in asthma exacerbations and possibly asthma deaths. Although the method of transmission of rhinoviruses is disputed, several studies have demonstrated that aerosol transmission is a likely method of transmission among adults. As a first step in studies of possible airborne rhinovirus transmission, we developed methods to detect aerosolized rhinovirus by extending existing technology for detecting infectious agents in nasal specimens. METHODS: We aerosolized rhinovirus in a small aerosol chamber. Experiments were conducted with decreasing concentrations of rhinovirus. To determine the effect of UV irradiation on detection of rhinoviral aerosols, we also conducted experiments in which we exposed aerosols to a UV dose of 684 mJ/m(2). Aerosols were collected on Teflon filters and rhinovirus recovered in Qiagen AVL buffer using the Qiagen QIAamp Viral RNA Kit (Qiagen Corp., Valencia, California) followed by semi-nested RT-PCR and detection by gel electrophoresis. RESULTS: We obtained positive results from filter samples that had collected at least 1.3 TCID(50 )of aerosolized rhinovirus. Ultraviolet irradiation of airborne virus at doses much greater than those used in upper-room UV germicidal irradiation applications did not inhibit subsequent detection with the RT-PCR assay. CONCLUSION: The air sampling and extraction methodology developed in this study should be applicable to the detection of rhinovirus and other airborne viruses in the indoor air of offices and schools. This method, however, cannot distinguish UV inactivated virus from infectious viral particles

Short-Duration Exposure and the Transmission of Rhinoviral Colds

Transmission of infection with rhinovirus type 55 was attempted under natural circum-stances of interaction among 26 experimentally infected donors and 33 antibody-free (titer, <1:3) recipients. In a total of three experiments, only two recipients (6070) became infected. In the first experiment no transmissions from five donors to nine recipients occurred after 2-3 hr of loud vocalization and card playing in a small room. In the second experiment a cold was transmitted to one (9070) of 11 recipients living in dormi-tory rooms for 36 hr in groups consisting chiefly of two donors and two recipients. In the third experiment one (8%) of 13 recipients was infected after kissing an infected donor. In studies with rhinovirus type 16, the 50 % human infectious dose was found to be 0.28 TCID so (50 % tissue culture infectious dose) in the nose, 2,260 TCID so on the tongue, and 11,000 TCID so on the external nares. Rhinoviral infections are difficult to transmit by short-term natural exposure, perhaps because the agent must be present in overwhelming numbers to reach susceptible mucosal cells. The rhinoviruses are the agents most often associ-ated with the common cold syndrome and ar