Mechanisms of Human Adenovirus Inactivation by Sunlight and UVC Light as Examined by Quantitative PCR and Quantitative Proteomics

Abstract

Human adenoviruses (HAdV) are important pathogens in both industrialized and developing nations. HAdV has been shown to be relatively resistant to monochromatic UVC light. Polychromatic UVC light, in contrast, is a more effective means of disinfection, presumably due to the involvement of viral proteins in the inactivation mechanism. Solar disinfection of HAdV, finally, is only poorly understood. In this paper, the kinetics and mechanism of HAdV inactivation by UVC light and direct and indirect solar disinfection are elucidated. PCR and mass spectrometry were employed to quantify the extent of genome and protein degradation and to localize the affected regions in the HAdV proteins. For this purpose, we used for the first time an approach involving stable isotope labeling by amino acids in cell culture (SILAC) of a human virus. Inactivation by UVC light and the full sunlight spectrum were found to efficiently inactivate HAdV, whereas UVA-visible light only caused inactivation in the presence of external sensitizers (indirect solar disinfection). Genome damage was significant for UVC but was less important for solar disinfection. In contrast, indirect solar disinfection exhibited extensive protein degradation. In particular, the fiber protein and the amino acids responsible for host binding within the fiber protein were shown to degrade. In addition, the central domain of the penton protein was damaged, which may inhibit interactions with the fiber protein and lead to a disruption of the initial stages of infection. Damage to the hexon protein, however, appeared to affect only regions not directly involved in the infectious cycle.

Solar Disinfection of Viruses in Polyethylene Terephthalate Bottles

“…It thus appears that the light-independent inactivation of HAdV masks the effects of direct or indirect photoinactivation in our experimental system. In contrast, in previous work by our group using a different batch of Swiss tap water than the one tested herein, we observed a very low rate of dark inactivation and consequently a measurable effect of simulated sunlight on HAdV inactivation in a PET bottle (25). Similarly, Carratalà et al observed a 2-log decay of HAdV in mineral water exposed to UVA and visible light for 24 h, while inactivation in the dark was negligible (23).…”

“…HAdVs are large double-stranded DNA pathogens ( Table 1) that cause a wide variety of infections and are widely prevalent in the environment (19)(20)(21). They have been suggested to be indicators of human fecal contamination and have been included in many disinfection studies as a process control (22)(23)(24)(25)(26)(27). From our data, ϳ3-log inactivation would occur at a fluence of 1.34 kJ/cm 2 ( HAdV ϭ 4.58 Ϯ 0.26 cm 2 /kJ) (Fig.…”

Solar and Temperature Treatments Affect the Ability of Human Rotavirus Wa To Bind to Host Cells and Synthesize Viral RNA

“…Of these transient species, hydroxyl radicals and triplet state species have been implicated with the inactivation of human rotavirus at 25°C; this mechanism of inactivation is referred to as exogenous (16). Based on work with MS2 bacteriophage and adenovirus type 2, a reasonable hypothesis is that solar treatment damages the rotavirus genome and capsid proteins, preventing virus attachment and viral genome replication (21,22). In contrast, heat treatment is expected to destabilize the rotavirus capsid, as shown with heated MS2 bacteriophage, adenovirus type 5 proteins, parvoviruses, human picornavirus, and feline calicivirus, preventing the initial virus-host cell interactions that are required for a productive virus infection (21,(23)(24)(25).…”

Tracking Human Adenovirus Inactivation by Gamma Radiation under Different Environmental Conditions

“…Generally, damage to the viral capsid can result in the loss of its capacity to protect the viral genome and its ability to replicate in the host (44). Alteration in the adenovirus hexon protein may alter the shape of the nucleocapsid and interfere negatively with the virus' life cycle (2). The potential alterations of the capsid proteins detected by ELISA seem like they do not correlate with the loss of infectivity with the increase of gamma radiation dose estimated by plaque assay.…”

“…As one of the few enteric viruses with a doublestranded DNA (dsDNA) genome, human adenovirus (HAdV) is known for its high stability and persistence in aquatic environments compared to other viruses (2,3). The adenovirus is recognized as the most prevalent enteric virus in waters worldwide, which can cause serious implications for public health (4).…”