UV Disinfection of Norwalk Virus and Other Enteric Viruses and Their Detection by RT-PCR

Norwalk virus (NV) is an important cause of waterborne gastroenteritis, yet its response to UV disinfection is unknown. Non-culturable and without an animal model, reverse-transcription PCR (RT-PCR) or an alternative nucleic acid amplification method is the only practical way to detect and quantify this virus in water. However, we have found that RT-PCR under estimates the loss of virus infectivity by UV radiation. In an effort to improve the predictability of RT-PCR amplification for the loss of virus infectivity by UV disinfection, we investigated alternatives to single amplicon, direct RT-PCR. In addition to NV, coliphage MS2 as well as polio virus type 3 (PV3) and type 1 (PV1) were included in the study to compare infectivity assays to RT-PCR assays for quantifying virus inactivation by UV radiation. Based on infectivity assays, a UV dose of 150 mW-sec/cm^2 reduced MS2 and PV1 by 4.8 and ≥ 5.8log[10], respectively. By direct RT-PCR amplification of genomic targets of about 200-250 BP, this dose of UV radiation produced from zero to 1 log[10] titer reduction in any of the three viruses. In order to improve the detection of UV damage to viral genomic RNA, RT-PCR amplification was performed at multiple targets. However, even at a high dose of 550 mW-sec/cm^2, there was no increase in the observed reduction in virus titer by RT-PCR amplification of 200-250 BP targets. In an effort to recover and detect only antigenically functional virions containing genomic RNA, antigen capture/RT-PCR was applied to UV irradiated viruses. No significant decrease in AC/RT-PCR titer was observed for all three viruses, despite extensive inactivation of the infectivity of MS2 and PV1. Amplicon length was increased to 500-1300 BP in an effort to improve detection of UV damage. The increase in amplicon size better estimated PV1 inactivation and detected greater inactivation at lower doses for NV. The results of this study indicate that RT-PCR amplification at multiple genomic sites and antigen-capture RT-PCR using polyclonal antibodies are not reliable methods to quantify the inactivation of viruses by UV radiation. However, amplification of longer RNA genomic targets may improve the ability of RT-PCR to predict reduction of virus infectivity by UV radiation.Master of Science in Public Healt

Investigating stock structure and trophic relationships among island-associated dolphins in the oceanic waters of the North Atlantic using fatty acid and stable isotope analyses

Short-beaked common dolphins (Delphinus delphis) and Atlantic spotted dolphins (Stenella frontalis) are the two most abundant cetacean species in the oceanic waters of Madeira and the Azores. They are of similar size, occur in similar habitats and are regularly observed in mixed-species groups to forage together. Genetic analyses suggested that, within each species, dolphins ranging around both archipelagos belong to the same panmictic population. We tested the hypotheses that (1) within each species, individuals from the two archipelagos belong to a single ecological stock; (2) between species, common and spotted dolphins have distinct trophic niches; using fatty acid (FA) and stable isotope (SI) analyses. Fatty acids and stable isotopes were analysed from 86 blubber and 150 skin samples of free-ranging dolphins, respectively. Sex-related differences were not significant, except for common dolphin FA profiles. In S. frontalis, FA and SI differences between archipelagos suggested that individuals belonged to different ecological stocks, despite the existence of gene flow between the two archipelagos. In D. delphis, differences were more pronounced, but it was not possible to distinguish between stock structure and a seasonal effect, due to differential sampling periods in the Azores and Madeira. Inter-specific comparisons were restricted to the Azores where all samples were collected during summer. Differences in FA proportions, noticeably for FA of dietary origin, as well as in nitrogen SI profiles, confirmed that both species feed on distinct resources. This study emphasizes the need for an integrated approach including both genetic and biochemical analyses for stock assessment, especially in wide-ranging marine top predators

Proceedings Of The 23Rd Paediatric Rheumatology European Society Congress: Part Two

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