| Many virus-related infectious diseases can be transmitted through water or sewage,which has severely threatened human health,and great concerns has been focused on virological safety of wastewater. Hitherto, there is no effective method for concentrating virus from sewage directly, and the limit conclusions about virus disinfection principles and mechanisms were different, even controversial. In this study, we aimed at developing an effective methods for virus concentration from sewage, and analyzing the impacts of sewage quality on disinfection by Cl2 and ClO2, and finding better microbial indicators for sewage disinfection; we also try to elucidate the mechanisms of virus inactivation by Cl2 and ClO2 on the level of nucleotide acid and proteins functions, thus to ensure the safety of wastewater disinfection.Based on the existed virus-concentrating method with positively charged filter in our laboratory, we added poly aluminum chloride (PAC) to sewage to 30mg/L, and adjusted sewage pH value to 6.5, we obtained excellent recovery rate of more than 80% under 20-30℃.Disinfection of sewage by Cl2 and ClO2 were performed under different COD, NH4+-N, chromaticity, turbidity, pH value and temperatures. Results showed that ClO2 was superior to Cl2; COD, chromaticity and turbidity had negative influence on both disinfectants. NH4+-N inhibited the Cl2 disinfection but had no effect on that of ClO2; higher temperature benefit disinfection for both disinfectants; The overall resistance of different microorganisms were ranked as below: PV1> f2 > S. faecalis> S.typhimurium> C.perfringens>E.coli. We advise that S. faecalis can be used as bacterial indicator, and f2 bacteriophage as viral indicator to evaluation of the disinfection Cl2 and ClO2.PV1 was processed by different doses of Cl2 (0.1, 0.5, 1.0, 1.5 and 2.0mg/L) and ClO2 (0.1, 0.2, 0.4, 0.8 and 1.2mg/L) over different times, then cell culture, ELISA (enzyme linked-immunosorbent assay), PCR and nucleotide acid hybridization were carried out to study the mechanisms of virus inactivation by Cl2 and ClO2. It showed that Cl2 and ClO2 inactivated PV1 mainly by damaging 5'-NCR of its genome, and damage of viral capsid was not related to viral inactivation; Cl2 damage poly A tail firstly, and then the 3'-NCR, but ClO2 inactivate PV1 by damaging 5'-NCR directly; Oligonucleotide probes of about 50 and 18nt were used in turn to located the damaged sites; It showed that damaged sites by Cl2 located in 60-80, 234-274, 300-317 and 483-501nt regions within PV1 genome, and those by ClO2 in 124-143, 300-317, 334-350 and 581-599nt regions; genome models with corresponding damaged sites were constructed successfully with PCR, PV1 genomes with the impaired 5'-NCR had no infectivity, and those without 3'-NCR and/or poly A tail, or with impaired poly A tail had greatly decreased infectivity.CCC-ELISA(combined cell culture-enzyme linked immunosorbent assay), ELISA and nucleotide acid hybridization were used to study the adhering, penetrating and uncoating ability of disinfectant-inactivated PV1 with integrate antigenicity. Results indicated that Cl2 and ClO2-inactivated PV1 with integrate antigenicity still had the ability of adherence, penetration, Cl2-inactivated PV1 with integrate antigenicity could uncoat, but it was not for ClO2-inactivated PV1.In this study, the main results are as follows:1. Reliable and simple method for viral recovery from sewage had been established,with which more than 80% of virus could be recovered from large volume of 20L sewage.2. ClO2 was superior to Cl2 for wastewater disinfection, water quality could influence the disinfection by Cl2 and ClO2, and we advise that S. faecalis can be used as bacterial indicator, and f2 bacteriophage as viral indicator to evaluation of the disinfection Cl2 and ClO2.3. Damage of 5'-NCR by Cl2 and ClO2 mainly responsible for inactivating PV1;4. Viral ability of intrusion into cell could be stripped by Cl2 and ClO2, different from ClO2 ,Cl2-inactivated PV1 capsid still had the function of uncoating.
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