Christon J. Hurst

Survival of the enteric adenoviruses 40 and 41 in tap, sea, and waste water

Abstract The enteric adenoviruses types 40 (Ead 40) and 41 (Ead 41) have emerged as a leading cause of viral gastroenteritis in children, second in importance only to the rotaviruses. The role of the enteric adenoviruses as waterborne pathogens has not been evaluated. This study compared the survival of these agents with poliovirus type 1 (polio 1) and the hepatitis A virus (HAV) in tap water at 4°C, and at room temperature, with polio 1 in primary and secondary wastewater at 4, and 15°C, and in sea water at 15°C. Assays were conducted at regular intervals by the TCID50 method in PLC/PRF/5 cells. The survival of Ead 40 and Ead 41 in primary and secondary wastewater was slightly greater than that of polio 1. However, in tap, and sea water, the enteric adenoviruses were substantially more stable than either polio 1 or HAV. These results suggest that the enteric adenoviruses may survive for prolonged periods in water, representing a potential route of transmission.

Coliphages as indicators of human enteric viruses in groundwater

Due to a lack of dependable routine methods for direct analysis of pathogenic microorganisms, tests for bacteria that are supposed to be of intestinal origin are used to indicate the presence and extent of fecal pollution in water. Current indicators are not accurate monitors of fecal pollution and do not adequately reflect the presence of human enteric viruses. Coliphages (viruses that infect the bacterium Escherichia coli which occurs in the feces of all warm‐blooded animals) have been proposed as indices of water quality. Coliphages are readily recovered from sewage from all parts of the world. In most cases, the persistence of coliphages in surface waters, groundwaters, and sewage is greater than that of human enteric viruses and enteric bacteria. Coliphages have a number of unique characteristics which permit selective analytical techniques. On the basis of these techniques, a system for predicting the presence of human enteric viruses in groundwater can be developed.

Fate of viruses during wastewater sludge treatment processes

Infectious viruses are shed from humans by many routes. These include coughing and sneezing, contact with and aerosolization from external body lesions, urinary and intestinal excretions. Viruses shed by the latter two routes, urinary and intestinal excretions, are likely to be present as contaminants in domestic wastewater. The purpose of this review is to summarize recent information on the pathways which viruses follow during wastewater sludge‐generation processes and to examine information pertinent to the fate of viruses during wastewater sludge disposal. Information is included on viruses capable of causing human illness, as well as on bacterial viruses also present in wastewater, which, in some ways, may serve as indicators when assessing the likely fate of human viruses.

Comparison of cytopathogenicity, immunofluorescence and in situ DNA hybridization as methods for the detection of adenoviruses

Abstract Three different methods were compared for their efficiency at detection of adenoviruses. The samples examined for viral analysis consisted of concentrates prepared from raw sewage, chosen as providing a representation of the spectrum of viruses being intestinally shed from a large population at any given time. When using one single cell line, HEp-2, the overall numbers of adenoviruses detected using cytopathogenicity and immunofluorescence were roughly equal. In situ hybridization was approx. 40% more sensitive than either of these other methods as determined by average virus titers for the different samples, and also proved to be better by means of a nonparametric comparison. The 293 cell line was approx. 5 times more sensitive for detecting adenoviruses by cytopathogenicity as compared with the HEp-2 cell line, but proved unsuitable in our hands for quantitatively detecting indigenous adenoviruses by immunofluorescence. The relative number of indigenous adenoviruses present in the sewage concentrates we examined was, on average, 94-fold greater than that of enteroviruses. Assay of enteroviruses was performed by plaque assay in the BGM cell line.

Type and strain dependence of enterovirus adsorption to activated sludge, soils and estuarine sediments

Abstract The degree of enterovirus adsorption to surfaces was found to be both type- and strain-dependent.

Detection of environmental viruses in sludge: Enhancement of enterovirus plaque assay titers with 5-iodo-2′-deoxyuridine and comparison to adenovirus and coliphage titers

Abstract Enteroviruses present in the primary sludge of two wastewater treatment plants were quantitated by plaque assay using a continuous African green monkey kidney cell line (BGM). Incubation of BGM monolayers with 5-iodo-2′-deoxyuridine (50 μg ml−1) for 4 days prior to use enhanced the number of PFU detected in 10 of 10 concentrated sludge samples. Coliphages also present in these samples were detected using as hosts E. coli C and E. coli A-19, an Hfr strain. E. coli C coliphage titers were consistantly higher than E. coli A-19 titers, and were 102-103 times higher than the enterovirus titers obtained with BGM cells. Adenoviruses present in the sludge samples were detected by immunofluorescence assay. Interestingly, those results suggested that adenoviruses were also more numerous than enteroviruses (as detected by either IDU-treated or untreated BGM plaque assay).

Detecting Viruses in Water

Various and divergent approaches that have been used to concentrate and assay viruses from tap water and environmental freshwaters are summarized and briefly explained. The basic principles behind the different methodologies and descriptions of the most recent developments are emphasized. Comparisons help demonstrate the relative sensitivities of different concentration and assay techniques.

2 – An Introduction to Viral Taxonomy and the Proposal of Akamara, a Potential Domain for the Genomic Acellular Agents

This chapter introduces viral taxonomy and the proposal of akamara, which is a potential domain for the genomic acellular agents. This chapter also introduces the idea that the taxonomy of the viruses and their biological relatives could be extended to the domain level. There currently exist three biological domains, archaea, bacteria, and eukarya, that consist only of cellular organisms. The establishment of these three existing domains and the taxonomic placement of biological entities within them are based largely on the ribosomal RNA nucleotide sequence of those constituent organisms. This chapter proposes the creation of an additional biological domain that would represent the acellular infectious agents that possess nucleic acid genomes. The proposed constituents of this domain are the agents commonly termed to be either viruses, satellite viruses, virusoids, or viroids. The proposed domain title is Akamara. A possible organizational structure within this proposed new domain is also suggested, with its occupants being divided into two kingdoms: plus phyla and classes premised on the basic characteristics of the genomic biochemistry of the organisms.

Improved method for recovery of enteric viruses from wastewater sludges

Abstract Various parameters involved in recovering indigenous enteric viruses from wastewater sludges aided by buffered beef extract elution and subsequent organic flocculation concentration were examined. A statistically significant ( P =0.03) reciprocal correlation was found to exist between the ratio of eluant to sludge solids content used during the elution step, and the efficiency of subsequently concentrating viruses from the produced sludge eluates by means of organic flocculation. A hypothesis is proposed by which to explain the concentration of viruses during beef extract-induced organic flocculation.

Suppression of viral replication by guanidine: a comparison of human adenoviruses and enteroviruses

A comparison was made between the relative sensitivities of laboratory strain human adenoviruses and enteroviruses, and recently isolated human enteroviruses, to the presence of guanidine hydrochloride in cell culture media. The concentration of guanidine hydrochloride used was 100 micrograms per ml. Representatives of all six human Adenovirus subgenera were unaffected in their replication at this concentration of guanidine. The different human Enterovirus types examined varied in their sensitivity, with suppression ranging from less than 1 to 3 log10 units for laboratory strains, and from 2 to 7 log10 units for recently isolated viruses. The findings suggest a novel role for antiviral drugs; serving as an adjunct in facilitating selective isolation of specific virus groups which may be present as part of mixed viral populations.