An A-ELISA to detect hepatitis A virus in estuarine samples

Occurrence of Hepatitis A Virus in Water Matrices: A Systematic Review and Meta-Analysis

Hepatitis A is a common form of viral hepatitis. It is usually transmitted through the ingestion of contaminated food and water. This systematic review was carried out to summarise the overall prevalence of Hepatitis A virus (HAV) in different water matrices: untreated and treated wastewater, surface water, groundwater, drinking water, and others (e.g., irrigation water and floodwater). The literature search was performed in four databases: PubMed, Web of Science, Global Index Medicus, and Excerpta Medica Database. Heterogeneity (I2) was assessed using the χ2 test on the Cochran Q statistic and H parameters. A total of 200 prevalence data from 144 articles were included in this meta-analysis. The overall prevalence of HAV in water matrices was 16.7% (95% CI: 13.4−20.3). The prevalence for individual matrix was as follows: 31.4% (95% CI: 23.0−40.4) untreated wastewater, 18.0% (95% CI: 9.5−28.2) treated wastewater, 15.0% (95% CI: 10.1−20.5) surface water, 2.3% (95% CI: 0.1−6.0) in groundwater, 0.3% (95% CI: 0.0−1.7) in drinking water, and 8.5% (95% CI: 3.1−15.6) in other matrices. The prevalence was higher in low-income economies (29.0%). Africa and Eastern Mediterranean were the regions with higher HAV prevalence values. This study showed a high heterogeneity (I2 > 75%) with a significant publication bias (p value Egger test < 0.001). The results of this review suggest that water matrices could be an important route of HAV transmission even in industrialized countries, despite the lower prevalence compared to less industrialized countries, and the availability of advanced water management systems. More effective water/wastewater treatment strategies are needed in developing countries to limit the environmental circulation of HAV.

Review on the contamination of wastewater by COVID-19 virus: Impact and treatment

Emerging viruses are a major public health problem. Most zoonotic pathogens originate in wildlife, including human immunodeficiency virus (HIV), influenza, Ebola, and coronavirus. Severe acute respiratory syndrome (SARS) is a viral respiratory illness caused by a coronavirus called SARS-associated coronavirus (SARS-CoV). Viruses are charged colloidal particles that have the ability to adsorb on surfaces depending on pH. Their sorptive interaction with solid particles has important implications for their behavior in aquatic environments, soils, sewage sludge, and other solid materials and their removal or concentration by water treatment processes. Current state of knowledge on the potential of wastewater surveillance to understand the COVID-19 pandemic is reviewed. This study also identified wastewater irrigation systems with a higher risk of COVID-19 transmission. Emphasis was placed on methodologies for the detection and quantification of SARS-CoV-2 in wastewater.

16 Methods for Detecting Microbial Pathogens in Food and Water

Newly developed methods for the detection of bacteria and viruses have provided microbiologists with the means to rapidly identify and monitor specific microorganisms in food and water. Traditional methods of testing involve culture techniques to increase the numbers of the organism to a detectable level, followed by isolation and biochemical identification. This chapter focuses on the methodologies to detect pathogens and indicator organisms; however, the methods described are applicable to most bacteria. As detection and isolation methods have improved, a growing number of pathogens have been identified as important food- and waterborne pathogens. This chapter describes the use of nucleic acid and antibody probes that have the potential to circumvent the need to culture the organism prior to identification. Nucleic acid probes have become a valuable diagnostic reagent in the identification of human and animal pathogens and have made possible the identification of viruses and bacteria that are difficult, if not impossible, to cultivate. DNA probes have also proved to be a useful tool for identifying and monitoring the organisms in food and the environment.

The occurrence of hepatitis A and astroviruses in selected river and dam waters in South Africa

Over a period of one year (June 1997-May 1998) samples of surface waters, used for domestic and recreational purposes, were collected weekly from the same sites on the Klip River and Vaal Dam, Gauteng, South Africa. Sensitive and specific reverse transcriptase-polymerase chain reaction-oligonucleotide probe assays were used to detect HAV and HAstV RNA in concentrates of the water and infectious virus in cell cultures infected with the water concentrates. HAV was detected in 18 (35.3%) of the river and 19 (37.3%) of the dam water samples, often in association with the RNA from other enteric viruses. HAstV was detected less frequently and was present in 11 (21.6%) of the river and 3 (5.9%) of the dam water samples. A seasonal pattern was noted for HAV but not for HAstV. Cell culture amplification in a variety of carefully selected cell culture systems enhanced the detection of both viruses. Infectious viruses were detected in dam water samples where microbiological indicators of faecal pollution were absent or within acceptable limits. The presence of these viruses in the dam and river water could pose a potential health risk for people using these waters for domestic or recreational purposes.

Infectivity titration of the fast-replicating and cytopathic hepatitis A virus strain HM175A.2 by an in situ enzyme immunoassay

A simple, rapid and objective infectivity assay based on an in situ enzyme immunoassay (EIA) was developed for the fast-growing and cytopathic cell culture-adapted hepatitis A virus (HAV) strain HM175A.2. Infectivity titration by EIA correlated well with titration by cytopathic effects. The reliability of this assay was demonstrated by close agreement in virus infectivity titers among different assays of the same virus aliquot and between assays of different virus aliquots. HAV infected cell cultures after fixation could be stored for up to 1 week before testing without decline in virus titer.

A new method of RNA preparation for detection of hepatitis A virus in environmental samples by the polymerase chain reaction

A new method based on RNA preparation from shellfish by polyethylene glycol (PEG) precipitation and trichloroacetic acid (TCA) extraction was developed for the detection of hepatitis A virus (HAV) by the polymerase chain reaction (PCR). The extraction provides high yield and the extracted RNA is undegraded. This method proved to be particularly useful for detection of RNA viruses from environmental samples by PCR.

Depuration of Mytilus galloprovincialis experimentally contaminated with hepatitis A virus

Mussels (Mytilus galloprovincialis) were contaminated with known amounts of laboratory strains of hepatitis A virus and Poliovirus 1 and the effectiveness of a self-cleansing mechanism was studied using a pilot depuration system. Both viruses were rapidly bioaccumulated by mussels and the maximal concentration of about 10(4) TCID50/ml was reached within 1.5 hours. Depuration was carried out up to 24 h; infectivity titer decreased to 10(2) TCID50/ml and 10(3.2) TCID50/ml within 6 h in hepatitis A virus and Poliovirus 1 contaminated mussels, respectively, but only a very slight further decrease was obtained after 24 h. E. coli was used as a control; within 24 h the concentration decreased from 40 to 2 bacteria/ml of mussel (MPN). The elimination of bacteria is not a reliable parameter to control the effectiveness of viral depuration.

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.

Polyethylene glycol precipitation for recovery of pathogenic viruses, including hepatitis A virus and human rotavirus, from oyster, water, and sediment samples

Polyethylene glycol 6000 precipitation was found to be an effective concentration method that enhanced the chances for detecting human virus pathogens in environmental samples. Percent recoveries from eluates of fresh and estuarine waters with 8% polyethylene glycol 6000 averaged 86 for hepatitis A virus, 77 for human rotavirus Wa, 87 for simian rotavirus SA11, and 68 for poliovirus. Percent recoveries of 97, 40, 97 and 105, respectively, for the same viruses were obtained from oyster eluates by the same procedure. Percent recoveries of 97 for hepatitis A virus and 78 for human rotavirus Wa were obtained from sediment eluates containing 2 M NaNO3 with a final concentration of 15% polyethylene glycol 6000. The polyethylene glycol method was shown to be more effective than the organic flocculation method for recovery of hepatitis A virus and rotaviruses Wa and SA11, but not of poliovirus 1 in laboratory studies. In field trials, hepatitis A virus or rotavirus or both were recovered from 12 of 18 eluates by polyethylene glycol, compared with recovery from 9 of 18 eluates by organic flocculation from fresh and estuarine waters subject to pollution.

Production of cytopathology in FRhK-4 cells by BS-C-1-passaged hepatitis A virus

Cytopathic effects were produced in fetal rhesus monkey kidney (FRhK-4) cells 7 days postinfection by a serially BS-C-1-passaged strain of hepatitis A virus. Typical enterovirus cytopathology was produced by the HM-175 strain after 15 passages at 7-day intervals in BS-C-1 cells. No cytopathic effects were obtained after neutralization of virus with human anti-hepatitis A virus immunoglobulin G. Normal human serum had no effect on development of cytopathology. Maximum antigen and cDNA probe-based hybridization activity were associated with a CsCl gradient fraction having a density of 1.34 g/cm3. Large quantities of 27- to 30-nm virions typical of hepatitis A virus were associated with the same fraction. These data led to the conclusion that the observed cytopathology was caused by hepatitis A virus.

Detection of hepatitis A virus by hybridization with single-stranded RNA probes

An improved method of dot-blot hybridization to detect hepatitis A virus (HAV) was developed with single-stranded RNA (ssRNA) probes. Radioactive and nonradioactive ssRNA probes were generated by in vitro transcription of HAV templates inserted into the plasmid pGEM-1. 32P-labeled ssRNA probes were at least eightfold more sensitive than the 32P-labeled double-stranded cDNA counterparts, whereas biotin-labeled ssRNA probes showed a sensitivity comparable with that of the 32P-labeled double-stranded cDNA counterparts. Hybridization of HAV with the ssRNA probes at high stringency revealed specific reactions with a high signal-to-noise ratio. The differential hybridization reactions seen with probes of positive and negative sense (compared with HAV genomic RNA) were used to detect HAV in clinical and field samples. A positive/negative ratio was introduced as an indicator that permitted a semiquantitative expression of a positive HAV reaction. Good agreement of this indicator was observed with normal stool samples and with HAV-seeded samples. By using this system, HAV was detected in estuarine and freshwater samples collected from a sewage-polluted bayou in Houston and a saltwater tributary of Galveston Bay.