Human noroviruses in the faeces of wild birds and rodents-new potential transmission routes

Human noroviruses (HuNoVs) are one of the leading global causes of diarrhoeal diseases and are transmitted mainly from person to person but also through contaminated food, water and fomites. The possible zoonotic nature of NoVs has occasionally been discussed, although the viruses are generally considered to be host-species-specific. We investigated whether wild birds and rodents could serve as carriers of HuNoVs, thereby transmitting the virus to humans directly or indirectly by contaminating foods. All samples, 115 avian and 100 rat faeces collected in springs 2009-2013 from dump sites, and 85 faeces from yellow-necked mice trapped in late autumn 2008 and 2009 after the rodents entered human settlements due to the first night frosts, were screened for HuNoV using real-time reverse transcription PCR. HuNoVs were detected in 31 (27%) faecal samples of wild birds, in two (2%) faecal samples of rats and in no samples of mice. Most (25) of the positive bird samples and both rat samples contained genogroup II, and six positive bird samples contained genogroup I HuNoV. The avian species shedding faeces containing HuNoVs were identified as gulls and crows using DNA barcoding. Our results show that wildlife, birds and rats in particular, is capable of spreading HuNoVs in the environment.

Virological Quality of Irrigation Water in Leafy Green Vegetables and Berry Fruits Production Chains

This study condenses data acquired during investigations of the virological quality of irrigation water used in production of fresh produce. One hundred and eight samples of irrigation water were collected from five berry fruit farms in Finland (1), the Czech Republic (1), Serbia (2), and Poland (1), and sixty-one samples were collected from three leafy green vegetable farms in Poland, Serbia, and Greece. Samples were analyzed for index viruses of human or animal fecal contamination (human and porcine adenoviruses, and bovine polyoma viruses), and human pathogenic viruses (hepatitis A virus, hepatitis E virus, and noroviruses GI/GII). Both index and pathogenic viruses were found in irrigation water samples from the leafy green vegetables production chain. The data on the presence of index viruses indicated that the highest percentage of fecal contamination was of human origin (28.1 %, 18/64), followed by that of porcine (15.4 %, 6/39) and bovine (5.1 %, 2/39) origins. Hepatitis E virus (5 %, 1/20) and noroviruses GII (14.3 %, 4/28) were also detected. Samples from berry fruit production were also positive for both index and pathogenic viruses. The highest percentage of fecal contamination was of human origin (8.3 %, 9/108), followed by that of porcine, 4.5 % (4/89) and bovine, 1.1 % (1/89) origins. Norovirus GII (3.6 %, 2/56) was also detected. These data demonstrate that irrigation water used in primary production is an important vehicle of viral contamination for fresh produce, and thus is a critical control point which should be integrated into food safety management systems for viruses. The recommendations of Codex Alimentarius, as well as regulations on the use of water of appropriate quality for irrigation purposes, should be followed.

Hepatitis E Virus Antibodies in Finnish Veterinarians

We investigated hepatitis E virus (HEV) infections in Finnish veterinarians engaged in different practice specialties and evaluated the effect of different background factors on HEV exposure by examining total HEV antibodies in samples collected from the participants of the 2009 National Veterinary Congress in Helsinki, Finland. Finnish veterinarians commonly have total HEV antibodies with seroprevalence of 10.2%. Of the non-veterinarians, 5.8% were seropositive. Increasing age was associated with HEV seropositivity, and, surprisingly, the highest HEV seroprevalence (17.8%) among veterinarians was detected among small animal practitioners. Although no positive correlation between swine contacts and HEV seropositivity was found, 22.7% of veterinarians who had had needle stick by a needle that had previously been injected into a pig versus 9.0% of those who had not were seropositive, even though the finding was statistically non-significant (P = 0.07). Our results suggest that, although contact with swine is a known risk factor for HEV infection, the sources of HEV infections are probably numerous, including travelling abroad and possibly also other reservoirs of HEV than pigs.

Ultraviolet Light Inactivation of Murine Norovirus and Human Norovirus GII: PCR May Overestimate the Persistence of Noroviruses Even When Combined with Pre-PCR Treatments

Transmission of gastroenteritis-causing noroviruses may be significant via contaminated surfaces. Measures for control, e.g. disinfection with ultraviolet irradiation (UV), are therefore necessary for interrupting this transmission. Human norovirus (HuNoV) GII.4 and Murine norovirus (MuNoV) were used to study the efficacy of UV for virus inactivation on dry glass surfaces. MuNoV inactivation was measured using viability assay and the reduction in viral RNA levels for both viruses using reverse transcription quantitative PCR (RT-QPCR). For each UV dose, two parallel sample groups were detected using RT-QPCR: one group was enzymatically pre-PCR treated with Pronase and RNAse enzymes, while the other was not treated enzymatically. In the viability assay, loss of infectivity and a 4-log reduction of MuNoV were observed when the viruses on glass slides were treated with a UV dose of 60 mJ/cm(2) or higher. In the RT-QPCR assay, a steady 2-log decline of MuNoV and HuNoV RNA levels was observed when UV doses were raised from 0 to 150 mJ/cm(2). A distinct difference in RNA levels of pretreated and non-pretreated samples was observed with UV doses of 450-1.8 × 10(3) mJ/cm(2): the RNA levels of untreated samples remained over 1.0 × 10(3) PCR units (pcr-u), while the RNA levels of enzyme-treated samples declined below 100 pcr-u. However, the data show a prominent difference between the persistence of MuNoV observed with the infectivity assay and that of viral RNA detected using RT-QPCR. Methods based on genome detection may overestimate norovirus persistence even when samples are pretreated before genome detection.

A longitudinal study revealing hepatitis E virus infection and transmission at a swine test station

Hepatitis E virus (HEV) is a zoonotic agent that causes acute hepatitis in humans, and infects several animal species, most importantly swine. In the current study, that presents the first evidence of HEV infections in pigs in Finland, genetic divergence and transmission of HEV was investigated among pigs at a swine test station at two occasions. In 2007, HEV RNA was found in 25% of pens, and 35% of 2-3 month-old pigs at the station. Three different isolates, comprising 13 sequences of HEV genotype 3 e that were imported from different farms were detected. In 2010, 39% of pigs were HEV RNA positive on weeks 1, 3, or 5 of a 3-month follow-up, and 11 sequences, all representing one of the isolates that was also present in 2007, were detected. The isolate was considered to be either re-introduced to, or to persist at the station, and it was transmitted between the pigs. The study sheds light on the rate and time of HEV transmission in swine, and describes the epidemiologic variability of HEV isolates over time.

Detection of human norovirus from frozen raspberries in a cluster of gastroenteritis outbreaks

We describe a cluster of norovirus outbreaks affecting about 200 people in Southern Finland in September and October 2009. All outbreaks occurred after consumption of imported raspberries from the same batch intended for the catering sector. Human norovirus genotype GI.4 was found in frozen raspberries. The berries were served in toppings of cakes in separate catering settings or mixed in curd cheese as a snack for children in a daycare center. The relative risk for consumption of the berry dish was 3.0 (p <or= 0.05) at the daycare centre. Human norovirus GI.4 was also detected in samples from two patients, and in berries. Both shared identical partial capsid sequences. Based on the results of epidemiological, trace-back and laboratory investigations it was concluded that one particular batch of frozen raspberries was the source of all outbreaks.

Detection of human norovirus from frozen raspberries in a cluster of gastroenteritis outbreaks

We describe a cluster of norovirus outbreaks affecting about 200 people in Southern Finland in September and October 2009. All outbreaks occurred after consumption of imported raspberries from the same batch intended for the catering sector. Human norovirus genotype GI.4 was found in frozen raspberries. The berries were served in toppings of cakes in separate catering settings or mixed in curd cheese as a snack for children in a daycare center. The relative risk for consumption of the berry dish was 3.0 (p ≤ 0.05) at the daycare centre. Human norovirus GI.4 was also detected in samples from two patients, and in berries. Both shared identical partial capsid sequences. Based on the results of epidemiological, trace-back and laboratory investigations it was concluded that one particular batch of frozen raspberries was the source of all outbreaks.

Potential internalisation of caliciviruses in lettuce

Fresh produce such as lettuce (Lactuca sativa) has often been linked to epidemic viral gastroenteritis. In these cases, it is unknown whether the viral contamination has occurred during the growing or the processing of the implicated product. In this study lettuce was grown in the presence of enteric viruses, and the uptake of viruses via the roots into the edible parts (leaves and stem) of the lettuce plants was investigated, for plants with both intact and damaged roots. The roots of lettuce, growing either in hydroponic culture or in soil, were exposed to canine calicivirus (CaCV) and a human genogroup 2 norovirus (HuNoV) by these being added into the water or soil in which the lettuce was growing. Leaves from lettuce plants and seedlings were examined for viruses by real-time RT-PCR. When the lettuce plants were exposed to very high concentrations of CaCV, the virus was detected in lettuce leaves, indicating contamination via the roots, but the frequency of positive results was low. Internalisation occurred in both seedlings and grown plants, in both hydroponic and soil cultures, and occurred whether the roots were intact or damaged. However, internalisation of HuNoV was not detected in any of the experimental set ups, although the concentrations to which the plants were exposed were relatively high. Based on these results, viral contamination of lettuce plants via roots cannot be excluded, but is apparently not an important transmission route for viruses.

Data quality of 5 years of central norovirus outbreak reporting in the European Network for food-borne viruses

BACKGROUND

The food-borne viruses in Europe (FBVE) network database was established in 1999 to monitor trends in outbreaks of gastroenteritis due to noroviruses (NoVs), to identify major transmission routes of NoV infections within and between participating countries and to detect diffuse international food-borne outbreaks.

METHODS

We reviewed the total of 9430 NoV outbreak reports from 13 countries with date of onset between 1 January 2002 and 1 January 2007 for representativeness, completeness and timeliness against these objectives.

RESULTS

Rates of reporting ranged from a yearly average of 1.8 in 2003 to 11.6 in 2006. Completeness of reporting of an agreed minimum dataset improved over the years, both for epidemiological and virological data. For the 10 countries that provided integrated (epidemiological AND virological) reporting over the 5-year period, the completeness of the minimum dataset rose from 15% in 2003 to 48% in 2006. Two countries have not been able to combine both data types due to the structure of the national surveillance system (England and Wales and Germany). Timeliness of reporting (median days between the onset of an outbreak and the date of reporting to the FBVE database) differed greatly between countries, but gradually improved to 47 days in 2006.

CONCLUSION

The outbreaks reported to the FBVE reflect the lack of standardization of surveillance systems across Europe, making direct comparison of data between countries difficult. However, trends in reported outbreaks per country, distribution of NoV genotypes, and detection of diffuse international outbreaks were used as background data in acute questions about NoV illness and the changing genotype distribution during the 5-year period, shown to be of added value. Integrated reporting is essential for these objectives, but could be limited to sentinel countries with surveillance systems that allow this integration. For successful intervention in case of diffuse international outbreaks, completeness and timeliness of reporting would need to be improved and expanded to countries that presently do not participate.

Norovirus genotypes causing gastroenteritis outbreaks in Finland 1998–2002

BACKGROUND

Outbreak investigation methods for enteric viruses were improved in 1990s when gene amplification techniques were established in viral laboratories.

OBJECTIVES

The objective of the study was to determine the causative agents for Finnish viral gastroenteritis outbreaks. Our aim was also to further characterise the norovirus strains, reveal the temporal occurrence of norovirus (NV) genotypes and to study some epidemiological aspects concerning the outbreaks.

STUDY DESIGN

A total of 416 Finnish viral gastroenteritis outbreaks that occurred during 5 years (1998-2002), excluding those among hospitalised children, were investigated for enteric viruses. Stool samples were screened by electron microscopy as well as analyzed by specific noro- and astrovirus RT-PCR tests. Amplicon sequence analysis was used to find out norovirus genotypes.

RESULTS

Noroviruses caused 252 (60.6%) of the outbreaks; other viruses, astro- or rotavirus, caused four epidemics. Norovirus epidemics occurred in all kinds of settings, most often in hospitals (30.6%) and in restaurants and canteens (14.3%). Both NV genogroups were found every year, but NV GGII outbreaks always outnumbered those of GGI. All but one outbreak at hospitals and nursing homes were of genotype GII. Polymerase sequence analysis revealed a variety of NV genotypes; six GI and at least eight GII genotypes. The GI.3 Birmingham-like and GII.4 Bristol-like genotype appeared every year, whereas the other types were circulating for shorter periods or sporadically. During the study period the genotypes GII.4 (Bristol), GII.1 (Hawaii), an emerging genotype GIIb, and a new variant of GII.4 predominated in that order. Indication for rapid genetic changes in the genotype GII.4 was also noticed.

CONCLUSIONS

Noroviruses were the most prevalent causative agents in the outbreaks. Many NV genotypes were circulating, and a shift in the predominant genotypes was evident between epidemic seasons.

Wading pool water contaminated with both noroviruses and astroviruses as the source of a gastroenteritis outbreak

In July 2001, an outbreak of gastroenteritis occurred in Helsinki among children and adults after bathing in an outdoor wading pool. The epidemiological survey revealed that at least 242 persons were affected. Microbiological testing of both patient stool samples and of the pool water revealed the presence of two different gastroenteritis viruses: a norovirus (NV) and an astrovirus. Amplicon sequencing of the NV samples showed nucleotide sequence identity between the virus from patients and the water. After changing the pool water and the sand at the bottom of the pool followed by shock chlorination, no virus could be detected in the water. However, NV was continuously detected in the water outlet well as much as 8 months after the incident. Here we show how molecular methods aided in tracing the source of the epidemic and in finding the causative pathogens both in patients and in the environment.

Evaluation of the purification capacity of nine portable, small-scale water purification devices

A test was performed to evaluate the microbial and chemical purification capacity of nine portable, small-scale water purification filter devices with production capacity less than 100 L/h. The devices were tested for simultaneous removal capacity of bacteria (cultured Escherichia coli, Clostridium perfringens, Klebsiella pneumoniae and Enterobacter cloacae), enteric protozoans (formalin-stored Cryptosporidium parvum oocysts), viral markers (F-RNA bacteriophages) and microcystins produced by toxic cyanobacterial cultures. In general, the devices tested were able to remove bacterial contaminants by 3.6-6.9 log10 units from raw water. Those devices based only on filtration through pores 0.2-0.4 microm or larger failed in viral and chemical purification. Only one device, based on reverse osmosis, was capable of removing F-RNA phages at concentrations under the detection limit and microcystins by 2.5 log10. The present study emphasised the need for evaluation tests of water purification devices from the public safety and HACCP (Hazard Analysis and Critical Control Point) points of view. Simultaneous testing for various pathogenic/indicator microbes and microcystins was shown to be a useful and practical way to obtain essential data on actual purification capacity of commercial small-scale drinking-water filters.

A prolonged outbreak of Norwalk-like calicivirus (NLV) gastroenteritis in a rehabilitation centre due to environmental contamination

An outbreak of Norwalk-like calicivirus (NLV) gastroenteritis occurred in a rehabilitation centre in southern Finland between December 1999 and February 2000. An epidemiological investigation was conducted to determine the source and extent of the outbreak. More than 300 guests and staff members became ill during the outbreak. No food or activity in the centre could be linked epidemiologically to illness. NLV genogroup II was detected by RT-PCR in stool samples of symptomatic guests and employees. All strains reacted similarly with the microplate hybridization probe panel and showed the same nucleotide sequence, indicating that they represented the same NLV strain. Food and water samples were negative for NLV, whereas NLV was detected in three environmental specimens. The strains from patients and environment were identical based on microplate hybridization probes, suggesting that environmental contamination may have been important for the spread of calicivirus and the protracted course of the outbreak.

Molecular epidemiology of viral pathogens and tracing of transmission routes: hepatitis-, calici- and hantaviruses

BACKGROUND

The need to rapidly identify new therapeutic drugs and vaccines for clinically important viral infections has resulted in intensive study of the molecular properties of viruses. Modern molecular techniques have provided tools for tracing infections and studying the evolution of viruses. OBJECTIVE STUDY AND DESIGN: Two examples illustrating how modern molecular techniques can be used in clinical virology and molecular epidemiology (hepatitis and caliciviruses), and one example documenting their importance in basic research (hantaviruses) will be discussed.

RESULTS AND CONCLUSIONS

Water- and food-borne outbreaks caused by the faeco-orally spread hepatitis A virus (HAV) are common in areas lacking proper sanitation, but they are possible also in countries with low seroprevalence. In water epidemics, the sequence comparisons between the virus from patients and from water have been used successfully. Hepatitis B virus variants are clinically important and challenge the diagnostic tests and prophylactic measures. Some hepatitis C (HCV) genotypes appear to be associated with more severe pathology and others respond better to antiviral treatment. Nosocomial and occupational infections are not rare, and the source can be identified by phylogenetic analysis of nucleotide sequences obtained from the infected individuals. The overwhelming role of Norwalk-like caliciviruses (NLV) in adult diarrhoea and especially in food- and water-borne epidemics has become apparent during the last decade. Methods are under development for detecting these viruses, not only from patient samples and water, but also from other environmental samples (e.g. foodstuff and surface swabs). The analysis of the genetic variation and evolution of the Old World hantaviruses in their carrier rodents has shown that the extent of genetic diversity correlates with geographical distance. As a rule, phylogenetic relationships of hantaviruses resemble those of their rodent hosts, suggesting virus-host co-evolution. Exceptional host-switch events allow a study on still radiating hantavirus species. There is suggestive evidence that natural reassortant hantaviruses are involved in human infection.

An outbreak of calicivirus associated with consumption of frozen raspberries

In April 1988, an outbreak of gastroenteritis occurred among employees in a large company in Helsinki, Finland. A retrospective cohort study, using a self-administered questionnaire, was carried out to ascertain the cause and extent of the outbreak. To meet the case definition, employees had to have had diarrhoea and/or vomiting since 2 April, 1998. A subanalysis was made in the biggest office, consisting of 360 employees, of whom 204 (57%) completed the questionnaire. Of these 108 (53%) met the case definition. Employees who had eaten raspberry dressing were more likely to meet the case definition than those who had not (Attack Rate (AR) 65% versus AR 18% Relative Risk, (RR) 3.7, 95%, Confidence Intervals (CI) 2.0-6.7). Four stool specimens obtained from affected kitchen staff who had all eaten the raspberry dressing and who had all become ill simultaneously with the employees were positive by polymerase chain reaction (PCR) for calicivirus. The data suggest that the primary source of the outbreak was imported frozen raspberries contaminated by calicivirus.

Outbreak of viral gastroenteritis due to drinking water contaminated by Norwalk-like viruses

Heinävesi, a Finnish municipality with a population of 4860 inhabitants, had an outbreak of gastroenteritis in March 1998. On the basis of an epidemiologic survey, an estimated 1700-3000 cases of acute gastroenteritis occurred during the outbreak. Municipal water consumption was found to be associated with illness (risk ratio [RR]=3.5, 95% confidence interval, 3.11>RR>3.96). Norwalk-like virus (NLV) genogroup II (GGII) was identified in untreated water, treated water, and 4 tap water samples by use of reverse transcription-polymerase chain reaction. This was the first time NLVs had been detected in municipal tap water. Fifteen of 27 patient stool samples had NLV GGII, with an identical amplification product to that found in the water samples, indicating that the outbreak was caused by this virus. In some patients, NLV genogroup I was also encountered. This virus, however, could not be detected in the water samples. Inadequate chlorination contributed to the survival of the virus in the water.

Confirmation of Norwalk-like virus amplicons after RT-PCR by microplate hybridization and direct sequencing

A large number of Norwalk-like viruses (NLVs) have been identified from stool samples by RT-PCR by amplifying part of the polymerase-coding gene. A set of probes were selected based on sequence analysis of the viruses circulating in Finland during the years 1996-97 for confirmation of the findings by hybridization. A microplate hybridization test, which provides a rapid semi-automatic detection for PCR products, was designed and compared with agarose gel electrophoresis. From the material of 210 stool samples, mainly from diarrheal outbreaks during years 1997-1998, three probes, one for NLV genogroup GGI and one for each of the two GGII subgroups (Toronto-like and Lordsdale-like), were sufficient to detect 87.8% (36/41) of GGI and 89.0% (49/55) of GGII samples positive by gel electrophoresis. Amplicon sequencing of the strains not detected by the above probes revealed genetic variability in the sequences. Biotin-streptavidin binding was used both for microplate hybridization assays and for direct sequencing to identify the amplicons. Based on the sequences three more probes for the hybridization panel were added so that all the different NLVs of this study could be recognized.

Prophylactic Lactobacillus GG reduces antibiotic-associated diarrhea in children with respiratory infections: a randomized study

OBJECTIVES

Antimicrobial treatment may disturb the colonization resistance of gastrointestinal microflora, which may induce clinical symptoms, most commonly diarrhea. The severity of antibiotic-associated diarrhea may range from a brief, self-limiting disease to devastating diarrhea with electrolyte disturbances, dehydration, crampy abdominal pain, pseudomembranous colitis, toxic megacolon, or even death. The incidence of diarrhea in children receiving a single antimicrobial treatment is unclear. In addition to more critical use of antimicrobials, adjunctive preventive measures to antibiotic-associated diarrhea are needed. The objective of this study was to evaluate the incidence of diarrhea after antimicrobial treatment in children with no history of antimicrobial use during the previous 3 months. Another aim of this study was to assess the preventive potential of Lactobacillus rhamnosus GG (Lactobacillus GG; American Type Culture Collection 53103), a probiotic strain with a documented safety record and a therapeutic effect in viral gastroenteritis on antibiotic-associated diarrhea.

METHODS

Oral antimicrobial agents were prescribed for the treatment of acute respiratory infections at the clinics of the Health Care Center of the City of Tampere or Tampere University Hospital, Finland, to 167 patients who were invited to participate in the study. Of the patients, 48 were lost to follow-up; therefore, the final study population consisted of 119 children from 2 weeks to 12. 8 years of age (mean: 4.5 years). All study subjects met the inclusion criteria: they had not received any antimicrobial medication during the previous 3 months, they did not suffer from gastrointestinal disorders, and they did not need intravenous antimicrobial treatment. The patients were randomized to receive placebo or 2 x 10(10) colony-forming units of Lactobacillus GG in capsules given twice daily during the antimicrobial treatment. Lactobacillus GG and placebo capsules were indistinguishable in appearance and taste. The parents kept a daily symptom diary and recorded stool frequency and consistency at home for 3 months. Diarrhea was defined as at least three watery or loose stools per day for a minimum of 2 consecutive days. In the case of diarrhea, viral (adenovirus, rotavirus, calicivirus and astrovirus) and bacterial (Salmonella, Shigella, Yersinia, Campylobacter, Clostridium difficile, Staphylococcus aureus, and yeasts) analyses were studied in fecal samples. The metabolic activity of the gut microflora was assessed by analysis of fecal urease, beta-glucosidase, and beta-glucuronidase activities. The primary outcome measure was diarrhea during the first 2 weeks after the beginning of the antimicrobial treatment, because this period most likely reflects the effects of antimicrobial use. Secondary outcome measures were the activities of fecal urease, beta-glucuronidase, and beta-glucosidase.

RESULTS

On the entire follow-up, 80% of any gastrointestinal symptoms were reported during the first 2 weeks after the beginning of the antimicrobial treatment. The incidence of diarrhea was 5% in the Lactobacillus GG group and 16% in the placebo group within 2 weeks of antimicrobial therapy (chi(2) = 3.82). The treatment effect (95% confidence interval) of Lactobacillus GG was -11% (-21%-0%). In diarrheal episodes, the viral and bacterial analyses were positive for Clostridium difficile in 2 cases and for Norwalk-like calicivirus in 3 cases. The age of the patients with diarrhea was between 3 months and 5 years in 75% of cases in both groups. The severity of diarrhea was comparable in the study groups, as evidenced by similar stool frequency (mean: 5 per day; range: 3-6) and the duration of diarrhea (mean: 4 days; range: 2-8). The activities of fecal urease and beta-glucuronidase, but not beta-glucosidase, changed significantly after the beginning of the antimicrobial treatment in the Lactobacillus GG group and in the placebo group alike. (ABSTRACT TRUNCATED)

Outbreak oof calicivirus gastroenteritis associated with eating frozen raspberries

Small round structured viruses (SRSVs - for example, calici-, astro-, and entero-viruses) are the commonest causes of outbreaks of non-bacterial gastroenteritis worldwide. Transmission of SRSVs by water and by various foods - including salads, bakery prod

Short sequences define genetic lineages: phylogenetic analysis of group A rotaviruses based on partial sequences of genome segments 4 and 9

Genetic diversity in strains of human group A rotaviruses was analysed by phylogenetic methods. The study material comprised 109 serotype G1 or G4 rotavirus samples isolated in Finland during 1986-1990. Parts of the coding regions of rotaviral genome segments 4 and 9, which encode proteins with serotype specificity, the spike protein VP4 (P serotype) and the outer capsid protein VP7 (G serotype), respectively, were sequenced. As determined by analysis of segment 4 sequences all G1 strains and all except one G4 strain showed P[8] specificity, the one being of P[6] specificity. The G1P[8] strains could be further differentiated into four groups based on segment 9 sequences, while G4P[8] strains formed only one group. Type P[8] (G1P[8] and G4P[8]) strains formed two main groups based on segment 4 sequences, suggesting free segregation of segment 4 between these G strains. Most global G1, G4 and P[8] strains in GenBank/EMBL originating from the 1970s to the present co-clustered with these groups, suggesting that the groups exist as relatively stable lineages. No linear accumulation of nucleotide substitutions was detected in strains of one serotype during the study period. Also, the deduced amino acids of the antigenic regions A, B and C of VP7 were nearly conserved within the phylogenetic lineages. Interestingly, only short amino acid sequences were necessary to divide the e-types correctly into phylogenetic lineages. These amino acid signature motifs were located in aa 29-68 of VP7 and aa 121-135 of VP4 of the G1 and P[8] lineages, respectively.

Waterborne outbreak of viral gastroenteritis

A waterborne epidemic took place in a Finnish municipality in April 1994. Some 1500-3000 people, i.e. 25-50% of the population, had symptomatic acute gastroenteritis. Laboratory findings confirmed adenovirus, a Norwalk-like agent, small round viruses (SRV), and group A and C rotaviruses as causative agents, Norwalk virus being the main cause of the outbreak. The epidemic was most probably associated with contaminated drinking water. The groundwater well, situated in the embankment of a river, was contaminated by polluted river water during the spring flood. A back flow from the river to the well had occurred via a forgotten drainage pipe.

Rotavirus serotypes and electropherotypes in Finland from 1986 to 1990

Four epidemic seasons of rotaviruses were studied in Helsinki during 1986-1990. This is the first Scandinavian study, where both electropherotypes and serotypes are determined. Out of 5316 fecal specimens 769 (14.5%) rotavirus positive samples were detected by electron microscopy. Of these, 645 isolates (83.9%) gave a clear RNA pattern in gel electrophoresis and they clustered into 87 electropherotypes. An illustrative number of isolates representing each electropherotype (= E-type) was serotyped using VP7 protein-specific monoclonal antibodies for serotypes G1-G4 and without exceptions, within one E-type only a single serotype specificity was found. After establishment of the serotype of each E-type, the distribution of serotypes was scored as 61.2%, 2.0%, 0.5% and 29.8% for G1-G4, respectively; 6.5% remained untypable. Two seasons had one predominant E-type (Season 1, 1986-87, and Season 3, 1988-89, 84.2% and 80.6% of rotavirus positive samples, respectively). Both were followed by a season with no predominant E-type, but several minor E-types. Altogether, 5 short E-types (13/645 samples) with serotype G2 specificity were found, most of them occurring in Season 2. Only 2 E-types (3 samples) belonged to serotype G3. Group C rotavirus was found in 8 specimens. In this study a shift in serotypes, from G1 to G4, was observed in Finland in 1988/89; a similar shift was reported in many European countries at that time.

Intracellular manipulation of disulfide bond formation in rotavirus proteins during assembly

Rotavirus undergoes a unique mode of assembly in the rough endoplasmic reticulum (RER) of infected cells. Luminal RER proteins undergo significant cotranslational and posttranslational modifications, including disulfide bond formation. Addition of a reducing agent (dithiothreitol [DTT]) to rotavirus-infected cells did not significantly inhibit translation or disrupt established disulfide bonds in rotavirus proteins but prevented the formation of new disulfide bonds and infectious viral progeny. In DTT-treated, rotavirus-infected cells, all vp4, vp6, and ns28 epitopes but no vp7 epitopes were detected by immunohistochemical staining with a panel of monoclonal antibodies. When oxidizing conditions were reestablished in DTT-treated cells, intramolecular disulfide bonds in vp7 were rapidly and correctly established with the restoration of antigenicity, although prolonged DTT treatment led to the accumulation of permanently misfolded vp7. Electron microscopy revealed that cytosolic assembly of single-shelled particles and budding into the ER was not affected by DTT treatment but that outer capsid assembly was blocked, leading to the accumulation of single-shelled and enveloped intermediate subviral particles in the RER lumen.

A family outbreak of gastroenteritis caused by group C rotavirus

A family outbreak of gastroenteritis caused by group C rotavirus is described. All five members of the family, with children between 8 and 15 years of age, fell ill with diarrhea. The diagnosis was initially based on the detection of rotavirus RNA showing a typical group C profile in gel electrophoresis in stool samples, and it was serologically verified from patient sera using a cell culture adapted porcine group C rotavirus as a source of standard antigen. All collected serum samples from the family contained IgM and/or IgG class antibodies to group C rotavirus measurable by immunofluorescence antibody test (IFAT). Group C rotavirus specific IgM class antibodies were present in the early serum samples in 3/4 patients. A roller tube neutralization test (NT) was established to demonstrate neutralizing antibodies to porcine group C rotavirus in human sera. These methods can be used to detect serologically group C rotavirus infections.