A new chemolithoautotrophic arsenite-oxidizing bacterium isolated from a gold mine: phylogenetic, physiological, and preliminary biochemical studies.

A previously unknown chemolithoautotrophic arsenite-oxidizing bacterium has been isolated from a gold mine in the Northern Territory of Australia. The organism, designated NT-26, was found to be a gram-negative motile rod with two subterminal flagella. In a minimal medium containing only arsenite as the electron donor (5 mM), oxygen as the electron acceptor, and carbon dioxide-bicarbonate as the carbon source, the doubling time for chemolithoautotrophic growth was 7.6 h. Arsenite oxidation was found to be catalyzed by a periplasmic arsenite oxidase (optimum pH, 5.5). Based upon 16S rDNA phylogenetic sequence analysis, NT-26 belongs to the Agrobacterium/Rhizobium branch of the alpha-Proteobacteria and may represent a new species. This recently discovered organism is the most rapidly growing chemolithoautotrophic arsenite oxidizer known.

Prevalence and genomic variation of Norwalk-like viruses in central Australia in 1995-1997.

Norwalk-like viruses (NLVs) have now been found to be important causes of gastroenteritis amongst infants and young children as well as older children and adults. Although detected, such viruses appeared not to be a major cause amongst infants and young children hospitalized with gastroenteritis in Alice Springs, central Australia over the period January 1995-December 1997. Nine NLV-positive cases were identified amongst stools from 360 different patients. From the nine cases however, eight different NLV strains were identified from comparisons of the sequence of a section of the RNA polymerase gene, and a high degree of genomic diversity was evident amongst them. In general, these strains were more similar to those identified in other countries than to those identified in central Australia over the three year period. Of the strains identified, six (and most probably seven) were classified in genogroup I, while only one was classified in genogroup II. This predominance of genogroup I strains is in contrast to most of the more recent findings made elsewhere, including those made in other parts of Australia. Phylogenetic analysis indicated that the central Australian strains spanned a range of known representative NLV strains, with one of the genogroup I strains showing a 96% nucleotide identity to Saratoga virus.

Effect of human milk prostaglandins and lactoferrin on respiratory syncytial virus and rotavirus.

The effect of lactoferrin and prostaglandins E and F2 alpha on the growth of rotavirus and respiratory syncytial virus in cell culture was investigated. Lactoferrin inhibited the growth of respiratory syncytial virus at a concentration tenfold lower than that normally present in human milk. The prostaglandins had no effect on either virus growth, even at a concentration of 100-fold more than that found in human milk. Lactoferrin may have some antiviral properties in human milk in addition to its known antibacterial functions.

Sequence conservation and expression of the gene encoding the outer capsid glycoprotein among human group C rotaviruses of global distribution.

Group C rotaviruses have been identified recently from fecal samples of children with diarrhea in the United States. Using reverse transcriptasepolymerase chain reaction and sequence analysis, we sequenced gene 8s encoding VP7 from two U.S. strains (RI-1 and RI-2), and eight other strains isolated from patients on four continents, and compared these with the sequences of four published strains. The gene 8s of the 14 strains were remarkably conserved in size and in predicted primary and secondary structures. When the sequences of the human VP7s were compared with that of the prototype porcine Cowden strain, six regions were found variable in both deduced primary and predicted secondary structures, four of which were predicted to be hydrophilic and might determine serotype specificity. Gene 8 of the human S-1 strain was further characterized by expression in recombinant baculoviruses. The expressed product was immunogenic but failed to elicit neutralizing antibodies. Our sequence analysis indicates that all the human strains characterized to date belong to a single G genotype, which may constitute a single G serotype, pending further antigenic analysis. Whether the human strains and the Cowden strain are the same serotype remains to be determined.

Serum antibodies to human enteric coronavirus-like particles in Australia, South Africa, Indonesia, Niue, and Papua New Guinea.

Relatively high levels of antibody to human enteric coronavirus-like particles were detected in the sera from rural Aborigines in Australia. Levels were generally much lower in the sera from urban Aborigines, and extremely low to not detectable in the sera from Europeans. Antibody to coronavirus-like particles was also detected in the sera from rural blacks from South Africa, in the sera from Indonesia and Niue, and also possibly in the sera from rural villagers from Papua New Guinea, but in the latter case at only very low level.

Neutralization kinetic analysis showed that strains of echovirus types 7, 11 and 17, unlike those of echovirus type 30, varied antigenically over time in Melbourne, Australia.

Using neutralization kinetic analysis, isolates of echovirus types 7, 11 and 17 were found to generally vary antigenically over periods of 22, 20 and 10 years respectively in Melbourne, Australia. This is in contrast to a previous finding of antigenic constancy amongst echovirus type 30 isolates in Melbourne over a 23 year period.

Characteristics of Australian human enteric coronavirus-like particles: comparison with human respiratory coronavirus 229E and duodenal brush border vesicles.

The polypeptide profiles of highly purified coronavirus-like particles (CVLPs) proved to be very different from that of human respiratory coronavirus 229E and showed the particles not to be coronaviruses. Differences in polypeptide profiles and morphology between the CVLPs and duodenal brush border vesicles suggested that the CVLPs were also not such vesicles. Although they shared some basic overall similarity, the polypeptide profiles of three different but possibly antigenically identical CVLP preparations from Central Australian Aborigines were very dissimilar in detail. At least 38, 39 and 48 bands respectively were observed on the three profiles. At least 46 bands were visible on the polypeptide profile of CVLPs from a Vietnamese immigrant to Australia, and it also differed in detail from those of the Central Australian CVLPs. Indications of antigenic difference were obtained between Central Australian CVLPs and CVLPs from India, Kiribati, South Africa and Vietnamese immigrants to Australia. Antigenic difference was also suggested between the Central Australian CVLPs and those from one distant location within Australia, but antigenic similarity with those from another was indicated.

Antibody prevalence to human enteric coronavirus-like particles and indications of antigenic differences between particles from different areas. Brief report.

Antibody to human enteric coronavirus-like particles was detected in Australian Aborigines, but at lower levels or not at all in Europeans. There were indications of antigenic differences between particles from different areas. Support was provided for consideration of such particles as infectious agents.

Characteristics of an SA 11 rotavirus variant differing in the outer capsid glycoprotein.

The ease with which variants of rotaviruses arise has been further illustrated by the isolation of a variant of simian rotavirus SA 11 differing in the major outer capsid glycoprotein VP7. The difference in mol.wt. between VP7 of the variant (STA virus) and SA 11 virus was 3 X 10(3), with this polypeptide of STA virus still retaining the mannose-rich carbohydrate moiety. Limited proteolytic analysis using Staphylococcus aureus V.8 protease and trypsin also showed a difference in structure between the VP7 of the two viruses. SA 11 and STA viruses differed antigenically, although they could not be considered to be different serotypes. In other properties, such as rate of growth, the two viruses appeared to be very similar. The evidence overall pointed to STA virus being a variant strain rather than a reassortant, but the appearance of such variants may prove to have important implications in rotavirus immunoprophylaxis.

Neutralization kinetic analysis of echovirus 30 and coxsackievirus B4 strains revealed little antigenic variation amongst the echovirus strains.

An antigenic analysis was made of echovirus 30 and coxsackievirus B4 isolates by determining neutralization rate constants in neutralization kinetic tests. The seven echovirus 30 isolates included the prototype strain and six others isolated in Melbourne, Australia, between 1959 and 1982. Little antigenic heterogeneity was observed in contrast to the evidence of antigenic variation recorded in similar tests on seven coxsackievirus B4 isolates. These isolates also included the prototype strain, as well as six others isolated in Melbourne between 1958 and 1973. The results obtained with the coxsackievirus B4 isolates were in keeping with those observed particularly with the polioviruses and also coxsackievirus B4 by other workers. Those obtained with the echovirus 30 isolates were unexpected, as this virus is also a member of the enterovirus group.

Variation in human rotavirus electropherotypes occurring between rotavirus gastroenteritis epidemics in central Australia.

The changes in human rotavirus electropherotypes, occurring during a period including two rotavirus gastroenteritis epidemics in 1976 and 1979 in relatively remote Central Australia, were determined by polyacrylamide gel electrophoretic analysis of the rotavirus genome ribonucleic acid. A number of different electropherotypes were present during each of the epidemics, although a single type was predominant in each one. The predominant electropherotype of the first epidemic persisted in the area for approximately 2 years afterwards. Apart from this electropherotype, only three others were recognized in the 3 years between the two epidemics. One of these, first seen 1 year before the second epidemic, bore a very close similarity to the predominant type of the second epidemic. Altogether, 12 different electropherotypes were recognized during the period of the survey. No type common to both areas was found when rotavirus electropherotypes recognized in Central Australia were compared with those detected in a 1973-to-1979 survey in Melbourne, Australia.

Inactivation of a rotavirus by disinfectants.

Rotavirus SA 11, clarified and in human faeces, was exposed to eight commonly used hospital and laboratory disinfectants for periods between 15 seconds and two hours. Of the three hard disinfectants tested, 0.95 by volume (95% v/v) ethanol and 0.05 by volume (5% v/v) Biogram were more effective in inactivating SA 11 than 4% (w/v) or 10% (w/v) formaldehyde, with 0.95 by volume ethanol being the most effective of all of the disinfectants tested. None of the skin disinfectants tested, Betadine, Hexol, Hibiclens and Hibitane in alcohol, were very effective against the rotavirus in the presence of faeces, although Hexol and Hibitane in alcohol inactivated clarified SA 11 fairly quickly. Because of its rapidity of action against SA 11, even in the presence of faeces, and relatively non-deleterious effect on the skin, 0.95 by volume ethanol may be more useful as a handwash than these skin preparations. Undiluted Milton Antibacterial Solution gave very variable results, while the same solution diluted 1 in 80 had little effect on clarified SA 11.

Rotavirus and coronavirus-like particles in aboriginal and non-aboriginal neonates in Kalgoorlie and Alice Springs.

In a series of six-month surveys carried out in Kalgoorlie and Alice Springs Hospitals, rotavirus was infrequently detected both in Aboriginal and in non-Aboriginal neonates. Coronavirus-like particles were also detected infrequently, but they were found more often in Aboriginal than in non-Aboriginal neonates. The surveys did not detect any 28-nm virus-like particles.

Comparison of an enzyme-linked immunosorbent assay for quantitation of rotavirus antibodies with complement fixation in an epidemiological survey.

The development of a micro-scale enzyme-linked immunosorbent assay (ELISA) with horseradish peroxidase as the marker enzyme for the detection and measurement of human rotavirus antibodies is described. A semipurified preparation of the serologically related simian agent, SA-11 virus, was used as the antigen. Test sera were reacted with antigen-sensitized wells in disposable poly-vinyl microplates. Any attached antibody was detected by the addition of peroxidase-labeled anti-species immunoglobulin (conjugate) followed by assay of the enzyme reaction with its substrate, hydrogen peroxide plus 5-aminosalicylic acid. This micro-ELISA was compared with complement fixation in a seroepidemiological study of the age prevalence of rotavirus antibody in Aboriginal and European populations living in the same outback area in Australia. The ELISA (results read with the naked eye) proved to be approximately 16 times more sensitive than complement fixation. Of Aborigines, 71% had rotavirus complement-fixing antibody, as compared to 45% of Europeans. By ELISA 100% of both populations had rotavirus antibodies. Mean antibody titers in the different age groups were higher in Aborigines than in Europeans. Antibody levels rose steeply throughout the first 20 years of life, remained high during the next 20 years, then increased again at least up to the age of 60 years. The micro-ELISA was practical, simple to perform, and more suitable than complement fixation for large seroepidemiological rotavirus studies. It also has potential for serodiagnosis of the disease, both in the laboratory and in the field.

Coronavirus-like particles in Aboriginals and non-Aboriginals in Western Australia.

Pleomorphic virus-like particles which resemble coronaviruses in morphology were found in faecal specimens from Aboriginal and non-Aboriginal children in Western Australia. They were equally prevalent in those with or without symptoms of diarrhoea. A much greater proportion of Aboriginal than non-Aboriginal children were found to be excreting the particles. The proportion of children who excreted the virus-like particles increased with age. Coronavirus-like particles, indistinguishable from those found in humans, were found in a number of Aboriginals' dogs.

A survey of rotavirus associated with gastroenteritis in Aboriginal children in Western Australia.

In a year-long survey which was carried out between April, 1975, and March, 1976, faecal specimens from Aboriginal and some non-Aboriginal children who suffered from gastroenteritis were examined by electron microscopy for rotavirus, and also tested for bacteria and parasites. The children were under six years of age and came from all parts of Western Australia, except Perth. Rotaviruses, "astroviruses" and adenoviruses were detected as well as the usual potentially pathogenic bacteria and parasites. Two peaks of rotavirus incidence were found during the year in specimens from Kalgoorlie, but only one peak occurred in Derby. Rotavirus was somewhat more frequently seen in non-Aboriginal than Aboriginal children.