Candidate adenoviruses 40 and 41: fastidious adenoviruses from human infant stool

DNA restriction analysis of adenovirus prototypes 1 to 41

DNA restriction patterns of all known human adenovirus prototypes (1 to 41), ordered according to subgenera A to F, are presented for restriction endonucleases BamHI, BglII, BstEII, HindIII, and SmaI. This catalogue is a prerequisite for typing of adenoviruses by DNA restriction analysis in diagnostic laboratories and for strain identification in reference laboratories. To determine the genetic relationship of human adenoviruses within a subgenus and between subgenera, a pairwise analysis of comigrating fragments was performed. Adenoviruses of subgenus C were closely related. Adenoviruses of subgenus B showed two related clusters of four types each, whereas the numerous serotypes of subgenus D did not show any corresponding clustering. Little comigration was observed between DNA restriction fragments from members of subgenus A or F respectively.

Genome variation of 5 clinical adenovirus type 2 isolates determined by restriction enzyme digestion analysis. Brief report

The restriction enzymes Eco RI, Hind III and Pst I have been used to show that 5 adenovirus type 2 isolates can be divided into 2 genome types and within each type there are different genome variations.

Improved ELISA for the detection of adenovirus antigen in faeces extracts by the biotin/streptavidin interaction

Two enzyme-linked immunosorbent assays for detection of adenovirus antigen in faecal extracts have been established. A conjugate of rabbit anti-(human) adenovirus immunoglobulin and horseradish peroxidase (HRP) prepared by means of a hetero-bifunctional reagent, N-succinimidyl-3-(2-pyridyldithio) propionate (SPDP), was used in the conventional ELISA, and a biotin-labelled antibody in combination with a streptavidin/peroxidase complex in the other (BS-ELISA). A collection of 60 faecal extracts, in which adenovirus had been demonstrated by immunosorbent electron microscopy (ISEM) in 29 samples, was selected and examined by ELISA and BS-ELISA. The presence of adenovirus was demonstrated in 38 (63%) of the samples by BS-ELISA compared to 34 (58%) by ELISA, showing the advantage of the biotin/streptavidin system for setting up ELISA assays. Comparison of the three different techniques showed that the biotin/streptavidin (BS-ELISA) is the most sensitive assay for detection of adenovirus antigen in faecal samples.

Development and application of monoclonal antibodies for specific detection of human enteric adenoviruses

Monoclonal antibodies were prepared against enteric adenovirus by fusing P3-NS1/-Ag4-1 mouse myeloma cells with lymphocytes from BALB/c mice immunized with enteric adenovirus 40 (Ad40) G2297. Of the several putative clones secreting antibodies to adenovirus, five were found to react specifically to the enteric adenovirus. The specificity of two of these monoclones which recognize a single antigen of a molecular size of 17 kilodaltons was evaluated against 78 clinical isolates. One monoclone (5D8/2C2) reacted with both Ad40 and Ad41, and the other monoclone (2H6/C11) recognized Ad40 only in an enzyme-linked immunosorbent assay (ELISA). These ELISA results correlated well with those of the specific neutralization test or DNA restriction endonuclease analysis or both. The use of this rapid ELISA with these monoclones will find applications in the diagnosis of enteric adenovirus and should facilitate the epidemiologic studies of enteric adenovirus gastroenteritis.

Genome analysis of species 3 adenoviruses isolated during summer outbreaks of conjunctivitis and pharyngoconjunctival fever in the Glasgow and London areas in 1981

Genome analysis was performed on 125 adenovirus isolates from conjunctival swabs of patients with conjunctivitis obtained in Glasgow between 1981 and 1984. A summer outbreak in 1981 was mainly due to species 3 adenoviruses, of which genotype 3GB and five different genotypic variants cocirculated. Three species 3 variants were also observed in 1982. The genome changes of variants were located on physical maps of the Ad3 reference strain and found to be clustered near the ends of the adenovirus DNA (including the fiber area), whereas the hexon coding region was unaltered. In contrast to the genome heterogeneity observed among the species 3 adenoviruses collected in Glasgow in 1981 it was found that all 69 Ad3 isolates obtained from an outbreak of pharyngoconjunctival fever in a boarding school near London during the summer of 1981 possessed the 3GB genotype.

Studies on fastidious adenoviruses in Ontario: a distinct strain associated with gastroenteritis

From 100 cases of gastroenteritis among children caused by adenovirus infection in Ontario, 33 virus isolates were divided into three categories according to their biological behavior in tissue cultures. So far, the results of neutralization tests, structural protein analysis, and DNA restriction patterns showed that the virus of category 1 was similar to adenovirus type 40. However, the adenovirus of category 2 was a distinct adenovirus which shared some similarities with adenovirus type 5. Viruses of category 3 are still under investigation.

Characterization of rotaviruses and subgroup F adenoviruses from acute summer gastroenteritis in South Africa

Six hundred and sixteen specimens were collected from black children hospitalised with acute gastroenteritis during the summer and autumn of 1982-1983 (October to May). Eighty-five children (13.8%) shed rotavirus and at least 40 (6.5%) shed adenovirus (Ad) type 40 or 41 belonging to subgroup F. The highest monthly prevalence of shedding subgroup F adenoviruses (10.1%) coincided with a peak in admissions in midsummer, whereas the highest monthly prevalence of shedding rotaviruses (41.9%) coincided with a peak in admissions in autumn. There were at least five genome types of rotavirus, at least three genome types of Ad40, and at least five genome types of Ad41 circulating in the Johannesburg-Soweto area during the study period. The high rate of rotavirus shedding in autumn could not be attributed to an upsurge in infections by any particular rotavirus strain.

Laboratory procedures in adenoviruses. XII. Comparison of five ELISA methods for demonstration of hexon antigen

To demonstrate adenovirus hexon, four different arrangements of a four-layer ELISA, to be performed with commercially available reagents, were compared with a three-layer ELISA. After evaluation of specific and control reagents and their dilutions, the guinea pig/rabbit or the rabbit/chicken method were equally practicable and sensitive as the three-layer method with rabbit serum and superior to two other methods. By testing about 100 stool samples and 74 throat swabs containing adenoviruses, it turned out that the sensitivity (1 ng/ml hexon) appears satisfactory for stool specimens in adenovirus enteritis of infants, but is much less sensitive than isolation in cell culture for adenoviruses in throat swabs. As confirmatory test, specimen were incubated with an adenovirus rabbit antiserum or normal serum and then tested.

COMAP: a comigrating analysis program for estimating the relationship of adenoviruses on the genome level

The computer program COMAP is described that enables one to evaluate the relationship among adenovirus 6 strains by comigration analysis with regard to the genome. The required data were obtained by restriction analysis with several enzymes. The program is also important for identifying further adenovirus strains by DNA restriction analysis and to compare new restriction fragment patterns with stored data of known adenovirus strains. We believe that in this manner the DNA restriction analysis will become a valuable diagnostic procedure.

Enteric adenoviruses. Brief review

In 1978, the World Health Organisation initiated a programme for global prevention and control of childhood diarrhoeas. As a result, the relative importance of various pathogens in the aetiology of diarrhoea in many parts of the world has been recognised. Rotavirus, which ranks as the most prevalent viral pathogen in childhood diarrhoea may be closer to control as many vaccines are in sight. This has been made possible due to a decade of intense research since its discovery. E Ad, which probably ranks as the second most important viral pathogen has not received much attention. As has been discussed, much information has to be gathered about this virus, before W.H.O's. goal of controlling childhood diarrhoea is realised.

Specific detection and typing of adenovirus types 40 and 41 in stool specimens by dot-blot hybridization

A dot-blot hybridization test was developed which allowed the direct detection of fastidious enteric adenovirus DNA in stool specimens from children with diarrhea and simultaneous typing of the viruses as adenovirus type 40 (Ad40) or Ad41. Cloned PstI fragments of Ad40 and Ad41 were used as 32P-labeled probes in the test, which allowed detection of picogram quantities of viral DNA in 20 to 40 microliter of stool suspension. Results were obtained within 48 h. The type specificity of the test was evaluated with 76 specimens known to contain either Ad40 or Ad41 by restriction enzyme analysis. Sixty-one specimens had sufficient DNA to be detected without any removal of protein. Thirty-one adenoviruses were typed as Ad40, and 30 were typed as Ad41, giving 100% correlation with the results of restriction enzyme analysis. The other 15 specimens were detected and typed as Ad40 or Ad41 only after removal of protein by a phenol extraction method. The dot-blot hybridization method is particularly useful for identifying those Ad40 and Ad41 strains which defy all attempts at culture and will be a useful tool in the epidemiology of fastidious enteric adenovirus infections.

Cell transformation by the left terminal regions of the adenovirus 40 and 41 genomes

To study the transforming capacity of the two fastidious adenoviruses 40 and 41 (Ad40 and Ad41), we have cloned the left terminal regions of their genomes. Transfection with plasmids containing these regions leads to transformation of primary baby rat kidney (BRK) cells. Cell lines derived from transformed cells show an intermediate transformed phenotype. The left terminal region was present in at least 50 copies in cells transformed by Ad41 and in 2-3 copies in Ad40-transformed cells. The integration patterns of the plasmids containing the left terminal region of Ad41 were similar in three different cell lines.

Fecal adenoviruses from a longitudinal study of families in metropolitan Washington, D.C.: laboratory, clinical, and epidemiologic observations

During a 29-month period, we studied enteric infection in 70 families from a pediatric practice in suburban Washington, D.C. Fecal adenoviruses were detected in stools of 18 patients by tissue culture and electron microscopic procedures. From 6 through 11 months of age, the incidence of fecal adenoviruses associated with enteritis was seven per 100, and of confirmed enteric adenoviruses (EAds), three per 100 individuals per year. All EAds belonged to subgenus G (type 41). All three patients with EAds had diarrhea; two had vomiting and one had fever, but none required hospitalization. Ten of the 15 patients with non-EAds were younger than 2 years, and 60% had diarrhea, 40% had vomiting, and 20% had fever. Combined gastrointestinal and respiratory symptoms occurred more often in those who shed non-EAds (three of 11) than in matched controls (two of 48, P = 0.04). An adenovirus was detected in approximately 6% of gastroenteritis episodes, and confirmed EAds were present in approximately 2% of episodes of gastroenteritis in children younger than 2 years of age. None of the contacts of patients with non-EAds shed such virus in their stools. None of nine family contacts of those with EAd appeared to shed adenovirus in stool. In contrast, rotavirus spread readily to exposed adults (25% of 65) and children (56% of 62) when a child in similar families had rotavirus infection.

Specific labelling of human rotaviruses and adenoviruses with gold-IgG complexes

Human rotaviruses and adenoviruses were specifically labelled by an indirect immuno gold staining technique for electron microscopy. Rabbit antisera against human rota- and adenoviruses were used as the primary antibody and goat anti-rabbit IgG-gold complexes as secondary antibody. Optimal conditions for the procedure were established by testing serial dilutions of the antisera. Precoating of electron microscopy grids with bovine rotavirus antibody decreased nonspecific background staining and at the same time increased slightly the number of virus particles adsorbed to the grid. Noncultivable enteric adenoviruses showed no antigenic relationship to adenovirus type 2 and 6 from cell culture material when tested by this gold labelled antibody decoration technique. However, a slight cross-reaction was observed between adenovirus type 2 and type 6.

Enzyme-linked immunosorbent assay for detection of enteric adenovirus 41

An enzyme-linked immunosorbent assay (ELISA) for direct detection of enteric adenovirus 41 (Ad41) in stool specimens was developed and compared with an Ad40-specific ELISA described previously [Johansson et al, 1980]. Rabbit antiserum to Ad41 was obtained by immunization with purified virions. To eliminate genus-specific reactivity the serum was passed through an immunosorbent column containing soluble adenovirus components of members of subgenera A to E. The anti-Ad41 serum still displayed high reactivity against Ad40 and had to be immunoabsorbed with soluble virus components of Ad40 to be rendered type-specific. The absorbed antiserum was used in an indirect ELISA and proved to be specific for Ad41. No heterotypic reactivity against Ad40 or Ad1 through Ad35 was found. The Ad41-specific ELISA proved to be of equal sensitivity to electron microscopy. The type-specific ELISAs for Ad40 and Ad41 were evaluated by testing 76 stool specimens containing enteric adenoviruses originating from England and Scandinavia. All specimens could be typed--41 (54%) as Ad40 and 35 (46%) as Ad41. These results were confirmed by DNA restriction site analysis. The type-specific ELISA proved to be a specific, sensitive, and a rapid technique for detection of Ad41 and allowed clear-cut discrimination from Ad40 in clinical specimens.

Selection of nonfastidious adenovirus species in 293 cells inoculated with stool specimens containing adenovirus 40

Of 35 stool specimens isolated and examined in 293 cells, 15 isolates contained adenovirus species 40 (Ad40), and 4 of these 15 isolates also contained a nonfastidious adenovirus species (Ad1 in two cases, Ad18 or Ad31) which was selected over Ad40 during serial passage in the 293 cells. The selection of Ad1 over Ad40 was examined in detail. Restriction analysis of intracellular DNA and the relative infectivity titers of Ad40 and Ad1 at each passage level after the inoculation of 293 cells with a particular stool specimen demonstrated that although the amount of Ad40 DNA synthesized far exceeded that of Ad1, the relative infectivity titer of Ad40 was low. The growth characteristics of Ad40 were then compared with those of Ad1, Ad18, and Ad41 in singly infected 293 cell cultures. One-step growth curves showed the same growth rate in each case, with a latent period of 12 h and a maximum titer at 24 to 36 h postinfection. Yields of infectious Ad40 virus were consistently 100- to 1,000-fold lower than those of Ad1. This difference was reflected by a reduced yield of total AD40 virions (p1.34) as determined by 35S labeling experiments. However, the 3- to 10-fold reduction in total yield of Ad40 virions did not account for the 100- to 1,000-fold reduction in the yield of infectious virus.

Comparison of neutralization and DNA restriction enzyme methods for typing clinical isolates of human adenovirus

Sixty-five adenovirus isolates collected over a 3.5-year period were typed by both standard microneutralization techniques and restriction endonuclease digestion of viral DNA. Of the 65 isolates, 47 (72.3%) representing six adenovirus types could be typed by microneutralization. Eighteen isolates demonstrated partial neutralization with standard antisera to two or more adenovirus serotypes and thus could not be definitively typed. DNA analysis permitted typing of 64 of the 65 isolates (98.5%) (including four isolates which contained mixtures of two adenovirus types), and 12 different types were identified. Neutralization and DNA typing disagreed for five isolates, and in each case, digestion with multiple restriction endonucleases and DNA hybridization studies were consistent with the type assigned by DNA analysis. In addition, the DNA analysis method allowed the identification of genomic variants (genome types) of five adenovirus types. We conclude that typing clinical isolates of adenovirus by restriction endonuclease digestion of viral DNA can be done rapidly, provides additional epidemiological and typing information, and provides fewer ambiguous results than does typing by neutralization.

Examination of uncommon clinical isolates of human adenoviruses by restriction endonuclease analysis

Restriction endonuclease analysis was performed on reference strains of each unknown adenovirus subgenus, in comparison with 40 isolates not identified by our routine methods of neutralization with antisera of species 1 to 8. Several uncommon species would not have been identified initially without the assistance of reference laboratories (species 15, 35, and 37). Other species were identified by comparison with published adenovirus DNA restriction endonuclease patterns or from DNA analysis of reference strains (species 31, 40, and 41). Some isolates could not be matched beyond the level of presumptive adenovirus subgenus. Genomic DNA restriction endonuclease analysis of adenoviruses was useful for the identification of adenovirus isolates in a diagnostic virology laboratory. However, accurate interpretation of results will require more extensive DNA restriction endonuclease fragment analysis of a broader range of adenovirus species and genomic variant strains.

Specific properties of two enteric adenovirus 41 clones mapped within early region 1A

Enteric adenovirus type 40 (Ad40) and Ad41 form the sixth subgenus of human adenoviruses. They are associated with infantile diarrhea but cannot be isolated in conventional cell cultures. The genome of the fastidious enteric Ad41 has been cloned, and the cleavage sites of the genome produced by restriction endonucleases BamHI, EcoRI, HpaI, NruI, PvuI, and SalI have been mapped. To develop useful hybridization methods for direct detection of adenoviruses, a restriction fragment library containing Ad41 DNA, with plasmid pBR322 as vector, has been constructed. Clones have been isolated which contain 8 of 10 possible BamHI fragments of Ad41, inserted into the BamHI cleavage site of the vector. Two of these clones are particularly useful for the detection of adenoviruses. One clone detects members of all human adenovirus subgenera, and the second clone is specific for enteric adenoviruses, in particular Ad41. A conspicuous absence of detectable homology was noted at 1.5 to 3.3 map units of the Ad41 genome in hybridizations against other serotypes of adenoviruses, including the closely related enteric Ad40. This sequence corresponds to the 5' portion of early region Ia.

Molecular epidemiology of adenoviruses: global distribution of adenovirus 7 genome types

Adenovirus 7 (Ad7) is the adenovirus species that most frequently has been associated with severe illness. Seven distinct genome types of adenovirus 7, Ad7p, Ad7a, Ad7b, Ad7c, Ad7d, Ad7e, and Ad7f, can be identified by using restriction endonucleases BamHI and SmaI. We analyzed the distribution of the different Ad7 genome types among 314 isolates from patients and healthy shedders. The Ad7b and Ad7c genome types accounted for 90% of the isolates from patients and appeared to be mutually exclusive. A shift from Ad7c to Ad7b genome types occurred in 1969 in Europe and in 1975 in Australia. During the last decade, Ad7b genome types predominated in Australia, Europe, and North America. Ad7c was detected in South Africa, Ad7d was detected in China, Ad7e was detected in Brazil, and Ad7f was detected in Australia. The Ad7p and Ad7a genome types dominated among isolates obtained from healthy shedders and appeared scattered through the years and the geographical areas. The prevalence of Ad7 infections is high in Japan as judged by the herd immunity. However, the low percentage (2%) of Ad7 isolates among all adenovirus isolates chiefly from patients, coupled with 30 to 50% antibody prevalence, argues for a high proportion of inapparent infections and, hence, Ad7 strain(s) of low pathogenicity.

Physicochemical properties of the DNAs of the fastidious adenovirus species 40 and 41

The DNAs of the two fastidious adenovirus species 40 and 41 (Ad40 and Ad41) have been studied by restriction endonuclease cleavage, CsCl density gradient centrifugation, and liquid-phase hybridization. For Ad40 DNA, cleavage maps were constructed for the restriction endonucleases EcoRI, SalI, ClaI, BstEII, BclII, and PvuI. The EcoRI, SalI, ClaI, and XhoI maps could be established for Ad41 DNA. The buoyant density in CsCl of DNAs of the fastidious species is 1.711 g/cm3 corresponding to a G + C content of 52%. The homology of the DNAs from Ad40 and Ad41 proved to be 62-69%. These results are consistent with previous reports on antigenic and DNA restriction enzyme analysis in which the classification into two species was proposed (J. C. De Jong, R. Wigand, A. H. Kidd, G. Wadell, J. G. Kapsenberg, C. J. Muzerie, A. G. Wermenbol, and R.-G. Fritzlaff, J. Med. Virol. 11, 215-231 (1983), and I. Uhnoo, G. Wadell, L. Svensson, and M. Johansson, Dev. Biol. Stand. 53, 311-318 (1983].

A simple and rapid method for typing adenoviruses 40 and 41 without cultivation

Fastidious adenovirus DNA in faecal samples obtained from children with acute gastroenteritis was extracted by a simple and rapid method. The extracted viral DNA was characterized by restriction endonuclease SmaI treatment. Fastidious adenovirus DNA was detected in 58 of 65 cases. If faecal samples were too small it was not always possible to identify virus DNA.

Rapid presumptive recognition of diarrhea-associated adenoviruses

The quantity of adenoviruses in a diarrhea stool provided a strong presumptive indication of the presence or absence of an adenovirus from subgenus F or G (proposed species 40 or 41). These adenoviruses were found in the stools of 91% of 56 acutely ill diarrhea patients with one or more than one adenovirus particle per min of direct electron microscopic viewing, as compared with 40% of 20 acutely ill diarrhea patients with less than one detected adenovirus particle per min of viewing.

Silver staining of DNA restriction fragments for the rapid identification of adenovirus isolates: application during nosocomial outbreaks

The ultrasensitive photochemical silver stain for nucleic acids, described by Beidler et al. (1982), has been applied to the detection of adenovirus restriction fragments as a relatively rapid technique for the identification of virus isolates. In this study, restriction enzyme cleavage analysis was used to characterize adenovirus isolates from what appeared to be two nosocomial outbreaks. The first outbreak was thus shown to include two clusters of patients, and involved two serotypes Ad7c and Ad40. The second outbreak was unrelated and involved Ad35. Although restriction analysis does not replace serum neutralization as a routine method for typing adenoviruses, it is a much more rapid means of discriminating between different patient isolates, providing a current rather than retrospective analysis of a nosocomial outbreak. During the first outbreak, restriction analysis identified two distinct adenovirus serotypes from one patient--Ad7c from a nasopharyngeal aspirate and Ad41 from a stool specimen. Restriction analysis is also valuable for the sub-typing of virus isolates. In this study, the Ad40 and Ad41 isolates were shown to be variants of the respective prototype strains.

Importance of enteric adenoviruses 40 and 41 in acute gastroenteritis in infants and young children

In a prospective 1-year study of acute infantile gastroenteritis, adenoviruses were detected in the stools or by seroconversions, or both, in 56 of 416 (13.5%) ill children. By use of DNA restriction enzyme analysis, enzyme immunoassay, and culture techniques, 33 of 56 (59%) adenovirus specimens were identified as enteric adenoviruses 40 and 41 (Ad40 and Ad41). They were found as the sole recognizable cause of diarrhea in 30 of 416 (7.2%) ill children and in 0 of 200 controls. Three additional ill children had enteric adenoviruses as a part of a dual infection. Evidence for established adenoviruses (Ad1 through Ad39) in gastroenteritis was found in 15 of 416 (3.6%) ill children but also in 3 of 200 (1.5%) controls. Eight adenovirus specimens remained untyped. Seroconversions were demonstrated in 17 of 18 (94%) paired serum samples from patients shedding enteric adenoviruses. The predominant symptom of infections with enteric adenoviruses was diarrhea, with a mean duration of 8.6 days (Ad40) and 12.2 days (Ad41). One-third of the children with Ad41 infections had prolonged symptoms (greater than or equal to 14 days). The frequency of respiratory symptoms was low (21%). The established adenoviruses presented a different clinical picture, characterized by diarrhea of shorter duration, higher fever, and significantly increased occurrence of respiratory symptoms (79%). In conclusion, enteric adenoviruses appear to be an important cause of acute infantile gastroenteritis, second only to rotaviruses in this study.

Diagnosis of fastidious enteric adenoviruses 40 and 41 in stool specimens

Thirty-five stool specimens, collected over a 14-week period from pediatric gastroenteritis patients and shown to contain adenovirus by electron microscopy, were inoculated onto 293 and HeLa cells. Virus isolates were characterized by serum neutralization and restriction endonuclease cleavage analysis of viral DNA from infected cells. Adenovirus was isolated upon primary inoculation of 293 cells from all 35 specimens shown to contain adenovirus by electron microscopy. Fastidious adenoviruses 40 and 41 (Ad40 and Ad41) were found in 17 (49%) of the stool specimens, and 4 of these specimens contained a conventional species (Ad1, Ad1, Ad18, Ad31) as well as Ad40. This was first manifest by the observation that four of the isolates which initially grew only in 293 cells acquired the capacity to grow in HeLa cells upon subsequent passage. In each case, the conventional species was undetectable by DNA analysis in the original inoculum but was selected in 293 cells and became the only one detectable by the second passage. Four other specimens, containing Ad1 or Ad31 alone, failed to grow initially in HeLa cells but did grow in 293 cells. The results of this study demonstrate therefore that (i) 293 cells are more sensitive than HeLa cells for the isolation of conventional as well as fastidious enteric adenovirus species and (ii) identification of viruses from patient specimens should involve minimal passage of the virus in cell culture, as a single passage can result in misdiagnosis of the virus associated with the infection.

Studies of stools from pseudomembranous colitis, rotaviral, and other diarrheal syndromes by frequency-pulsed electron capture gas-liquid chromatography

Thirty-five patients with various diarrheal syndromes and 22 controls were studied. All stool samples were carefully cultured for Clostridium difficile, using selective isolation media. Cytotoxin assays with proper antitoxin neutralization were done in MRC-5 cells. The stool samples were extracted four times, three times at pH 2 and once at pH 10, using CHCl3 or ether. Derivatizations of extracts were done with trichloroethanol, heptafluorobutyric anhydride, and heptafluorobutyric anhydride-ethanol, and all derivatives were analyzed by frequency-pulsed electron capture gas-liquid chromatography (FPEC-GLC). A dedicated computer was used to assist in both qualitative and quantitative data analysis. Isocaproic acid (iC6) was always found in stool from which C. difficile was isolated and was absent in C. difficile-negative specimens. p-Cresol was found frequently in both persons with pseudomembranous colitis and controls. Tryptamine was found in stool containing C. bifermentans. The FPEC-GLC profiles of persons with acute diarrhea were very different from those of normal persons. Diarrhea associated with adenovirus and rotavirus, Klebsiella spp., and Escherichia spp. showed different FPEC-GLC patterns. Stools from well persons consistently contained full-scale peaks of pyruvic, acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids. In rotavirus stools isobutyric, isovaleric, and valeric acids were reduced in quantity from those found in control stools, whereas propionic and butyric acids were increased.

EM study of fastidious adenovirus type 40 replication in vitro

Primary human embryo kidney cells and Chang conjunctival cells were inoculated with fastidious enteric adenovirus type 40. Mature virions were seen in the nuclei of infected Chang cells, but not in human embryo kidney cells, indicating that at least a proportion of Chang cells can support the entire replicative cycle.

Pathogens detected in the faeces of children with diarrhoea in a Sydney hospital

During a 54-week period, faecal samples taken from 350 children under 5 years of age, who were admitted with acute diarrhoea to the infectious diseases ward of a Sydney hospital, were examined for pathogens. Rotavirus was detected as the sole agent in the specimens of 58 patients (16.6%), enteroviruses in those of 26 patients (7.4%), salmonellae in those of 19 patients (5.4%) and Campylobacter jejuni in those of 15 patients (4.3%). Shigellae were not detected. The results are discussed and, in view of the changing patterns of infection, it is suggested that there is a continuing need for research into the causes of enteritis in Australia.

Cloning and physical mapping of enteric adenoviruses (candidate types 40 and 41)

We have studied the DNAs of fastidious enteric adenoviruses recovered from the stools of infants with gastroenteritis. By endonuclease analysis, the strains examined represent candidate adenovirus types 40 and 41, which are thought to comprise new adenovirus subgroups F and G. Cloning of DNA from representative enteric adenovirus isolates, together with hybridization and subcleavage analysis, permitted the mapping of restriction enzyme cleavage sites. Although the restriction profiles are different for the two strains, they appear to have several cleavage sites in common. Cross hybridization studies show considerable homology between the subgroup F and G strains but much less homology to adenovirus 2. In addition, regions on both ends of enteric adenovirus genomes (map units, 2.9 to 11.3 and 75 to 100) possess little or no homology to adenovirus 2. Restriction enzyme digests reveal submolar fragments that map to the terminal regions of the genome. Electron micrographic studies of denatured and renatured DNA strands suggest that the submolar fragments may derive from cleavage of defective molecules. Inverted terminal repeat sequences were shown to comprise 0 to 3.2% of the length of complete (greater than or equal to 22 megadaltons) enteric adenovirus DNA molecules but 4 to 69% of incomplete-length (less than 22-megadalton) molecules.

Genome variants of adenovirus 41 (subgroup G) from children with diarrhoea in South Africa

Fifteen strains of faecal adenovirus from 3 continents (4 from Europe, 4 from Canada, and 7 from South Africa) were typed as Ad41a by restriction enzyme analysis o the DNA using Sma I. The DNA of the strains was further compared by digestion with 9 other restriction enzymes. All strains had the same cleavage sites for enzymes Bam HI, Bg1 I, Sst I, Pvu II, and Xho I, indicating a close relationship. The Canadian and European strains also had the same cleavage sites for Hind III, Eco RI, Bst EII, and Kpn I, within the limits of resolution of the technique. Only one of the 7 South African strains had a combination of restriction sites identical to the European and Canadian strains, whereas Hind III, Eco RI, Bst EII, and Kpn I digests of the other 6 South African Ad41 DNAs showed the existence of 4 other genome types of Ad41. All 15 Ad41a strains studied were easily distinguished from Ad40 strains using any of the 10 restriction enzymes.

Genome variants of human adenovirus 40 (subgroup F)

Twenty-six strains of faecal adenovirus from three continents (two from Europe, 16 from South Africa, and eight from Canada) were typed as Ad40 by restriction enzyme analysis of the DNA using Sma I. The DNA of the strains was further compared by digestion with six other enzymes, namely Bam HI, Eco RI, Bgl I, Xho I, Sst I, and Hind III. At least two different restriction profiles were found to exist for each enzyme. Nineteen of the 26 strains studied had the same combination of profiles for all the enzymes, within the limits of resolution of the technique. This genome type was detected from all three continents and included the Finnish reference strain Hovi-X. The other seven strains were genome variants, representing five other genome types. Three genome types were detected only in South African specimens, whereas one genome type was detected in single specimens from both South Africa and Canada. Strain Dugan from Holland, indistinguishable from other Ad40 strains in neutralization tests using polyclonal antibody preparations [de Jong et al, 1983], deviated from the common Hovi-X-like genome on digestion of the DNA with any of the enzymes except Sma I.

Characteristics of mastadenovirus h 8, the causative agent of epidemic keratoconjunctivitis

Adenovirus 8 (Ad 8, strain 1127) has the general structural features of an adenovirus; it produces the genus-specific hexon antigen. The fiber length of 12 nm corresponds to that of other subgenus D adenoviruses. In hemagglutination-inhibition, Ad 8 is related to Ad9 and Ad 15/H9. The slow multiplication, compared to most other subgenus D viruses, was shown not to be caused by an extended growth cycle, but appears to be due to an inefficient virus release into the medium. After restriction analysis with the enzymes Sma I and Bgl II, the typical fragment patterns of species from subgenus D were obtained, while very different patterns emerged from the analysis with Hind III, Bam HI, and Bst E II endonucleases. Several strains of Ad 8 produced more penton-associated toxin than Ad 15/H9 used as reference virus from subgenus D, which could explain the "clumping CPE" caused by Ad 8. Ad 8 toxin was neutralized by antisera from many adenovirus species. The poor virus yield of Ad 8 was not improved by removing soluble viral or cellular substances; all other attempts to improve virus yield by varying the conditions of cell culture also failed.

The influence of iododeoxyuridine pretreatment of various cell cultures on adenovirus multiplication

Treatment of cell cultures with iododeoxyuridine (IUdR) before virus inoculation may enhance the subsequent virus multiplication. This effect was studied in seven kinds of cell cultures with seven human adenoviruses from six subgenera. IUdR (50 micrograms/ml) was added 24 h after the seeding of cells, left for 2 days, and removed before virus inoculation. IUdR had no effect on cell proliferation. Viral cytopathic effect was enhanced in many instances by IUdR pretreatment. However, virus multiplication was enhanced weakly in only four cases [adenovirus 7 in Vero, African green monkey kidney, cynomolgus monkey kidney; adenovirus 4 (Ad4) in HeLa cells], and strongly only for Ad4 in Vero cells, which are semipermissive for Ad4. IUdR pretreatment of Vero cells shortened the replication cycle for Ad4 and increased sensitivity for minimal virus concentrations about 1000-fold. From immunofluorescence experiments it appears that more than one infectious particle is required to infect an untreated Vero cell.

Antibodies to fastidious faecal adenoviruses (species 40 and 41) in sera from children

Three hundred and seventy-seven single sera from children in the United Kingdom, Hong Kong, New Zealand, Gambia, Guatemala, and Kuwait were tested for antibodies to fastidious fecal adenoviruses (species 40 and 41) by neutralisation test using a variant of Ad41 (Ad41a). All children were less than 12 years of age, and at least 41.1% of the total tested had antibodies. One hundred and fifty-four of these sera were collected during the 1960s from London children attending day nurseries, and 54.5% had antibodies to Ad40 or Ad41. The proportion of seropositive children from an isolated Gambian village community in 1979 was similar to the proportion of seropositives in London children bled in 1979-1980.

Isolation and identification of enteric adenoviruses

Thirty-four out of 64 faecal samples with adenovirus particles, as seen by electron microscopy, were found to contain adenovirus 40 or 41 by direct isolation and neutralization in Chang's conjunctival cells, mostly within one week. (Ad40 and 41 candidate viruses are serologically related.) 6 other adenovirus species were isolated; 6 samples gave equivocal results, and 18 were negative. A genus-specific ELISA with an antihexon coat yielded positive results in 40 out of 55 samples; the test failed to identify adenovirus antigen in 10 out of 17 specimens, which were found negative by culture. All of them were negative by immunfluorescence of inoculated Chang cell cultures. Hence the failures are probably due to insufficient amount of virus in the samples. The predominance of only two adenovirus species associated with gastroenteritis in children and the ease of cultivating and identifying them should help to elucidate their etiological significance.