Isolation of reovirus type 2 from diarrheal feces of pigs.

Reoviruses designated as OS-320 to OS-324 were isolated from a total of 5 fecal specimens from 3 with diarrhea and 2 apparently healthy pigs aged 3 months. The serotype of these isolates was determined as reovirus type 2 by cross neutralizing tests. Furthermore, the results of hemagglutination test suggested the isolates were different from the other reoviruses. A survey of neutralizing antibody against reoviruses showed type 2 virus was widely prevalent among pigs in Okayama Prefecture. This paper is the first report of the isolation of reovirus type 2 from pigs.

Latex agglutination test for canine parvovirus.

Canine parvovirus (CPV) was detected in faeces from dogs with diarrhoea by a specific slide agglutination test using latex particles coated with anti-CPV monoclonal antibody (LA-anti-CPV). The agglutination of LA-anti-CPV with CPV on a glass slide was evident macroscopically within 2 min. The sensitivity of the latex agglutination (LA) test was similar to that of the hemagglutination test. The LA test is available for the rapid diagnosis of CPV infection at an animal hospital.

Isolation of group B porcine rotavirus in cell culture.

While group A and C rotaviruses have been grown in cell culture, group B rotavirus has never been cultured. In this study we successfully isolated porcine group B rotavirus in swine kidney cells. Pancreatin treatment is essential for the propagation of group B rotavirus.

Isolation of a serotype G6P11 bovine rotavirus showing two-way cross-neutralization with the serotype G10P11 virus.

Four stains designated as OB94-1 to OB94-4 of group A bovine rotavirus (BRV) were isolated from 35 fecal samples of calves with diarrhea in sporadic outbreaks. In VP7 (G) and VP4 (P) serotyping of these isolates, OB94-1 to OB94-3 were determined as G6P5, G6P5 and G10P5, respectively, by cross neutralization (NT) test and the G- and P- serotyping polymerase chain reaction (PCR) analysis. OB94-4 showed a one-way antigenic relation with the Lincoln stain (G6P1) and a weak antigenic relationship with the KK3 strain (G10P11), and was determined as G6P11 by the PCR method. Thus, OB94-4 was shown to be a new G6 BRV with different antigenic properties from the others in the NT test.

Drug resistance and conjugative R plasmids in Escherichia coli strains isolated from migratory waterfowl.

We evaluated drug resistance and R plasmids of 554 stains of Escherichia coli isolated from feces of migratory watefowl, including whistling swans (Cygnus columbianus), pintails (Anas acuta) and black-tailed gulls (Larus crassirostris) collected from the San-in District, Japan, between each November and March, 1983 to 1984, 1984 to 1985, and 1985 to 1986. Seven antimicrobial agents were tested: dihydrostreptomycin (DSM), kanamycin, spectinomycin, ampicillin (ABPC), oxytetracycline (OTC), chloramphenicol, and sulfadimethoxine (SDMX). Many strains were resistant to several drugs; in particular, all strains were resistant to SDMX. Both multiple drug resistant strains and drug resistance patterns occurred most frequently in strains isolated from whistling swans, followed by black-tailed gulls, and pintails, respectively. Of 233 strains, 128 (55%) carried transmissible R plasmids. The drugs with the largest number of resistance patterns observed were, in descending order, OTC, DSM, ABPC, and SDXM.

Yersinia pseudotuberculosis in China.

Thirty strains of Yersinia pseudotuberculosis were isolated from rabbits (17 strains), wild rats (9 strains) and house rats (4 strains) in China between 1990 and 1993. The biochemical properties of these isolates were identical with those of Y. pseudotuberculosis and no special characteristics were found in these strains. Serologically, serogroups 4b and 5b were identical to isolates found in Japan, and a new serogroup 1c and unclassified strains have also been detected. The existence of virulence-associated properties were different among strains. The pYV plasmid was detected from 6 strains of 30 isolates. This report documents the presence of Y. pseudotuberculosis in China, providing important epidemiological information.

Experimental infection with avian infectious bronchitis virus (Kagoshima-34 strain) in chicks at different ages.

Chicks at 2, 4 or 6 weeks of age were experimentally infected individually with a nephrosis/nephritis-causing avian infectious bronchitis virus (IBV) strain Kagoshima-34. The susceptibility of chicks in each group to the infection was compared, based on the clinical signs, excretion of virus in the faeces and antibody titres in the serum. The results showed that although all chicks appeared to be susceptible to IBV infection, the most severe clinical response was observed following infection at 2-week-old. Likewise, whilst the virus was also recovered from the faeces of all the chicks infected, the duration of viral excretion was longest in the 2-week-old chicks. A high antibody titre was detected at 4 weeks post infection (PI) and was maintained for at least another 16 weeks in the 4- and 6-week-old chicks. In contrast, a low antibody titre was detected only between 8 to 12 weeks PI in the 2-week-old chicks. Thereafter, no antibody was detected despite the presence of clinical signs.

Relative frequencies of G (VP7) and P (VP4) serotypes determined by polymerase chain reaction assays among Japanese bovine rotaviruses isolated in cell culture.

The relative frequencies of both the G (VP7) and P (VP4) serotypes of 40 bovine rotaviruses isolated in cell culture from diarrheic calves in Japan between January 1983 and February 1991 were determined by recently developed polymerase chain reaction assays. Isolates with G serotype 6 and P serotype 5 (UK-like strains) were most frequently found (42.5%) followed by isolates with G6P11 (17.5%), G6P1 (10%), or G10P5 (10%). Isolates with G10P11 (B223-like strains) were least frequently found (7.5%). The presence of various combinations of G and P serotypes suggests frequent reassortment in nature among bovine rotaviruses.

Characterization of Yersinia pseudotuberculosis serogroups O9, O10 and O11; subdivision of O1 serogroup into O1a, O1b, and O1c subgroups.

In this study, three new antigens (O9, O10 and O11) of Yersinia pseudotuberculosis are described. The O1 antigen is further subdivided into O1a, O1b and O1c. The methods used to prepare specific antisera for O-antigen identification are also described. Furthermore, the H antigens of these new serogroups are determined and their biochemical characteristics analysed. The antigenic formulae of the known serogroups within the basic antigenic scheme introduced by the authors' laboratories are presented.

Necrotic colitis associated with Entamoeba histolytica infection in a cat.

A 3-year-old Persian cat developed bloody diarrhoea. On histological examination, a marked necrotic colitis with a large number of invading protozoan parasites was observed. The protozoan was identified as Entamoeba histolytica by light and electron microscopy. This is the first report describing spontaneous amoebiasis in cats.

Characterization of an amorphous and soluble hemagglutinin from Yersinia pseudotuberculosis.

Yersinia pseudotuberculosis which were screened out depending on auto-agglutination and Ca2+ dependency, were examined for their production of hemagglutinin (HA), and its purification and characterization were performed. The HA with a broad reactivity with various mammalian erythrocytes was recovered from the culture supernatant of these strains grown at 37 C but not 25 C. HAs from two strains, R148R and T1040, were purified by salt precipitation, gel filtration and anion-exchange chromatography by HPLC. Both purified HAs were cysteine-deficient acidic protein with an apparent molecular weight in the range of 15,000 to 16,000. N-terminal amino acid sequences of the first 25 residues were found to share 12% identity with that of afimbrial adhesin from enterotoxigenic Escherichia coli 2230. Immunoelectron microscopy and immunodiffusion test with polyclonal antiserum raised against the purified R148RHA demonstrated that the HA was associated with the amorphous aggregates which were detached from bacteria. These results suggest that the HA of Y. pseudotuberculosis belongs to a third type of HA produced by the yersinial species.

Enteric adenovirus type 41 isolates: cloning, physical maps and diversity in restriction enzyme cleavage pattern.

Adenovirus (Ad) type 40 and 41 DNAs were directly extracted from stool specimens of children with gastroenteritis. Two new strains of Ad41, Sanekata and Ehime strain, were cloned and their restriction maps were constructed. The left terminal end of the cloned Ad41 genome, EcoRI-E fragment of the Sanekata strain and EcoRI-F fragment of the Ehime strain, had transforming ability in rat 3Y1 cells. Only one of the 35 isolates of Ad40 tested showed a different restriction profile, while three different restriction profiles were found in DNAs from Ad41 isolates.

Detection of porcine rotavirus in stools by a latex agglutination test.

We developed a simple agglutination test for the detection of porcine rotavirus in stools from pigs with diarrhea. The virus was detected with high sensitivity and specificity by a slide agglutination test using latex particles coated with antibody against the porcine rotavirus strain OSU (LA-antiOSU). The agglutination of LA-antiOSU with OSU on a glass slide was evident macroscopically within 2 min. The sensitivity of this latex agglutination (LA) test was four times higher than that of the electron microscope method. The LA test is available for the rapid diagnosis of porcine rotavirus infections.

Detection of adenovirus type41 in stool samples by a latex agglutination method.

We have developed a simple agglutination (LA) method for the detection of enteric adenovirus (EAd) in stool samples from infants with acute gastroenteritis. Ad type 41 (Ad41) was detected with high sensitivity and specificity by a slide agglutination test using latex particles coated with antiAd41 antibody (LA-antiAd41). The agglutination of LA-antiAd41 with Ad41 on a glass slide was evident macroscopically within 2 min. The sensitivity of the LA method was four times higher than that of the EM method.

Selection of variants of avian infectious bronchitis virus showing tropism for different organs.

Avian infectious bronchitis virus strain Kagoshima-34 isolated from the kidneys of a chicken that died of nephrosis/nephritis lost its nephropathogenicity during intratracheal passage in SPF chickens. The resultant virus acquired stronger respirotropism but reduced tropism for kidneys. On the other hand strain Tottori-2 isolated from the trachea of a chicken suffering from severe respiratory disease did not lose its respirotropism after serial intravenous passage in SPF chickens. The serological properties of the passaged virus were investigated by virus neutralisation test. The antibody titres of both strains of virus fluctuated with progressive passage. The serological properties of the virus isolated from respiratory organs were not necessarily the same as those of the isolates made from the kidneys.

Human rotavirus detection by agglutination of antibody-coated erythrocytes.

We sensitized sheep erythrocytes (SRBC) with antibodies against human rotavirus strain Wa (SRBC-antiWa) and antibodies against calf rotavirus strain NCDV (SRBC-antiNCDV). These were readily agglutinated in the presence of homologous antigens, i.e., human rotavirus and calf rotavirus. By the hemagglutination of SRBC-antiWa and SRBC-antiNCDV (reverse passive hemagglutination [RPHA]), titration of rotavirus in extracts from feces of children suffering from diarrhea (61 specimens) was carried out. We found that the ratio of titers determined with SRBC-antiWa and SRBC-antiNCDV varied remarkably from specimen to specimen. This indicated that the antigenic determinants on human rotavirus in patients feces cross-react with antibodies against NCDV to varying extents. To express the cross-reactivity of human rotavirus with antibodies to NCDV, we propose a Wa/NCDV rotavirus index which can be calculated from the RPHA titer with SRBC-antiWa and SRBC-antiNCDV as follows: Wa/NCDV rotavirus index = (antiWa-RPHA titer of specimen/antiWa-RPHA titer of NCDV)/(antiNCDV-RPHA titer of specimen/antiNCDV-RPHA titer of NCDV).

Detection of rotavirus antibody by inhibition of reverse passive hemagglutination.

A reverse passive hemagglutination inhibition (RPHI) test was developed for detecting rotavirus antibody in patients' sera. Sheep erythrocytes coated with guinea pig antibody against Nebraska calf diarrhea virus (NCDV) were readily hemagglutinated by NCDV in a reaction called reverse passive hemagglutination (RPHA). Inhibition of this RPHA reaction was used to detect the presence of rotavirus antibody in patients' sera which cross-reacted with NCDV. The sensitivity of RPHI was consistently at least 10 times greater than that of the complement fixation test for detection of rotavirus antibody in patients' sera. Since immunoglobulin M (IgM) antibody activity detected by RPHI was destroyed by pretreatment of serum with dithiothreitol (DDT), whereas DTT-resistant antibodies such as IgG remained unchanged, the titer of IgM antibody could be distinguished from that of DTT-resistant antibody by comparing the results of two RPHI tests performed with and without DTT pretreatment. From the IgM antibody response pattern, primary and secondary rotavirus infections could be distinguished.

Detection of rotavirus in faeces by latex agglutination.

Human rotavirus (HRV) in faeces of patients may be readily detected with high sensitivity and specificity using latex agglutination (LA) on a glass slide by making use of the cross-reactivity of anti-calf rotavirus (CRV) antibody. Latex particles were coated with anti-CRV immunoglobin. The antibody coated particles (AC-L) are specifically agglutinated by both CRV and HRV, and the agglutination is evident macroscopically within a minute. To examine the sensitivity and reliability of the LA method compared to other methods, HRV in faecal extracts of 48 infants with acute gastroenteritis was sought by the LA, reversed passive haemagglutination (RPHA) and electron microscope (EM) methods. Samples positive by the EM method were all positive by the LA method, and samples negative by EM were all negative by LA. The LA method is suitable for application as a simple clinical diagnostic test.