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Biomedical subjects

L K Riley

Publications and source records attributed to L K Riley.

At least 55 records · Page 3Linked to original sources
PubMed1996

Isolation of a novel Helicobacter species, Helicobacter cholecystus sp. nov., from the gallbladders of Syrian hamsters with cholangiofibrosis and centrilobular pancreatitis.

A filamentous, gram-negative, motile bacterium with a single polar sheathed flagellum was isolated from gallbladders of hamsters with cholangiofibrosis and centrilobular pancreatitis. Bacteria grew under microaerophilic conditions at 37 and 42 degrees C, were oxidase, catalase, arginine aminopeptidase, and L-arginine arylamidase positive, reduced nitrate to nitrite, were resistant to cephalothin, and exhibited intermediate susceptibility to nalidixic acid. Sequence analysis of the 16S rRNA gene indicated that the bacterium was a novel member of the Helicobacter genus, most closely related to Helicobacter pametensis. We propose to name this bacterium Helicobacter cholecystus. In epidemiologic studies, isolation of H. cholecystus correlated strongly with the presence of cholangiofibrosis and centrilobular pancreatitis; however, further studies are needed to define the role of this bacterium in pathogenesis.

Animals↗
PubMed1996

Expression of recombinant parvovirus NS1 protein by a baculovirus and application to serologic testing of rodents.

A recombinant baculovirus containing the NS1 gene of minute virus of mice was constructed. Optimal expression of the recombinant NS1 protein (rNS1) was achieved by infecting Trichoplusa ni High Five cells at a multiplicity of 10 and incubating them for 72 h postinfection. An enzyme-linked immunosorbent assay (ELISA) with rNS1 as the antigen was evaluated for serologic testing of laboratory rodents. The rNS1 ELISA proved to be a more sensitive method for the detection of antibodies to recently recognized rodent parvovirus species (mouse orphan parvovirus and rat orphan parvovirus) and prototypic parvovirus species (minute virus of mice, Kilham's rat virus, and H-1) than were conventional parvovirus ELISAs that use whole parvovirus virions.

Amino Acid Sequence↗
PubMed1996

Identification of murine helicobacters by PCR and restriction enzyme analyses.

Three murine helicobacter species have recently been identified: Helicobacter hepaticus, Helicobacter muridarum, and Helicobacter bilis. Infections with H. hepaticus and H. bilis have been associated with hepatitis and hepatic neoplasia. In this study, oligonucleotide primers were designed from regions of the 16S rRNA gene that are conserved among members of the Helicobacter genus. The assay amplified the expected 374-bp product from all three rodent Helicobacter species and was able to detect as little as 5 pg of H. hepaticus, H. bilis, or H. muridarum DNA. The specificity of the reaction was determined by testing cecal DNA from uninfected mice and mice with documented Helicobacter infections and by testing DNA from other bacterial genera. A product of the expected size was generated with cecal DNA from Helicobacter-infected mice but not with DNA from uninfected mice. With the exception of that of "Flexispira rappini, " which is closely related to the Helicobacter genus, DNA from other bacterial genera was not amplified with the Helicobacter genus-specific primers. MboI, MaeI, and HhaI restriction enzyme analyses of the amplified product were able to differentiate among the murine Helicobacter species but could not differentiate H. bilis from "F. rappini." To distinguish H. bilis, a reverse primer based on H. bilis 16S rRNA sequence was designed. PCR with the H. bilis-specific reverse primer (Hbr) and the Helicobacter genus-specific forward primer (H276f) amplified H. bilis DNA but not DNA from "F. rappini" or other rodent helicobacters. Examination of a large number of murine cecal tissues with this combination of PCR assays and restriction enzyme analyses indicated that H. hepaticus and H. bilis infections are widespread in laboratory mouse and rat colonies.

Animals↗
PubMed1996

Lesions of experimental genital Tritrichomonas foetus infections in estrogenized BALB/c mice.

Ninety-seven BALB/c mice were inoculated intravaginally with 8.0 x 10(5) Tritrichomonas foetus organisms, using either isolate ATCC 30003 or field isolate MU Y22 2 days after estrogenization with 15 micrograms 17 beta-estradiol. Reproductive tracts were examined at several time points post-inoculation to determine gross and histologic responses to trichomonad infection as compared to estrogenized, uninfected control animals. The two isolates varied greatly in ability to maintain chronic infection; no ATCC 30003-inoculated animals remained culture-positive beyond 7 weeks post-inoculation, whereas MU Y22-inoculated animals were infected for greater than 26 weeks. Lesions were seen in 40-60% of animals prior to 10 weeks post-inoculation and included moderate uterine dilation and glandular atrophy, uterine gland abscesses, pyometra, intramural perivascular lymphoid infiltrates, and ovarian bursitis. The severity of lesions was independent of the T. foetus isolate. Lesions became more severe at 10 weeks post-inoculation, and at 10 and 26 weeks post-inoculation, lesions were seen in 60% and 75% of animals, respectively. In addition to lesions described above, epithelial changes were marked at these late necropsies, including ulceration, flattening, hypertrophy, and squamous metaplasia. The lesions seen in these mice closely resemble those described in natural bovine infection, suggesting that the estrogenized BALB/c mouse is an excellent model for study of bovine trichomoniasis.

Administration, Intravaginal↗
PubMed1996

A novel presentation of Clostridium piliforme infection (Tyzzer's disease) in nude mice.

Clostridium piliforme infection (Tyzzer's disease) was diagnosed in a colony of nude mice. Because spontaneous Tyzzer's disease had not been reported in nude mice, a study was undertaken to better define the clinicopathologic features of this disease outbreak. Sixty homozygous nude (nu/nu) females, 10 nu/nu males, and 10 heterozygous nude (nu/+) females were observed for signs of disease. Over a 3-month period, 43% of the nu/nu mice died or manifested clinical signs of disease and were euthanized, but nu/+ mice remained healthy. Clinical signs of disease were infrequently observed in nu/nu mice and, when evident, were followed by rapid deterioration and death. Gross and histologic lesions, including severe hepatic and intestinal necrosis associated with C. piliforme, were observed only in clinically affected animals. Clostridium piliforme isolated from diseased livers had marked cytotoxicity in in vitro assays. This outbreak is unique in that, contrary to a previous experimental report, nu/nu mice had increased susceptibility to Tyzzer's disease, suggesting that T cells may play an important role in host defenses against C. piliforme infection. In addition, this is the first report of a toxigenic isolate of C. piliforme recovered from mice. The cytotoxin produced by the isolate may have contributed to the severity of clinical disease and lesions.

Animals↗
PubMed1996

Rodent parvovirus infections.

Parvoviruses are among the most common infectious agents of laboratory rodents and major impediments to rodent-based research. The original prototypic rodent parvoviruses-minute virus of mice, rat virus, and H-1 virus-have recently been joined by biologically and antigenically distinct parvoviruses in mice, rats, and hamsters. Recognition of the increased diversity of rodent parvoviruses presents new challenges for determining the impact of parvovirus infection on research and for detecting, preventing, and eliminating infection. This review summarizes current knowledge about rodent parvoviruses and parvovirus infections, highlighting recent research on newly isolated virus strains.

Animals↗
PubMed1995

Tritrichomonas foetus: comparison of isolate virulence in an estrogenized mouse model.

Previous studies indicated that Tritrichomonas foetus isolate ATCC 30003 was capable of maintaining only short-term genital infection in estrogenized BALB/c mice. In the present study, the ability of eight T. foetus isolates to establish and maintain infections in intravaginally inoculated estrogenized BALB/c mice was examined. All isolates were found to be equally capable of establishing genital infections but varied greatly in ability to maintain infections. One isolate maintained infection for less than 7 weeks, four isolates maintained intermediate infections lasting less than 13 weeks, and three isolates maintained chronic infections of greater than 26 weeks. Varying the number of trophozoites inoculated intravaginally decreased the ability of isolates to establish infection but did not affect maintenance of infection. Prolonged passage of T. foetus isolates either in vivo in an estrogenized nu/nu BALB/c mouse or by in vitro culture failed to affect their ability to maintain infection, suggesting that virulence was parasite-dependent and not related to environment-induced changes. Co-infection of estrogenized mice with isolates ATCC 30003 and MU Y32 failed to increase the length of ATCC 30003 infections or decrease the length of isolate MU Y32 infections. Taken together these results indicate that T. foetus isolates vary greatly in virulence in estrogenized BALB/c mice and provide evidence suggesting that maintenance of infection is a parasite-controlled factor.

Animals↗
PubMed1995

Seroanalysis of Tyzzer's disease in horses: implications that multiple strains can infect Equidae.

A monoclonal antibody based competitive inhibition assay was used to detect antibodies in horse sera to purified flagellar antigens from distinct Clostridium piliforme isolates. Sequential absorption of hyperimmune rat serum to C. piliforme isolate E (horse-origin isolate), a positive C. piliforme-immune horse serum, and other suspected immune horse sera with unrelated bacteria or C. piliforme isolates E or isolate R1 (rat-origin isolate) alone demonstrated the specificity of this assay for C. piliforme. This specificity was associated with the inhibition of monoclonal antibody binding to C. piliforme flagella, rather than to C. piliforme somatic antigens, by horse immunoglobulins partially purified from serum. Thirty seven of 162 horse sera possessed large amounts of antibody to the flagella of C. piliforme isolate E and 23 of the 162 had large amounts of antibody to the flagella of C. piliforme isolate R1; 9 of the sera possessed large amounts of antibody to both flagellar antigens. Absorption of these sera with isolate E or R1 demonstrated that antibody reactivity to the 2 C. piliforme isolates was isolate-specific and not due to antibody cross-reactive with both isolates. These results suggest that infection of horses with C. piliforme may be relatively common; and that they are susceptible to at least 2 distinct strains.

Analysis of Variance↗
PubMed1995

Detection of newly recognized rodent parvoviruses by PCR.

Several autonomous parvovirus isolates distinct from the prototypic rodent parvoviruses have recently been identified. These include variants of a mouse orphan parvovirus (MOPV) and a hamster isolate designated hamster orphan parvovirus (HOPV). In this study, a PCR primer set specific for these newly identified rodent parvoviruses was designed on the basis of DNA sequence comparisons of these isolates with other autonomous parvoviruses. The specificity of the primer set was determined by testing viral preparations of seven different parvoviruses and eight other viruses known to infect rodents. The PCR assay amplified the expected 260-bp product only in the presence of DNA from MOPV, HOPV, or LuIII a parvovirus of unknown species origin. The assay was able to detect as little as 10 pg of MOPV viral DNA or 1 pg of HOPV viral DNA, and it was able to detect MOPV in tissues from naturally infected mice and HOPV in tissues from experimentally infected hamsters. In contrast, the 260-bp product was not amplified from tissues of MOPV-negative mice or mock-infected hamsters. Our findings indicate that this PCR assay provides a rapid, specific, and sensitive method for the detection of MOPV in mice, HOPV in hamsters, and MOPV and HOPV in cell culture systems and that it may also be useful for the detection of LuIII contamination of cell culture systems.

Animals↗
PubMed1995

Detection of H-1 parvovirus and Kilham rat virus by PCR.

H-1 virus and Kilham rat virus (KRV) are autonomous parvoviruses which generally cause subclinical infections in rats and can cause persistent infections in cell cultures. In this study, primer sets specific for either H-1 or KRV were designed on the basis of DNA sequence comparisons of the rodent parvoviruses. The specificities of the H-1 and KRV-specific primer sets were determined by testing viral preparations of seven different parvoviruses and nine other viruses known to infect rodents. The H-1-specific PCR assay amplified the expected 254-bp product only in the presence of H-1 viral DNA and was able to detect as little as 100 fg of H-1 viral DNA. The KRV-specific PCR assay generated the expected 281-bp product only when KRV viral DNA was used as the template and was able to detect as little as 10 pg of KRV viral DNA. Each assay was able to detect its respective virus in tissues from rats experimentally infected with H-1 or KRV. In contrast, no product was amplified by either assay with tissues from mock-infected rats. Our findings indicate that these PCR assays provide rapid, specific, and sensitive methods for the detection of H-1 or KRV infection in rats and cell culture systems.

Animals↗
PubMed1995

Expression of Sendai virus nucleocapsid protein in a baculovirus expression system and application to diagnostic assays for Sendai virus infection.

The most common diagnostic technique for the detection of Sendai virus infection in rodents is serological evaluation by enzyme-linked immunosorbent assay (ELISA) with semipurified preparations of whole virions as antigens. This assay often suffers from a lack of specificity. The goal of the present project was to develop more specific antigens for use in diagnostic testing by producing recombinant antigens in insect cells. To identify viral proteins immunoreactive in multiple laboratory rodent species, Western blots (immunoblots) of viral polypeptides were probed with immune sera from mice, rats, and hamsters. The nucleocapsid protein (NP) reacted with immune sera from all species tested. Therefore, the NP gene was selected for cloning and expression in a baculovirus. To construct the recombinant, complementary DNA was synthesized by reverse transcription PCR from Sendai virus RNA with primers from the 5' and 3' termini of the NP-coding region. Amplified DNA was cloned into a baculovirus transfer vector (pBlueBacHis A) and was cotransfected with wild-type baculovirus into insect cells. Baculovirus recombinants containing the NP gene were identified by PCR. Evaluation of the recombinant proteins expressed in insect cells by Western blot analysis revealed specific reactivity with immune sera. In comparison with conventional ELISAs that use whole virions as the antigen, ELISAs that use recombinant NP were more specific.

Animals↗
PubMed1995

Colonization of the tracheal epithelium of pigs by filamentous bacteria resembling cilia-associated respiratory bacillus.

Warthin Starry staining revealed filamentous bacteria colonizing the tracheal epithelium of 41 of 88 (46.6%) pigs submitted for necropsy at 2 midwestern veterinary diagnostic laboratories. The bacteria were interspersed between and oriented parallel to the cilia. In 4 of 4 colonized pig tracheas, filamentous bacteria were demonstrated by transmission electron microscopy. The bacteria were approximately the same length and diameter as cilia, and in areas of heavy colonization the bacteria outnumbered cilia. The filamentous bacteria were similar in location and morphologic characteristics to cilia-associated respiratory (CAR) bacilli of rats, mice, rabbits, and cattle. Results of immunoperoxidase staining and polymerase chain reaction analysis indicated that the pig CAR bacillus is a different bacterium than the rat CAR bacillus. Rat CAR bacillus causes chronic respiratory disease in rats and mice. The association, if any, between pig CAR bacillus and swine respiratory disease is unknown.

Animals↗
PubMed1995

Characterization of cilia-associated respiratory bacillus in rabbits and analysis of the 16S rRNA gene sequence.

The cilia-associated respiratory (CAR) bacillus is an unclassified, gram-negative bacterium that has been implicated as an etiologic agent of respiratory tract disease in laboratory rodents. A morphologically and antigenically similar organism has been identified in rabbits and is thought to be a related bacterium, although clinical signs of disease and histologic lesions are absent in infected rabbits. To compare the pathogenicity of rat- and rabbit-origin CAR bacillus isolates in rabbits, neonatal rabbits were experimentally infected with CAR bacillus isolates obtained from an infected rat and rabbit. Rabbits experimentally inoculated with rabbit-origin CAR bacillus had a nasal discharge, seroconverted and developed histologic lesions, whereas rabbits inoculated with rat-origin CAR bacillus seroconverted but did not have evidence of colonization of the respiratory tract. The CAR bacillus isolates were further examined at the genetic level by sequencing 1,261 base pairs of the 16S rRNA gene from six CAR bacillus isolates obtained from infected rabbits. A consensus sequence was obtained and compared with the analogous gene sequence data from rat-origin CAR bacillus isolates. Results indicated that these two organisms are distinctly different, with only 48.8% sequence homology. Comparison of the rabbit-origin 16S rRNA gene sequence with the database Genbank indicated that the organism is most closely related to members of the genus Helicobacter. Bacteria with the highest percentage of similarity with the rabbit-origin CAR bacillus were Helicobacter sp. strain Seymour and H. felis, with 91.1 and 90.8%, respectively. Findings of this study indicate that CAR bacillus isolates from rats and rabbits are host-specific and are different bacteria that belong to distinct genera.

Animals↗
PubMed1995

Cerebrospinal larva migrans due to Baylisascaris procyonis in a guinea pig colony.

Four guinea pigs from a colony of approximately 50 animals were examined for progressive neurologic disease of 5 days' duration. Signs of neurologic dysfunction included cachexia, stupor, hyperexcitability, lateral recumbency, and opisthotonos. Results of gross pathologic, microbiologic, and serologic examinations were unremarkable. Histologic examination of cerebral and cerebellar sections revealed multifocal malacia and regions of eosinophilic granulomatous inflammation. Cross-sections of nematode larvae, identified as Baylisascaris sp., most likely B. procyonis, the raccoon ascarid, were seen in the brain of some affected animals. An intact Baylisascaris larva was recovered from a symptomatic animal when cerebral tissue was processed by the Baermann extraction technique. Results of further investigation indicated that wood shavings used for the guinea pigs had been contaminated by raccoon feces, some of which contained numerous B. procyonis eggs. The bedding source for this colony was changed and, to date, no new cases of neurologic disease have been seen. This report emphasizes the potential insidious entrance of B. procyonis into well-managed laboratory animal facilities.

Animals↗
PubMed1994

Detection of cilia-associated respiratory bacillus by PCR.

The cilia-associated respiratory (CAR) bacillus is an unclassified, gram-negative, motile bacterium that has been implicated as an etiologic agent of respiratory disease in laboratory rodents. In the present study, approximately 1,200 bases of the 16S rRNA gene from three CAR bacillus isolates were sequenced. CAR bacillus-specific primers were designed on the basis of the 16S rRNA gene sequence and used in a PCR assay. The PCR assay detected as little as 500 fg of purified CAR bacillus DNA. The expected 267-bp DNA fragment was amplified from respiratory tissue of frozen, formalin-fixed, and paraffin-embedded samples from experimentally and naturally infected rats and mice. In contrast, no product was amplified from respiratory tissues of sham-infected experimental animals or animals that were serologically or histopathologically negative for the CAR bacillus. Our findings indicate that this PCR assay is a rapid, specific, and sensitive detection method for the diagnosis of CAR bacillus infection in rats and mice.

Animals↗