Janet Macinnes - Academia.edu (original) (raw)

Papers by Janet Macinnes

Virology, 1986

Mouse mammary tumor virus (MMTV) is integrated in the genome of most mice as an endogenous provir... more Mouse mammary tumor virus (MMTV) is integrated in the genome of most mice as an endogenous provirus. Two of these MMTV proviral loci (Mtv-1 and Mtv-2) are associated with virus expression and tumorigenicity. We prepared restriction endonuclease maps of the endogenous MMTV proviruses in two strains, DBA and GR, which contain the Mtv-1 and Mtv-2 loci, plus a third strain, NFS, which has a low mammary tumor incidence. We find that all these mouse strains have certain MMTV loci in common even though their origins are widely divergent. We also find that some integrated MMTV proviruses appear to have undergone alterations or deletions when compared with MMTV exogenous proviral DNA. We have thus made a comprehensive characterization of MMTV loci in these mouse strains which could serve as a basis for the study of their differences in expression.

Research Square (Research Square), Apr 21, 2021

Bovine mastitis is the costliest diseases on dairy farms and is caused by different Staphylococcu... more Bovine mastitis is the costliest diseases on dairy farms and is caused by different Staphylococcus species. However, staphylococci associated with clinical mastitis infections are different from subclinical ones, indicating a complex mechanism related to bovine mastitis pathogenesis. Here, we performed genomic analyses to determine the prevalence of adhesion, bio lm, and regulatory genes in 478 staphylococcal spp. associated with clinical and subclinical mastitis deposited in public databases. The most prevalent adhesin genes were the ebpS, atl, pls, sasH and sasF genes found in both clinical and subclinical isolates. However, the ebpS gene is absent in subclinical isolates of Staphylococcus arlettae, S. succinus, S. sciuri, S. equorun, S. galinarum, and S. saprophyticus. In constrast, the coa, eap, emp, efb, and vWbp genes were present more frequently in clinical mastitis isolates and highly correlated with the presence of the icaABCD and icaR bio lm genes. We also revealed that many adhesins, bio lm, and associated regulatory genes were potentially horizontally disseminated between clinical and subclinical isolates. Taken together, our results indicate that several adhesins, bio lm, and regulatory-related genes have been overlooked in previous studies and that these virulence factors may arise in staphylococcal species not generally associated with clinical mastitis by horizontal gene transfer.

Journal of Clinical Microbiology, Oct 1, 2000

Journal of Fish Diseases, Aug 3, 2018

Flavobacterium psychrophilum, the causative agent of bacterial cold-water disease (BCWD) in fresh... more Flavobacterium psychrophilum, the causative agent of bacterial cold-water disease (BCWD) in freshwater-reared salmonids, is also a common commensal organism of healthy fish. The virulence potential of F. psychrophilum isolates obtained from BCWD cases in Ontario between 1994 and 2009 was evaluated. In preliminary infection trials of rainbow trout juveniles, significant differences (0% to 63% mortality) in the virulence of the 22 isolates tested were noted following intraperitoneal injection with 108 cfu/fish. A highly virulent strain, FPG 101, was selected for further study. When fish were injected intraperitoneally with a 106 , 107 or 108 cfu/fish of F. psychrophilum FPG 101, the 108 cfu/fish dose produced significantly greater mortality (p < 0.05). The bacterial load in spleen samples collected from fish every 3 days after infection was determined using rpoC quantitative polymerase chain reaction amplification and by plate counting. Bacterial culture and rpoC qPCR were highly correlated (R2 = 0.92); however, culture was more sensitive than the qPCR assay for the detection of F. psychrophilum in spleen tissue. Ninety-seven per cent of the asymptomatic and the morbid fish had splenic bacterial loads of <2.8 log10 gene/copies and >3.0 log10 gene copies/reaction, respectively, following infection with 108 cfu/fish.

PubMed, Apr 1, 1999

In recent years, Actinobacillus suis, Haemophilus parasuis, and Streptococcus suis have emerged a... more In recent years, Actinobacillus suis, Haemophilus parasuis, and Streptococcus suis have emerged as important pathogens of swine, particularly in high health status herds. Their association with a wide range of serious clinical conditions and has given rise to the moniker "suis-ide diseases." These organisms are early colonizers and, for that reason, are difficult to control by management procedures such as segregated early weaning. Vaccination, serodiagnostic testing, and even serotyping are complicated by the presence of multiple serotypes, cross-reactive antigens, and the absence of clear markers for virulence. In this review, we discuss our current understanding of the pathogenesis, epidemiology, and management of the causative agents of the "suis-ide diseases" of swine.

Journal of Aquatic Animal Health, Mar 1, 2010

Flavobacterium psychrophilum is the etiological agent of bacterial coldwater disease (BCWD), an i... more Flavobacterium psychrophilum is the etiological agent of bacterial coldwater disease (BCWD), an important disease in the Ontario fish farming industry and in finfish aquaculture in temperate waters worldwide. The development of antimicrobial resistance by F. psychrophilum is a concern because management of outbreaks of BCWD often requires the use of antibiotics. Seventy‐two isolates of F. psychrophilum collected over a 16‐year period from farmed salmonids with clinical signs of BCWD were tested for susceptibility to 10 antimicrobial agents using cation‐adjusted Mueller–Hinton broth in custom Trek Sensititre susceptibility plates for aquaculture. The minimum inhibitory concentrations (MICs) for the isolates were determined by means of a broth microdilution antimicrobial susceptibility testing method established by the Clinical and Laboratory Standards Institute. Most of the F. psychrophilum isolates had decreased susceptibility to two of the four antibiotics licensed for use in Ontario (i.e., ormetoprim–sulfadimethoxine [≥0.5/9.5 μg/mL for 93% of isolates] and trimethoprim–sulfamethoxazole [≥0.25/4.8 μg/mL for 89% of isolates]). High MIC values (≥2 μg/mL) were obtained for florfenicol and oxytetracycline in 53% and 61% of the isolates, respectively, and 83% of the isolates were relatively susceptible (≤16 μg/mL) to erythromycin. The MIC values were also high for ampicillin, oxolinic acid, and gentamicin.

Animal Health Research Reviews, Jun 1, 2012

Frontiers in Microbiology, Nov 7, 2022

Staphylococcus aureus causes nosocomial and intramammary infections in humans and cattle, respect... more Staphylococcus aureus causes nosocomial and intramammary infections in humans and cattle, respectively. A large number of virulence factors are thought to play important roles in the pathogenesis of this bacterium. Currently, genome-wide and data-analysis studies are being used to better understand its epidemiology. In this study, we conducted a genome wide comparison and phylogenomic analyses of S. aureus to find specific virulence patterns associated with clinical and subclinical mastitis strains in cattle and compare them with those of human origin. The presence/absence of key virulence factors such as adhesin, biofilm, antimicrobial resistance, and toxin genes, as well as the phylogeny and sequence type of the isolates were evaluated. A total of 248 genomes (27 clinical mastitis, 43 subclinical mastitis, 21 milk, 53 skin-related abscesses, 49 skin infections, and 55 pus from cellulitis) isolated from 32 countries were evaluated. We found that the cflA, fnbA, ebpS, spa, sdrC, coa, emp, vWF, atl, sasH, sasA, and sasF adhesion genes, as well as the aur, hglA, hglB, and hglC toxin genes were highly associated in clinical mastitis strains. The strains had diverse genetic origins (72 protein A and 48 sequence types with ST97, ST8 and ST152 being frequent in isolates from clinical mastitis, abscess, and skin infection, respectively). Further, our phylogenomic analyses suggested that zoonotic and/or zooanthroponotic transmission may have occurred. These findings contribute to a better understanding of S. aureus epidemiology and the relationships between adhesion mechanisms, TYPE

Genomics, 2019

Actinobacillus spp. are Gram-negative bacteria associated with mucosal membranes. While some are ... more Actinobacillus spp. are Gram-negative bacteria associated with mucosal membranes. While some are commensals, others can cause important human and animal diseases. A. pleuropneumoniae causes severe fibrinous hemorrhagic pneumonia in swine but not systemic disease whereas other species invade resulting in septicemia and death. To understand the invasive phenotype of Actinobacillus spp., complete genomes of eight isolates were obtained and pseudogenomes of five isolates were assembled and annotated. Phylogenetically, A. suis isolates clustered by surface antigen type and were more closely related to the invasive A. ureae, A. equuli equuli, and A. capsulatus than to the other swine pathogen, A. pleuropneumoniae. Using the LS-BSR pipeline, 251 putative virulence genes associated with serum resistance and invasion were detected. To our knowledge, this is the first genome-wide study of the genus Actinobacillus and should contribute to a better understanding of host tropism and mechanisms of invasion of pathogenic Actinobacillus and related genera.

Journal of Dairy Science, Dec 1, 2019

The aim of this study was to determinate whether coagulase-negative staphylococci (CNS) from buff... more The aim of this study was to determinate whether coagulase-negative staphylococci (CNS) from buffalo milk or the milking environment possess virulence factors that are associated with intramammary infections or antimicrobial resistance. Milk samples (n = 320) from 80 lactating buffalo were evaluated for clinical and subclinical mastitis by physical examination, the strip cup test, California Mastitis Test (CMT), and somatic cell count (SCC) over a 4-mo period. In addition, swabs were obtained from the hands of consenting milkers (16), liners (64), and from the mouths (15) and nostrils (15) of buffalo calves. No clinical cases of mastitis were observed; however, CMT together with SCC results indicated that 8 animals had subclinical mastitis. Eighty-four CNS isolates were identified by MALDI-TOF MS and cydB real-time PCR (qPCR) and then evaluated by qPCR for presence of the eta, etb, sea, sec, cna, seb, sei, seq, sem, seg, see, and tst toxin genes, adhesion-and biofilm-associated genes (eno, ebps, fib, fnbA, coa), and the methicillin resistance gene (mecA). Resistance to antibiotics commonly used for mastitis treatment in Brazil was determined using the Kirby-Bauer test. Two strains were positive for the see and eta toxin genes; and mecA (1), eno (27), ebps (10), fnbA (10), and coa (5) genes were also detected. A notable number of isolates were resistant to erythromycin (30), penicillin (26), and cotrimoxazole (18); importantly, 10 vancomycin-resistant isolates were also detected. A smaller number of isolates were resistant to rifampicin (8), oxacillin (7), clindamycin (5), cefepime (4), tetracycline (3), ciprofloxacin (2), and chloramphenicol (1), and none were resistant to gentamicin or ciprofloxacin. Isolates with resistance to 2 (13 isolates), 3 (3), 4 (3), 5 (1), and 6 (1) antibiotics were detected. Taken together, our findings suggest that CNS isolates may not be a significant cause of clinical or even subclinical mastitis in buffaloes, but they may be a reservoir of virulence and antibiotic resistance genes.

Infection and Immunity, Nov 1, 1989

This article describes the molecular cloning and expression of a hemolysin gene from a serotype 1... more This article describes the molecular cloning and expression of a hemolysin gene from a serotype 1 strain of Actinobacillus pleuropneumoniae. The hemolysin was a thermolabile protein with an apparent molecular weight of 29,500 (29.5K hemolysin). Unlike expression of the recently described 105K hemolysin of A. pleuropneumoniae (J. Frey and J. Nicolet, FEMS Microbiol. Lett. 55:41-46, 1988), expression of this hemolysin was not regulated by Ca2+. Antiserum prepared against the 105K hemolysin did not neutralize the activity of the 29.5K hemolysin; conversely, antiserum prepared against the 29.5K hemolysin did not neutralize the activity of the 105K hemolysin. The hemolytic activity was not neutralized with antisera against hemolytic Escherichia coli, Streptococcus agalactiae, or purified streptolysin 0, but antisera prepared against recombinants containing the 29.5K gene and convalescent pig sera abrogated hemolytic activity. Although hemolytic activity could be detected in several strains of E. coli K-12 and in minicells expressing several different constructs encoding the 29.5K hemolysin, we could not rigorously exclude the possibility that the gene which we have isolated encodes a regulator of hemolytic activity rather than a hemolysin per se.

PubMed, Apr 1, 2014

A real-time polymerase chain reaction (PCR) assay of the outer membrane protein (OMP) P2 gene was... more A real-time polymerase chain reaction (PCR) assay of the outer membrane protein (OMP) P2 gene was developed and used to test 97 putative Haemophilus parasuis pure cultures and 175 clinical tissue samples. With standard culture isolation as the gold standard, the diagnostic sensitivity and specificity of the PCR assay were determined to be 83% and 80%, respectively.

Veterinary Microbiology, Nov 1, 2016

Actinobacillus suis is an opportunistic pathogen that resides in the tonsils of the soft palate o... more Actinobacillus suis is an opportunistic pathogen that resides in the tonsils of the soft palate of swine. Unknown stimuli can cause this organism to invade the host, resulting in septicaemia and sequelae including death. To better understand its pathogenesis, the expression of several adhesin genes was evaluated by semi-quantitative real-time PCR in A. suis grown in conditions that mimic the host environment, including different nutrient and oxygen levels, exponential and stationary phases of growth, and in the presence of the stress hormone epinephrine. Fifty micromolar epinephrine did not affect the growth rate or expression of A. suis adhesin genes, but there was a significant growth phase effect for many genes. Most adhesin genes were also differentially expressed during anoxic static growth or aerobic growth, and in this study, all genes were differentially expressed in either exponential or stationary phase. Based on the time*treatment interactions observed in the anoxic study, a model of persistence of A. suis in the host environment in biofilm and planktonic states is proposed. Biofilm dynamics were further studied using wild type and isogenic mutants of the type IVb pilin (D flp1), the OmpA outer membrane protein (DompA), and the fibronectin-binding (DcomE1) genes. Disruption of these adhesin genes affected the early stages of biofilm formation, but in most cases, biofilm formation of the mutant strains was similar to that of the wild type by 24 h of incubation. We postulate that other adhesins may have overlapping functions that can compensate for those of the missing adhesins. 2016 Elsevier B.V. All rights reserved.

Springer eBooks, 1995

The family Pasteurellaceae is comprised of three genera: Haemophilus, Actinobacillus, and Pasteur... more The family Pasteurellaceae is comprised of three genera: Haemophilus, Actinobacillus, and Pasteurella (HAP). These bacteria cause important diseases in humans and animals and are of great medical and economical importance. Recently, the HAP bacteria have been the subject of intensive research in the fields of molecular mechanisms of pathogenicity, immunogenicity, and vaccine development. A considerable amount of work has been done in the molecular analysis of several virulence components including capsule, lipopolysaccharide, outer membrane proteins, and exotoxins. While cloning and expression of genes from the HAP bacteria in established hosts like E. coli K12 strains appears to be easy, very little work has been described on the genetic engineering of the HAP bacteria themselves.

PubMed, Oct 1, 2009

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major cause of economic losses i... more Porcine reproductive and respiratory syndrome virus (PRRSV) is a major cause of economic losses in the swine industry. The disease is widespread worldwide, and so PRRSV-negative pigs are often difficult to find for the study of PRRSV in vivo. To determine if a small animal model could be developed for PRRSV, 3 strains of laboratory rodent were examined for their susceptibility to the virus. No virus replication was detected in BALB/c or SCID (severe combined immunodeficiency) mice after intraperitoneal inoculation. Moderate replication of PRRSV was detected in primary cotton rat lung cell cultures, but no viral replication was detected following intranasal or intraperitoneal inoculation. Following intratracheal inoculation, viral transcripts were detected in the lungs of cotton rats, but only for 1 day. This study indicates that PRRSV replication in common laboratory rodent species is inefficient, and suggests that a rodent model for this virus is not appropriate.

Microbiology resource announcements, Nov 21, 2019

Here, we present data on the complete genome sequences of 11 Staphylococcus sp. isolates (three S... more Here, we present data on the complete genome sequences of 11 Staphylococcus sp. isolates (three S. chromogenes isolates and one isolate each of S. saprophyticus, S. xylosus, S. hominis, S. agnetis, S. caprae, S. aureus, and S. warneri), obtained as part of a mastitis study of buffalo milk (from healthy animals and from those with subclinical mastitis) and milkers' hands.

Fems Microbiology Letters, Jan 17, 2006

BMC Research Notes, 2015

Background: Quantitative real-time PCR is a valuable tool for evaluating bacterial gene expressio... more Background: Quantitative real-time PCR is a valuable tool for evaluating bacterial gene expression. However, in order to make best use of this method, endogenous reference genes for expression data normalisation must first be identified by carefully validating the stability of expression under experimental conditions. Therefore, the objective of this study was to validate eight reference genes of the opportunistic swine pathogen, Actinobacillus suis, grown in aerobic cultures with (Epinephrine) or without (Aerobic) epinephrine in the growth medium and in anoxic static cultures (Anoxic), and sampled during exponential and stationary phases. Results: Using the RefFinder tool, expression data were analysed to determine whether comprehensive stability rankings of selected reference genes varied with experimental design. When comparing Aerobic and Epinephrine cultures by growth phase, pyk and rpoB were both among the most stably expressed genes, but when analysing both growth phases together, only pyk remained in the top three rankings. When comparing Aerobic and Anoxic samples, proS ranked among the most stable genes in exponential and stationary phase data sets as well as in combined rankings. When analysing the Aerobic, Epinephrine, and Anoxic samples together, only gyrA ranked consistently among the top three most stably expressed genes during exponential and stationary growth as well as in combined rankings; the rho gene ranked as least stably expressed gene in this data set. Conclusions: Reference gene stability should be carefully assessed with the design of the experiment in mind. In this study, even the commonly used reference gene 16S rRNA demonstrated large variability in stability depending on the conditions studied and how the data were analysed. As previously suggested, the best approach may be to use a geometric mean of multiple genes to normalise qPCR results. As researchers continue to validate reference genes for various organisms in multiple growth conditions and sampling time points, it may be possible to make informed predictions as to which genes may be most suitable to validate for a given experimental design, but in the meantime, the reference genes used to normalise qPCR data should be selected with caution.

PubMed, Jul 1, 2007

Haemophilus parasuis is an important opportunistic pathogen in swine of high health status, but t... more Haemophilus parasuis is an important opportunistic pathogen in swine of high health status, but to date no proven virulence factors have been described. As virulence factors are known to be regulated during disease, the objective of this study was to identify genes of a virulent serovar 5 strain with altered expression after iron restriction or in the presence of porcine cerebrospinal fluid (CSF), conditions that reflect in vivo growth conditions. Using differential-display reverse-transcriptase-mediated polymerase chain reaction, we found that homologues of genes encoding fructose bisphosphate aldolase (fba), adenylosuccinate synthetase (purA), 2',3'-cyclic nucleotide phosphodiesterase (cpdB), lipoprotein signal peptidase (lspA), pyrophosphate reductase (lytB), superoxide dismutase (sodC), tyrosyl t-RNA synthetase (tyrS), cysteine synthetase (cysK), an unknown protein, and a homologue of a hydrolase of the haloacid dehydrogenase superfamily were upregulated in response to iron restriction. In addition, the purA, cpdB, lspA, lytB, and sodC homologues, cDNAs homologous with a Na+/alanine symporter, fatty acid ligase (fadD), diadenosine tetraphosphatase (apaH), and an unknown protein were upregulated in response to CSF. In screening for the presence of these differentially expressed genes to assess their usefulness as diagnostic markers of high virulence potential, we detected homologues of all of these genes in all of the reference strains of the 15 established serovars. The hydrolase homologue, however, was expressed only in representative H. parasuis strains associated with a high virulence potential, suggesting that this enzyme may play a role in pathogenesis.

PubMed, Sep 1, 2018

The purpose of the study was to identify the serotypes of Streptococcus suis from tonsil swabs in... more The purpose of the study was to identify the serotypes of Streptococcus suis from tonsil swabs in clinically ill and healthy pigs in Ontario using a multiplex polymerase chain reaction (PCR) method. Although 22 different serotypes were identified, most isolates were S. suis-like bacteria or untypable.