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INTRODUCTION Safely increasing organ donation to meet need is a priority. Potential donors may be declined due to perceived blood borne virus (BBV) transmission risk. With hepatitis C (HCV) curative therapy, more potential donors may now be suitable. We sought to describe potential deceased donors with increased BBV transmission risk. METHODS We conducted a cohort study of all potential organ donors referred in New South Wales, Australia, 2010-2018. We compared baseline risk potential donors to potential donors with increased BBV transmission risk, due to history of HIV, HCV or hepatitis B and/or behavioural risk factors. RESULTS There were 624/5749 potential donors (10.9%) perceived to have increased BBV transmission risk. This included 298/5749 (5.2%) with HCV (including HBV co-infections) and 239/5749 (4.2%) with increased risk behaviours (no known BBV). Potential donors with HCV and those with increased risk behaviours were younger and had fewer comorbidities than baseline risk potential donors (p

Background Infections, including common communicable infections such as influenza, frequently cause disease after organ transplantation, although the quantitative extent of infection and disease remains uncertain. Methods A cohort study was conducted to define the burden of notifiable infectious diseases among all solid organ recipients transplanted in New South Wales, Australia, 2000–2015. Data linkage was used to connect transplant registers to hospital admissions, notifiable diseases, and the death register. Standardized incidence ratios (SIRs) were calculated relative to general population notification rates, accounting for age, sex, and calendar year. Infection-related hospitalizations and deaths were identified. Results Among 4858 solid organ recipients followed for 39 183 person-years (PY), there were 792 notifications. Influenza was the most common infection (532 cases; incidence, 1358 [95% CI, 1247–1478] per 100 000 PY), highest within 3 months posttransplant. Next most common was salmonellosis (46 cases; incidence, 117 [95% CI, 87–156] per 100 000 PY), then pertussis (38 cases; incidence, 97 [95% CI, 71–133] per 100 000 PY). Influenza and invasive pneumococcal disease (IPD) showed significant excess cases compared with the general population (influenza SIR, 8.5 [95% CI, 7.8–9.2]; IPD SIR, 9.8 [95% CI, 6.9–13.9]), with high hospitalization rates (47% influenza cases, 68% IPD cases) and some mortality (4 influenza and 1 IPD deaths). By 10 years posttransplant, cumulative incidence of any vaccine-preventable disease was 12%, generally similar by transplanted organ, except higher among lung recipients. Gastrointestinal diseases, tuberculosis, and legionellosis had excess cases among transplant recipients, although there were few sexually transmitted infections and vector-borne diseases. Conclusions There is potential to avoid preventable infections among transplant recipients with improved vaccination programs, health education, and pretransplant donor and recipient screening.

Serological testing for SARS-CoV-2-specific antibodies provides important research and diagnostic information relating to COVID-19 prevalence, incidence and host immune response. A greater understanding of the relationship between functionally neutralising antibodies detected using microneutralisation assays and binding antibodies detected using scalable enzyme immunoassays (EIA) is needed in order to address protective immunity post-infection or vaccination, and assess EIA suitability as a surrogate test for screening of convalescent plasma donors. We assessed whether neutralising antibody titres correlated with signal cut-off ratios in five commercially available EIAs, and one in-house assay based on expressed spike protein targets. Sera from recovered patients or convalescent plasma donors who reported laboratory-confirmed SARS-CoV-2 infection (n = 200), and negative control sera collected prior to the COVID-19 pandemic (n = 100), were assessed in parallel. Performance was assessed by calculating EIA sensitivity and specificity with reference to microneutralisation. Neutralising antibodies were detected in 166 (83%) samples. Compared with this, the most sensitive EIAs were the Cobas Elecsys Anti-SARS-CoV-2 (98%) and Vitros Immunodiagnostic Anti-SARS-CoV-2 (100%), which detect total antibody targeting the N and S1 antigens, respectively. The assay with the best quantitative relationship with microneutralisation was the Euroimmun IgG. These results suggest the marker used (total Ab vs. IgG vs. IgA) and the target antigen are important determinants of assay performance. The strong correlation between microneutralisation and some commercially available assays demonstrates their potential for clinical and research use in assessing protection following infection or vaccination, and use as a surrogate test to assess donor suitability for convalescent plasma donation.

BackgroundSerological testing for SARS-CoV-2 specific antibodies provides important research and diagnostic information relating to COVID-19 prevalence, incidence, and host immune response. A greater understanding of the relationship between functionally neutralising antibodies detected using microneutralisation assays and binding antibodies detected using scalable enzyme immunoassays (EIA) is needed in order to address protective immunity post-infection or vaccination, and assess EIA suitability as a surrogate test for screening of convalescent plasma donors. We assessed whether neutralising antibody titres correlated with signal cut-off ratios in five commercially available EIAs, and one in-house assay based on expressed spike protein targets.MethodsSera from individuals recovered from patients or convalescent plasma donors who reported laboratory-confirmed SARS-CoV-2 infection (n=200), and negative control sera collected prior to the COVID-19 pandemic (n=100) were assessed in parallel. Performance was assessed by calculating EIA sensitivity and specificity with reference to microneutralisation.ResultsNeutralising antibodies were detected in 166 (83%) samples. Compared with this, the most sensitive EIAs were the Cobas Elecsys Anti-SARS-CoV-2 (98%) and Vitros Immunodiagnostic Anti-SARS-CoV-2 (100%), which detect total antibody targeting the N and S1 antigens, respectively. The assay with the best quantitative relationship with microneutralisation was the Euroimmun IgG.ConclusionsThese results suggest the marker used (total Ab vs IgG vs IgA), and the target antigen are important determinants of assay performance. The strong correlation between microneutralisation and some commercially available assays demonstrate their potential for clinical and research use in assessing protection following infection or vaccination, and use as a surrogate test to assess donor suitability for convalescent plasma donation.

Background Blood-borne viral infections can complicate organ transplantation. Systematic monitoring to distinguish donor-transmitted infections from other new infections post transplant is challenging. Administrative health data can be informative. We aimed to quantify post-transplant viral infections, specifically those transmitted by donors and those reactivating or arising new in recipients. Methods We linked transplant registries with administrative health data for all solid organ donor-recipient pairs in New South Wales, Australia, 2000-2015. All new recipient notifications of hepatitis B (HBV), C (HCV), or human immunodeficiency virus (HIV) after transplant were identified. Proven/probable donor transmissions within 12 months of transplant were classified using an international algorithm. Results Of 2120 organ donors, there were 72 with a viral infection (9/72 active, 63/72 past). These 72 donors donated to 173 recipients, of whom 24/173 already had the same infection as their donor, and 149/173 did not, so were at risk of donor transmission. Among those at risk, 3/149 recipients had proven/probable viral transmissions (1 HCV, 2 HBV); none were unrecognized by donation services. There were no deaths from transmissions. There were no donor transmissions from donors without known blood-borne viruses. An additional 68 recipients had new virus notifications, of whom 2/68 died, due to HBV infection. Conclusion This work confirms the safety of organ donation in an Australian cohort, with no unrecognized viral transmissions and most donors with viral infections not transmitting the virus. This may support targeted increases in donation from donors with viral infections. However, other new virus notifications post transplant were substantial and are preventable. Data linkage can enhance current biovigilance systems.

There is increasing demand for organ and tissue donations to cater for a growing waiting list of recipients. Serological screening of donors remains the initial assessment upon which many decisions are made, particularly if donors are found to be seropositive. Multiple different platforms are now available, although the Abbott ARCHITECT platform assays are currently licensed globally for testing of blood collected at less than 15 h post-mortem. Compliance with the specified maximum collection times drastically decreases the number of eligible deceased donors, with ~ 70% more donations available if screened at up to 24 h post mortem. A large scale study on deceased donors was performed where blood was collected between 12 and 25 h post-mortem. A total of 194 cadaveric serological specimens were tested using the Abbott ARCHITECT analyser for Human Immunodeficiency Virus (HIV), Hepatitis B Virus (HBV), Hepatitis C Virus (HCV), Human T Lymphotropic Virus type I/II, and syphilis infection. The specificity, sensitivity, accuracy, reproducibility and influence of storage conditions were assessed for testing with Abbott ARCHITECT platform for HIV antigen/antibody Combo, HCV antibody, HBV surface antigen (HBsAg), HBV core antibody (HBcAb), HTLVI/II antibody (rHTLV-I/II), and Syphilis TP assays. There was no significant difference between testing of sera from living and cadaveric individuals in terms of assay specificity, sensitivity and accuracy. The findings show testing of human serum and plasma specimens collected up to 24 h post-mortem with these assays is acceptable and reflects host status accurately.

Objective To estimate the prevalence and incidence of human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV) among people at increased risk of infection in Australia; to estimate the residual risk of infection among potential solid organ donors in these groups when their antibody and nucleic acid test results are negative. Study design Systematic review and meta-analysis of reports of the incidence and prevalence of HIV, HCV, and HBV in groups at increased risk of infection in Australia. Data sources MEDLINE, government and agency reports, Australasian Society for HIV, Viral Hepatitis and Sexual Health Medicine conference abstracts, the Australian New Zealand Clinical Trial Registry, and National Health and Medical Research Council grants published 1 January 2000 - 14 February 2019; personal communications. Data synthesis Residual risk of HIV infection was highest among men who have sex with men (4.8 [95% CI, 2.7-6.9] per 10 000 antibody-negative persons; 1.5 [95% CI, 0.9-2.2] per 10 000 persons who are both antibody- and nucleic acid-negative). Residual risk of HCV infection was highest among injecting drug users (289 [95% CI, 191-385] per 10 000 antibody-negative persons; 20.9 [95% CI, 13.8-28.0] per 10 000 antibody- and nucleic acid-negative persons). Residual risk for HBV infection was highest among injecting drug users (98.6 [95% CI, 36.4-213] per 10 000 antibody-negative people; 49.4 [95% CI, 18.2-107] per 10 000 persons who were also nucleic acid-negative). Conclusions Absolute risks of window period viral infections are low in people from Australian groups at increased risk but with negative viral test results. Accepting organ donations by people at increased risk of infection but with negative viral test results could be considered as a strategy for expanding the donor pool. Registration International Prospective Register of Systematic Reviews (PROSPERO), CRD42017069820.

Background The most recent documented Australian outbreak of enterovirus A71 (EV-A71) occurred in Sydney from 2012 to 2013. Over a four-month period more than 100 children presented to four paediatric hospitals with encephalitic presentations including fever and myoclonic jerks. The heterogeneous presentations included typical encephalomyelitis, and cardiopulmonary complications. Objectives To characterise the genomes of enterovirus strains circulating during the 2013 Sydney EV-A71 outbreak and determine their phylogeny, phylogeography and association between genome and clinical phenotype. Study design We performed an analysis of enterovirus (EV) positive specimens from children presenting to hospitals in the greater Sydney region of Australia during the 2013 outbreak. We amplified near full-length genomes of EV, and used next generation sequencing technology to sequence the virus. We used phylogenetic/phylogeographic analysis to characterize the outbreak viruses. Results We amplified and sequenced 23/63 (37 %) genomes, and identified the majority (61 %) as EV-A71. The EV-A71 sequences showed high level sequence homology to C4a genogroups of EV-A71 circulating in China and Vietnam during 2012-13. Phylogenetic analysis showed EV-A71 strains associated with more severe symptoms, including encephalitis or cardiopulmonary failure, grouped together more closely than those from patients with hand, foot and mouth disease. Amongst the non-EV-A71 sequences were five other EV subtypes (representing enterovirus subtypes A and B), reflecting the diversity of EV co-circulation within the community. Conclusions This is the first Australian study investigating the near full-length genome of EV strains identified during a known outbreak of EV-A71. EV-A71 sequences were very similar to strains circulating in Asia during the same time period. Whole genome sequencing offers additional information over routine diagnostic testing such as characterisation of emerging recombinant strains and inform vaccine design.

Streptococcus pyogenes (group A Streptococcus (GAS)) causes ∼700 million human infections each year, resulting in over 500,000 deaths. The development of a commercial GAS vaccine is hampered by the occurrence of many unique GAS serotypes, antigenic variation within the same serotype, differences in serotype geographical distribution, and the production of antibodies crossreactive with human tissue that may lead to autoimmune disease. Several independent studies have documented a number of GAS cell wall-associated or secreted metabolic enzymes that contain neither N-terminal leader sequences nor C-terminal cell wall anchors. Here, we applied a proteomic analysis of serotype M1T1 GAS cell wall extracts for the purpose of vaccine development. This approach catalogued several anchorless proteins and identified two protective vaccine candidates, arginine deiminase and trigger factor. These surface-exposed enzymes are expressed across multiple GAS serotypes exhibiting =99% amino acid sequence identity. Vaccine safety concerns are alleviated by the observation that these vaccine candidates lack human homologs, while sera from human populations suffering repeated GAS infections and high levels of autoimmune complications do not recognize these enzymes. Our study demonstrates anchorless cell surface antigens as promising vaccine candidates for the prevention of GAS disease. © Springer-Verlag 2012.

A peptide (J14) containing conformationally restricted epitopes from the M protein of group A streptococcus (GAS) is capable of eliciting protective immune response against GAS infection. However, the protective response may be lost possibly due to its weak secondary-structure when the antigen is fused with other antigens in a recombinant polyepitope vaccine construct. We previously showed that JJo, a conformationally stabilized derivative of dimeric J14, overcomes this problem. We now show that anti JJo antibodies react with diverse GAS isolates found in the Indian sub-continent and that these antibodies are opsonic for GAS. The GAS strains used in this study were isolated from throat and skin swabs from Mumbai, Chennai and Vellore. Sera from mice immunized with recombinant JJo peptide were tested by ELISA, immunofluorescence, flow-cytometry, indirect bactericidal assay and mouse challenge assays to determine specific immunogenicity, opsonic functions and protection against an Indian isolate. We propose that JJo is a robust antigen suitable for inclusion in recombinant multi-epitope vaccines which are potentially affordable option for the pediatric population of developing countries.

The group AStreptococcus(GAS) is an important pathogen that is responsible for a wide range of human diseases. Fibronectin binding proteins (FBPs) play an important role in promoting GAS adherence and invasion of host cells. TheprtF2gene encodes an FBP and is present in approximately 60% of GAS strains. In the present study we examined 51prtF2-positive GAS strains isolated from the Northern Territory of Australia, and here we describe two genotypes ofprtF2which are mutually exclusive. The two genotypes have been identified previously aspfbpandfbaB. We show that these genotypes map to the same chromosomal location within the highly recombinatorial fibronectin-collagen-T antigen (FCT) locus, indicating that they arose from a common ancestor, and in this study these genotypes were designated thepfbptype and thefbaBtype. Phylogenetic analysis of sevenpfbptypes, 14fbaBtypes, and 11prtF2-negative GAS strains by pulsed-field gel electrophoresis (PFGE) produced 32 distinct PFGE patterns. Interpretation of evolution based on the PFGE dendrogram by parsimony suggested that thepfbptype had a recent origin compared to thefbaBtype. A comparison of multiple DNA sequences of thepfbpandfbaBtypes revealed a mosaic pattern for the amino-terminal region of thepfbptypes. ThefbaBtype is generally conserved at the amino terminus but varies in the number of fibronectin binding repeats in the carboxy terminus. Our data also suggest that there is a possible association of thepfbpgenotype withsof(84.2%), while thefbaBgenotype was found in a majority of the GAS strains negative forsof(90.6%), indicating that these twoprtF2subtypes may be under different selective pressures.

Shiga toxin-producing Escherichia coli (STEC) strains possessing genes for enterohemolysin ( ehxA ) and/or intimin ( eae ), referred to here as complex STEC (cSTEC), are more commonly recovered from the feces of humans with hemolytic uremic syndrome and hemorrhagic colitis than STEC strains that do not possess these accessory virulence genes. Ruminants, particularly cattle and sheep, are recognized reservoirs of STEC populations that may contaminate foods destined for human consumption. We isolated cSTEC strains from the feces of longitudinally sampled pasture-fed sheep, lot-fed sheep maintained on diets comprising various combinations of silage and grain, and sheep simultaneously grazing pastures with cattle to explore the diversity of cSTEC serotypes capable of colonizing healthy sheep. A total of 67 cSTEC serotypes were isolated, of which 21 (31.3%), mainly isolated from lambs, have not been reported. Of the total isolations, 58 (86.6%) were different from cSTEC serotypes isolated from a recent study of longitudinally sampled healthy Australian cattle (M. Hornitzky, B. A. Vanselow, K. Walker, K. A. Bettelheim, B. Corney, P. Gill, G. Bailey, and S. P. Djordjevic, Appl. Environ. Microbiol. 68: 6439-6445, 2002). Our data suggest that cSTEC serotypes O5:H − , O75:H8, O91:H − , O123:H − , and O128:H2 are well adapted to colonizing the ovine gastrointestinal tract, since they were the most prevalent serotypes isolated from both pasture-fed and lot-fed sheep. Collectively, our data show that Australian sheep are colonized by diverse cSTEC serotypes that are rarely isolated from healthy Australian cattle.

Unlike Shiga toxin 2 ( stx 2 ) genes, most nucleotide sequences of Shiga toxin 1 ( stx 1 ) genes from Shiga toxin-producing Escherichia coli (STEC), Shigella dysenteriae , and several bacteriophages (H19B, 933J, and H30) are highly conserved. Consequently, there has been little incentive to investigate variants of stx 1 among STEC isolates derived from human or animal sources. However stx 1OX3 , originally identified in an OX3:H8 isolate from a healthy sheep in Germany, differs from other stx 1 subtypes by 43 nucleotides, resulting in changes to 12 amino acid residues, and has been renamed stx 1c . In this study we describe the development of a PCR-restriction fragment length polymorphism (RFLP) assay that distinguishes stx 1c from other stx 1 subtypes. The PCR-RFLP assay was used to study 378 stx 1 -containing STEC isolates. Of these, 207 were isolated from sheep, 104 from cattle, 45 from humans, 11 from meat, 5 from swine, 5 from unknown sources, and 1 from a cattle water trough. Three hundred fifty-five of the 378 isolates (93.9%) also possessed at least one other associated virulence gene ( ehxA , eaeA , and/or stx 2 ); the combination stx 1 , stx 2 , and ehxA was the most common (175 of 355 [49.3%]), and 90 of 355 (25.4%) isolates possessed eaeA . One hundred thirty-six of 207 (65.7%) ovine isolates possessed stx 1c alone and belonged to 41 serotypes. Seventy-one of 136 (52.2%) comprised the common ovine serotypes O5:H − , O128:H2, and O123:H − . Fifty-two of 207 isolates (25.1%) possessed an stx 1 subtype; 27 (51.9%) of these belonged to serotype O91:H − . Nineteen of 207 isolates (9.2%) contained both stx 1c and stx 1 subtypes, and 14 belonged to serotype O75:H8. In marked contrast, 97 of 104 (93.3%) bovine isolates comprising 44 serotypes possessed an stx 1 subtype, 6 isolates possessed stx 1c , and the remaining isolate possessed both stx 1c and stx 1 subtypes. Ten of 11 (91%) isolates cultured from meat in New Zealand possessed stx 1c (serotypes O5:H − , O75:H8/H40, O81:H26, O88:H25, O104:H − /H7, O123:H − /H10, and O128:H2); most of these serotypes are commonly recovered from the feces of healthy sheep. Serotypes containing stx 1 recovered from cattle rarely were the same as those isolated from sheep. Although an stx 1c subtype was never associated with the typical enterohemorrhagic E. coli serogroups O26, O103, O111, O113, and O157, 13 human isolates possessed stx 1c . Of these, six isolates with serotype O128:H2 (from patients with diarrhea), four O5:H − isolates (from patients with hemolytic-uremic syndrome), and three isolates with serotypes O123:H − (diarrhea), OX3:H8 (hemolytic-uremic syndrome), and O81:H6 (unknown health status) represent serotypes that are commonly isolated from sheep.

Shiga toxin 2 (Stx2) has been reported as the main Shiga toxin associated with human disease. In addition, the Stx2 toxin type can have a profound impact on the degree of tissue damage in animal models. We have characterized the stx 2 subtype of 168 Shiga toxin-producing Escherichia coli (STEC) isolates of which 146 were derived from ovine sources (principally feces and meat) and 22 were isolated from humans. The ovine STEC isolates were of serotypes that have been shown to occur commonly in the gastrointestinal tract of healthy sheep. The major stx 2 subtype in the ovine isolates was shown to be stx 2d-Ount (119 of 146 [81.5%]) and was predominantly associated with serotypes O75:H − /H8/H40, O91:H − , O123:H − , O128:H2, and OR:H2. However, 17 of 18 (94.4%) ovine isolates of serotype O5:H − possessed a stx 2d-O111/OX3a subtype. Furthermore, STEC isolates of serotypes commonly found in sheep and recovered from both clinical and nonclinical human infections also contained a stx 2d ( stx 2d-Ount/O111/OX3a ) subtype. These studies suggest that a specific stx 2 subtype(s) associates with serotype and may have important epidemiological implications for tracing sources of E. coli during outbreaks of STEC-associated diseases in humans.

Importance Enterovirus 71 (EV71) causes a spectrum of neurological complications with significant morbidity and mortality. Further understanding of the characteristics of EV71-related neurological disease, factors related to outcome, and potential responsiveness to treatments is important in developing therapeutic guidelines. Objective To further characterize EV71-related neurological disease and neurological outcome in children. Design, Setting, and Participants Prospective 2-hospital (The Sydney Children’s Hospitals Network) inpatient study of 61 children with enterovirus-related neurological disease during a 2013 outbreak of EV71 in Sydney, Australia. The dates of our analysis were January 1, to June 30, 2013. Main Outcomes and Measures Clinical, neuroimaging, laboratory, and pathological characteristics, together with treatment administered and functional motor outcomes, were assessed. Results Among 61 patients, there were 4 precipitous deaths (7%), despite resuscitation at presentation. Among 57 surviving patients, the age range was 0.3 to 5.2 years (median age, 1.5 years), and 36 (63%) were male. Fever (100% [57 of 57]), myoclonic jerks (86% [49 of 57]), ataxia (54% [29 of 54]), and vomiting (54% [29 of 54]) were common initial clinical manifestations. In 57 surviving patients, EV71 neurological disease included encephalomyelitis in 23 (40%), brainstem encephalitis in 20 (35%), encephalitis in 6 (11%), acute flaccid paralysis in 4 (7%), and autonomic dysregulation with pulmonary edema in 4 (7%). Enterovirus RNA was more commonly identified in feces (42 of 44 [95%]), rectal swabs (35 of 37 [95%]), and throat swabs (33 of 39 [85%]) rather than in cerebrospinal fluid (10 of 41 [24%]). Magnetic resonance imaging revealed characteristic increased T2-weighted signal in the dorsal pons and spinal cord. All 4 patients with pulmonary edema (severe disease) demonstrated dorsal brainstem restricted diffusion (odds ratio, 2; 95% CI, 1-4; P = .001). Brainstem or motor dysfunction had resolved in 44 of 57 (77%) at 2 months and in 51 of 57 (90%) at 12 months. Focal paresis was evident in 23 of 57 (40%) at presentation and was the most common persisting clinical and functional problem at 12 months (observed in 5 of 6 patients), with 1 patient also requiring invasive ventilation. Patients initially seen with acute flaccid paralysis or pulmonary edema had significantly greater frequencies of motor dysfunction at follow-up compared with patients initially seen with other syndromes (odds ratio, 15; 95% CI, 3-79; P Conclusions and Relevance Enterovirus 71 may cause serious neurological disease in young patients. The distinct clinicoradiological syndromes, predominantly within the spinal cord and brainstem, enable rapid recognition within evolving outbreaks. Long-term functional neurological morbidity is associated with paresis linked to involvement of gray matter in the brainstem or spinal cord.

Gram-positive streptococci are non-motile, chain-forming bacteria commonly found in the normal oral and bowel flora of warm-blooded animals. Over the past decade, a proteomic approach combining 2-DE and MS has been used to systematically map the cellular, surface-associated and secreted proteins of human pathogenic streptococcal species. The public availability of complete streptococcal genomic sequences and the amalgamation of proteomic, genomic and bioinformatic technologies have recently facilitated the identification of novel streptococcal vaccine candidate antigens and therapeutic agents. The objective of this review is to examine the constituents of the streptococcal cell wall and secreted proteome, the mechanisms of transport of surface and secreted proteins, and describe the current methodologies employed for the identification of novel surface-displayed proteins and potential vaccine antigens.

A common mammalian defense mechanism employed to prevent systemic dissemination of invasive bacteria involves occlusion of local microvasculature and encapsulation of bacteria within fibrin networks. Acquisition of plasmin activity at the bacterial cell surface circumvents this defense mechanism, allowing invasive disease initiation. To facilitate this process, S. pyogenes secretes streptokinase, a plasminogen-activating protein. Streptokinase polymorphism exhibited by S. pyogenes isolates is well characterized. However, the functional differences displayed by these variants and the biological significance of this variation has not been elucidated. Phylogenetic analysis of ska sequences from 28 S. pyogenes isolates revealed 2 main sequence clusters (clusters 1 and 2). All strains secreted streptokinase, as determined by Western blotting, and were capable of acquiring cell surface plasmin activity after incubation in human plasma. Whereas culture supernatants from strains containing cluster 1 ska alleles also displayed soluble plasminogen activation activity, supernatants from strains containing cluster 2 ska alleles did not. Furthermore, plasminogen activation activity in culture supernatants from strains containing cluster 2 ska alleles could only be detected when plasminogen was prebound with fibrinogen. This study indicates that variant streptokinase proteins secreted by S. pyogenes isolates display differing plasminogen activation characteristics and may therefore play distinct roles in disease pathogenesis.

The intimin gene eae , located within the locus of enterocyte effacement pathogenicity island, distinguishes enteropathogenic Escherichia coli (EPEC) and some Shiga toxin-producing E. coli (STEC) strains from all other pathotypes of diarrheagenic E. coli . EPEC is a leading cause of infantile diarrhea in developing countries, and intimin-positive STEC isolates are typically associated with life-threatening diseases such as hemolytic-uremic syndrome and hemorrhagic colitis. Here we describe the development of a PCR-restriction fragment length polymorphism (RFLP) assay that reliably differentiates all 11 known intimin types (α1, α2, β, γ, κ, ε, η, ι, λ, θ, and ζ) and three new intimin genes that show less than 95% nucleotide sequence identity with existing intimin types. We designated these new intimin genes Int-μ, Int-ν, and Int-ξ. The PCR-RFLP assay was used to screen 213 eae -positive E. coli isolates derived from ovine, bovine, and human sources comprising 60 serotypes. Of these, 82 were STEC isolates, 89 were stx -negative ( stx − ) and ehxA -positive ( ehxA + ) isolates, and 42 were stx − and ehxA -negative isolates. Int-β, the most commonly identified eae subtype (82 of 213 [38.5%] isolates), was associated with 21 serotypes, followed by Int-ζ (39 of 213 [18.3%] isolates; 11 serotypes), Int-θ (25 of 213 [11.7%] isolates; 15 serotypes), Int-γ (19 of 213 [8.9%] isolates; 9 serotypes), and Int-ε (21 of 213 [9.9%] isolates; 5 serotypes). Intimin subtypes α1, α2, κ, λ, ξ, μ, ν, and ι were infrequently identified; and Int-η was not detected. Phylogenetic analyses with the Phylip package of programs clustered the intimin subtypes into nine distinct families (α, β-ξ, γ, κ, ε-η-ν, ι-μ, λ, θ, and ζ). Our data confirm that ruminants are an important source of serologically and genetically diverse intimin-containing E. coli strains.