Sofie Livio

Shigella Isolates From the Global Enteric Multicenter Study Inform Vaccine Development

Shigella case isolates from the Global Enteric Multicenter Study were serotyped to guide vaccine development. A quadrivalent vaccine that includes O antigens from S. sonnei, S. flexneri 2a, S. flexneri 3a, and S. flexneri 6 should provide broad protection.

Identification by PCR of Non-typhoidal Salmonella enterica Serovars Associated with Invasive Infections among Febrile Patients in Mali

Background In sub-Saharan Africa, non-typhoidal Salmonella (NTS) are emerging as a prominent cause of invasive disease (bacteremia and focal infections such as meningitis) in infants and young children. Importantly, including data from Mali, three serovars, Salmonella enterica serovar Typhimurium, Salmonella Enteritidis and Salmonella Dublin, account for the majority of non-typhoidal Salmonella isolated from these patients. Methods We have extended a previously developed series of polymerase chain reactions (PCRs) based on O serogrouping and H typing to identify Salmonella Typhimurium and variants (mostly I 4,[5],12:i:-), Salmonella Enteritidis and Salmonella Dublin. We also designed primers to detect Salmonella Stanleyville, a serovar found in West Africa. Another PCR was used to differentiate diphasic Salmonella Typhimurium and monophasic Salmonella Typhimurium from other O serogroup B, H:i serovars. We used these PCRs to blind-test 327 Salmonella serogroup B and D isolates that were obtained from the blood cultures of febrile patients in Bamako, Mali. Principal Findings We have shown that when used in conjunction with our previously described O-serogrouping PCR, our PCRs are 100% sensitive and specific in identifying Salmonella Typhimurium and variants, Salmonella Enteritidis, Salmonella Dublin and Salmonella Stanleyville. When we attempted to differentiate 171 Salmonella Typhimurium (I 4,[ 5],12:i:1,2) strains from 52 monophasic Salmonella Typhimurium (I 4,[5],12:i:-) strains, we were able to correctly identify 170 of the Salmonella Typhimurium and 51 of the Salmonella I 4,[5],12:i:- strains. Conclusion We have described a simple yet effective PCR method to support surveillance of the incidence of invasive disease caused by NTS in developing countries.

PCR Method To Identify Salmonella enterica Serovars Typhi, Paratyphi A, and Paratyphi B among Salmonella Isolates from the Blood of Patients with Clinical Enteric Fever

ABSTRACT PCR methodology was developed to identify Salmonella enterica serovars Typhi, Paratyphi A, and Paratyphi B. One multiplex PCR identifies serogroup D, A, and B and Vi-positive strains; another confirms flagellar antigen “d,” “a,” or “b.” Blinded testing of 664 Malian and Chilean Salmonella blood isolates demonstrated 100% sensitivity and specificity.

Immune Responses to an Oral Typhoid Vaccine Strain That Is Modified to Constitutively Express Vi Capsular Polysaccharide

Protection against typhoid fever might be best achieved by a vaccine that stimulates IgG antibody to Vi capsular polysaccharide (Vi) in serum, IgG antibody to O antigen in serum, and cell-mediated immune responses. Live typhoid vaccines have not elicited anti-Vi antibody, presumably because Vi expression is highly regulated. CVD 909 is an oral attenuated typhoid vaccine candidate that is engineered to constitutively express Vi. In the present study, CVD 909, at doses of 10(6-9) cfu, was orally administered to 32 healthy adults, and immune responses were measured. Although many of the volunteers generated antibody-secreting cell responses to Vi, only 2 of the 32 volunteers generated anti-Vi IgG antibody in serum.

Safety and immunogenicity of CVD 1208S, a live, oral DeltaguaBA Deltasen Deltaset Shigella flexneri 2a vaccine grown on animal-free media.

A previous Phase 1 trial demonstrated that Shigella flexneri 2a deleted in guaBA, sen and set (strain CVD 1208) is well-tolerated and immunogenic after a single oral dose of 108 or 109 CFU. To facilitate further clinical development, the strain was reconstructed using animal-free media to conform to regulatory guidelines, and designated CVD1208S. Healthy inpatient volunteers were randomized (double-blind) to receive a single oral dose of either CVD 1208S (108 [n = 7] or 109 [n = 7] CFU) or placebo (n = 2). Both vaccine dosage levels were generally well-tolerated. Anti-lipopolysaccharide responses, measured as IgA antibody secreting cells, serum IgG, or fecal IgA levels, occurred in 7 (100%), 3 (43%) and 2 (29%) subjects, respectively, following inoculation with 109 CFU. Interferon gamma production in response to Shigella antigens was observed in 1 of 4 (25%) and 4 of 7 (57%) subjects, respectively, following inoculation with 108 and 109 CFU. We conclude that CVD 1208S retains a favorable safety and immunogenicity profile after reconstruction on animal-free media, comparable to that seen with CVD 1208, which was constructed on media containing animal products, and shows promise as a live, oral Shigella vaccine.

The Burden of Cryptosporidium Diarrheal Disease among Children < 24 Months of Age in Moderate/High Mortality Regions of Sub-Saharan Africa and South Asia, Utilizing Data from the Global Enteric Multicenter Study (GEMS)

Background The importance of Cryptosporidium as a pediatric enteropathogen in developing countries is recognized. Methods Data from the Global Enteric Multicenter Study (GEMS), a 3-year, 7-site, case-control study of moderate-to-severe diarrhea (MSD) and GEMS-1A (1-year study of MSD and less-severe diarrhea [LSD]) were analyzed. Stools from 12,110 MSD and 3,174 LSD cases among children aged <60 months and from 21,527 randomly-selected controls matched by age, sex and community were immunoassay-tested for Cryptosporidium. Species of a subset of Cryptosporidium-positive specimens were identified by PCR; GP60 sequencing identified anthroponotic C. parvum. Combined annual Cryptosporidium-attributable diarrhea incidences among children aged <24 months for African and Asian GEMS sites were extrapolated to sub-Saharan Africa and South Asian regions to estimate region-wide MSD and LSD burdens. Attributable and excess mortality due to Cryptosporidium diarrhea were estimated. Findings Cryptosporidium was significantly associated with MSD and LSD below age 24 months. Among Cryptosporidium-positive MSD cases, C. hominis was detected in 77.8% (95% CI, 73.0%-81.9%) and C. parvum in 9.9% (95% CI, 7.1%-13.6%); 92% of C. parvum tested were anthroponotic genotypes. Annual Cryptosporidium-attributable MSD incidence was 3.48 (95% CI, 2.27–4.67) and 3.18 (95% CI, 1.85–4.52) per 100 child-years in African and Asian infants, respectively, and 1.41 (95% CI, 0.73–2.08) and 1.36 (95% CI, 0.66–2.05) per 100 child-years in toddlers. Corresponding Cryptosporidium-attributable LSD incidences per 100 child-years were 2.52 (95% CI, 0.33–5.01) and 4.88 (95% CI, 0.82–8.92) in infants and 4.04 (95% CI, 0.56–7.51) and 4.71 (95% CI, 0.24–9.18) in toddlers. We estimate 2.9 and 4.7 million Cryptosporidium-attributable cases annually in children aged <24 months in the sub-Saharan Africa and India/Pakistan/Bangladesh/Nepal/Afghanistan regions, respectively, and ~202,000 Cryptosporidium-attributable deaths (regions combined). ~59,000 excess deaths occurred among Cryptosporidium-attributable diarrhea cases over expected if cases had been Cryptosporidium-negative. Conclusions The enormous African/Asian Cryptosporidium disease burden warrants investments to develop vaccines, diagnostics and therapies.

Clinical and Microbiological Responses of Volunteers to Combined Intranasal and Oral Inoculation with a Streptococcus gordonii Carrier Strain Intended for Future Use as a Group A Streptococcus Vaccine

ABSTRACT Streptococcus gordonii shows promise as a live mucosal vaccine vector for immunization against respiratory pathogens. In preparation for clinical trials to evaluate S. gordonii engineered to express group A streptococcal M protein antigens, we characterized the responses of 150 healthy volunteers to combined nasal and oral inoculation with approximately 1.5 × 109 CFU of SP204(1-1), an S. gordonii strain not bearing vaccine antigens. SP204(1-1) was selected for resistance to streptomycin and 5-fluoro-2-deoxyuridine to distinguish it from indigenous flora. In two antibiotic treatment studies, we performed serial culturing of nose, mouth, and saliva samples from 120 subjects treated with azithromycin beginning 5 days after inoculation to determine whether SP204(1-1) could be rapidly eliminated should safety concerns arise. A natural history study was performed to assess the time until spontaneous eradication in the remaining 30 subjects, who did not receive the antibiotic and who were monitored with repeated culturing for 14 weeks after inoculation. SP204(1-1) was generally well tolerated. Symptoms reported most often within 5 days of inoculation were nasal congestion (36%), headache (30%), and sore throat (19%). The strain was detected by culturing in 98% of subjects. A single dose of azithromycin eliminated colonization in 95% of subjects; all subjects receiving a 5-day course of an antibiotic showed clearance by day 11. Without the antibiotic, 82% of subjects showed spontaneous eradication of the implanted strain within 7 days, and all showed clearance by 35 days. The results of these clinical trials provide encouragement that the use of S. gordonii as a live mucosal vaccine vector is a feasible strategy.

Safety and Immunogenicity of Single-Dose Live Oral Cholera Vaccine Strain CVD 103-HgR, Prepared from New Master and Working Cell Banks

ABSTRACT Currently, no cholera vaccine is available for persons traveling from the United States to areas of high cholera transmission and who for reasons of occupation or host factors are at increased risk for development of the disease. A single-dose oral cholera vaccine with a rapid onset of protection would be particularly useful for such travelers and might also be an adjunct control measure for cholera outbreaks. The attenuated Vibrio cholerae O1 vaccine strain CVD 103-HgR harbors a 94% deletion of the cholera toxin A subunit gene (ctxA) and has a mercury resistance gene inserted in the gene encoding hemolysin A. We undertook a phase I randomized placebo-controlled two-site trial to assess the safety and immunogenicity of a preliminary formulation of CVD 103-HgR prepared from new master and working cell banks. Healthy young adults were randomized (5:1 vaccinees to placebo recipients) to receive a single oral dose of ∼4.4 × 108 CFU of vaccine or a placebo. Blood serum vibriocidal and cholera toxin-specific IgG antibodies were measured before and 10, 14, and 28 days following vaccination or placebo. Excretion of the vaccine strain in the stool was assessed during the first week postvaccination. A total of 66 subjects were enrolled, comprising 55 vaccinees and 11 placebo recipients. The vaccine was well tolerated. The overall vibriocidal and anti-cholera toxin seroconversion rates were 89% and 57%, respectively. CVD 103-HgR is undergoing renewed manufacture for licensure in the United States under the auspices of PaxVax. Our data mimic those from previous commercial formulations that elicited vibriocidal antibody seroconversion (a correlate of protection) in ∼90% of vaccinees. (This study has been registered at ClinicalTrials.gov under registration no. NCT01585181.)

Lack of prophylactic efficacy of an enteric-coated bovine hyperimmune milk product against enterotoxigenic Escherichia coli challenge administered during a standard meal.

Orally administered bovine immunoglobulins with specific activity against colonization factors of enterotoxigenic Escherichia coli (ETEC) could provide passive protection against ETEC challenge in volunteers. Twenty healthy adult volunteers ingested either a placebo or a partially enteric-coated preparation of bovine immunoglobulins with activity against the colonization factor antigens CFA/I, CS3, and CS6 and then were challenged with ETEC strain E24377A (CS1+, CS3+) administered with a standard meal. There was no difference in the incidence or severity of diarrhea among the 10 volunteers who received the bovine immunoglobulins and the 10 who received placebo. Either the specificity or titer of anti-colonization factor antibodies or the formulation of antibodies in this product was not adequate to provide passive protection against ETEC challenge.

Escherichia coli O157:H7 Infection in Dutch Belted and New Zealand White Rabbits

Wun-Ju Shieh graduated from Taipei Medical University in 1979. He completed an internal medicine residency and infectious disease subspecialty training in 1986. He received a Master of Public Health from Harvard University in 1987, followed by a Ph.D. in Microbiology & Immunology from Vanderbilt University in 1992. Afterwards, he completed a combined anatomical and clinical pathology residency training at Vanderbilt University Medical Center and an infectious disease pathology fellowship at CDC. He has been working as a medical officer and pathologist at CDC since 1995. He has participated many outbreak investigations, and has published more than 120 papers in peer-review journals. The role of pathology in diagnosis of emerging viral zoonosesChi-Chao Chan earned her M.D. from Johns Hopkins University and ophthalmology residency from Stanford University School of Medicine. She has completed two post-doctoral fellowships: ophthalmic pathology at Wilmer Institute, Johns Hopkins and clinical ocular immunology at National Eye Institute, National Institutes of Health. She is the Chief of Immunopathology Section, Laboratory of Immunology and Head of Histopathology Core, National Eye Institute, the federal government medical research institute in the US. She has published 582 papers in peer-reviewed journals, 51 book chapters, and one textbook. She also serves as an editorial board member for 16 medical journals. Diagnosis of primary vitreoretinal lymphoma, a subtype of primary CNS lymphomaEnterohemorrhagic Escherichia coli (EHEC) produce one or more types of Shiga toxins and are foodborne causes of bloody diarrhea. The prototype EHEC strain, Escherichia coli O157:H7, is responsible for both sporadic cases and serious outbreaks worldwide. Infection with E. coli that produce Shiga toxins may lead to diarrhea, hemorrhagic colitis, or (less frequently) hemolytic uremic syndrome, which can cause acute kidney failure. The exact mechanism by which EHEC evokes intestinal and renal disease has not yet been determined. The development of a readily reproducible animal oral-infection model with which to evaluate the full pathogenic potential of E. coli O157:H7 and assess the efficacy of therapeutics and vaccines remains a research priority. Dutch belted (DB) rabbits are reported to be susceptible to both natural and experimental EHEC-induced disease, and New Zealand white (NZW) rabbits are a model for the intestinal manifestations of EHEC infection. In the current study, we compared the pathology caused by E. coli O157:H7 infection in DB and NZW rabbits. Both breeds of rabbits developed clinical signs of disease and intestinal lesions after experimental infection. In addition, one of the infected DB rabbits developed renal lesions. Our findings provide evidence that both breeds are susceptible to E. coli O157:H7 infection and that both may be useful models for investigating EHEC infections of humans.Lymphocytes play key roles in the chronic inflammation critical for T2D pathogenesis. We have shown T2D patients have an elevated ratio of pro- to anti-inflammatory T cells, and B cells that produce a pro-inflammatory cytokine profile. Thus lymphocytes promote T2D-associated inflammation. Numerous studies implicate the pro-inflammatory CD4+ T cell balance in T2D pathogenesis, but mechanisms that underlie elevated CD4+ T cell inflammation are poorly understood. We explored the possibility that the T2D-associated changes we identified in B cell function regulate T cell inflammation. We show that B cells control the T2D-associated increase in Th17-mediated inflammation in T2D patients and in obese/insulin resistant mice. Surprisingly, the disease-associated ability of B cells to regulate T cell function is contact-dependent, despite evidence that B cell cytokines hyper-secreted in T2D patients activate T cells. In contrast, elevated activation of Th1 cytokines is B cell-independent. We conclude that both T cell-intrinsic and T cell-extrinsic (B cell-dependent) changes regulate T cell inflammation in T2D. These data indicate that B cell depletion may partially curb T2D-associated T cell inflammation, and thus disease pathogenesis; however, combinatorial treatments aimed at multiple inflammatory axes may be required for favorable clinical outcomes.