Evaluation of a new dengue 3 controlled human infection model for use in the evaluation of candidate dengue vaccines.

All four serotypes of dengue virus (DENV) cause the full spectrum of disease. Therefore, vaccines must protect against all serotypes. To evaluate candidate vaccines, a human challenge model of dengue serotype 3 (rDEN30Δ30) was developed. All challenge virus recipients safely met the primary endpoint of viremia and secondary endpoints of rash and seroconversion to DENV-3.

Caught in the act: in vivo development of macrolide resistance to Campylobacter jejuni infection.

We report the first instance of macrolide resistance developing in vivo following appropriate antibiotic use in a healthy volunteer as a part of a controlled human infection with Campylobacter jejuni. In vivo development of macrolide resistance may be an important contributor to antibiotic resistance in C. jejuni.

Deficient serum mannose-binding lectin levels and MBL2 polymorphisms increase the risk of single and recurrent Cryptosporidium infections in young children.

Mannose-binding lectin (MBL) is an evolutionarily conserved protein that functions in human innate immunity by binding to microbial surfaces and promoting opsonophagocytosis. MBL has been shown to bind to Cryptosporidium sporozoites, and earlier work has suggested that the protective role of MBL may be most important in childhood. We evaluated the association between polymorphisms in the MBL gene (MBL2), serum MBL deficiency, and infection with Cryptosporidium, Entamoeba histolytica, and Giardia intestinalis in children. A large, prospective cohort of Bangladeshi preschool children was followed up for >3 years. Clinical outcomes, serum MBL levels, and MBL2 polymorphisms and haplotypes were determined. Statistically significant associations with E. histolytica and G. intestinalis were not found. Serum MBL deficiency, polymorphisms in the -221 promoter region, and the YO/XA MBL2 haplotype were strongly associated with Cryptosporidium infections, particularly recurrent infection. Children with multiple infections with Cryptosporidium were more likely to be MBL deficient (odds ratio [OR], 10.45), carry the -221 promoter variant (OR, 4.02), and have the YO/XA haplotype (OR, 4.91). We have identified a potentially important component of the human innate immune response to Cryptosporidum infection. Further work is needed to evaluate the mechanism of protection of MBL in Cryptosporidium infection.

Childhood cryptosporidiosis is associated with a persistent systemic inflammatory response.

Cryptosporidiosis in young children prompts local inflammation in the intestinal tract. We studied a cohort of young children with cryptosporidiosis to determine whether systemic inflammatory responses occur and, if so, to evaluate whether inflammation persists after infection. Cryptosporidiosis was associated with increased levels of interleukin-8 and tumor necrosis factor- alpha systemically, which persisted at 6 months after enrollment. The level of intestinal tumor necrosis factor- alpha was elevated at enrollment, but elevated levels did not persist. Worsening of malnutrition, particularly stunting, was observed after infection. The association of cryptosporidiosis, inflammation, and stunting in children with cryptosporidiosis warrants further evaluation.

Serum mannose-binding lectin deficiency is associated with cryptosporidiosis in young Haitian children.

BACKGROUND: Mannose-binding lectin (MBL) is a component of the innate immune response and binds microbial surfaces through carbohydrate recognition domains. MBL deficiency may contribute to susceptibility to a variety of infectious diseases, particularly in young children. MBL binds to the Cryptosporidium sporozoite and may be important in resistance to cryptosporidiosis. METHODS: We studied the association of serum MBL levels and cryptosporidiosis in a case-control study of young Haitian children with cryptosporidiosis versus children who were control subjects. RESULTS: Ninety-nine children were enrolled, as follows: 49 children with cryptosporidiosis, 41 healthy controls, and 9 children with diarrhea from other causes. Case children were more malnourished than controls, and 49% had persistent or chronic diarrhea. At enrollment, mean serum MBL levels were markedly lower in children with cryptosporidiosis (P = .002), as was the number of children with an MBL deficiency of < or = 70 ng/mL (P = .005). In multivariate analysis, the association of cryptosporidiosis and MBL deficiency persisted (P = .002; adjusted odds ratio, 22.4), as did the association of cryptosporidiosis with general malnutrition. The subset of children with cryptosporidiosis and MBL deficiency were more likely to be male (P = .025). CONCLUSIONS: MBL may be an important component of innate immune protection against Cryptosporidium infection in young children. Additional studies are necessary to determine whether MBL intestinal losses, deficient epithelial expression, and/or genetic polymorphisms in the MBL gene contribute to MBL deficiency in cryptosporidiosis and other enteric infections in young children.

Pseudomesotheliomatous adenocarcinoma of the lung in a patient with HIV infection.

Clinical and pathologic findings are presented of the first reported case in the English-language medical literature of pseudomesotheliomatous adenocarcinoma (PMA) occurring in an HIV-infected patient. PMA is an uncommon variant of peripheral lung cancer which typically occurs in elderly male patients. It mimics a malignant mesothelioma in terms of its clinical presentation and gross and microscopic appearance. The occurrence of this rare tumor in a young HIV-infected patient suggests some association between HIV infection and the development of PMA.

In a randomized, double-blinded, placebo-controlled trial, the single oral dose typhoid vaccine, M01ZH09, is safe and immunogenic at doses up to 1.7 x 10(10) colony-forming units.

M01ZH09, S. Typhi (Ty2 Delta aroC Delta ssaV) ZH9, is a single oral dose typhoid vaccine with independently attenuating deletions. A phase II randomized, double-blind, placebo-controlled, dose-escalating trial evaluated the safety and immunogenicity of M01ZH09 to 1.7 x 10(10) colony-forming units (CFU). 187 Healthy adults received vaccine or placebo in four cohorts. Serologic responses and IgA ELISPOT were measured. At all doses, the vaccine was well tolerated and without bacteremias. One subject had a transient low-grade fever. 62.2-86.1% of subjects seroconverted S. Typhi-specific LPS IgG and 83.3-97.4% IgA; 92.1% had a positive S. Typhi LPS ELISPOT. M01ZH09 is safe and immunogenic up to 1.7 x 10(10)CFU. Efficacy testing of this single-dose oral typhoid vaccine is needed.

Evaluation of Salmonella enterica serovar Typhi (Ty2 aroC-ssaV-) M01ZH09, with a defined mutation in the Salmonella pathogenicity island 2, as a live, oral typhoid vaccine in human volunteers.

Salmonella enterica serovar Typhi strains with mutations in the Salmonella pathogenicity island-2 (SPI-2) may represent an effective strategy for human vaccine development, and a vectoring system for heterologous antigens. S. Typhi (Ty2 aroC-ssaV-) M01ZH09 is an attenuated, live, oral typhoid vaccine harboring defined deletion mutations in ssaV, which encodes an integral component in the SPI-2 type III secretion system (TTSS), as well as a mutation in an aromatic biosynthetic pathway needed for bacterial growth in vivo (aroC). SPI-2 mutant vaccines have yet to be evaluated in a large, randomized human trial. A simplified or single-oral dose oral typhoid vaccine using the SPI-2 strategy would offer significant advantages over the currently licensed typhoid vaccines. We performed a double-blinded, placebo-controlled, dose-escalating clinical trial in 60 healthy adult volunteers to determine the tolerability and immunogenicity of a single dose of M01ZH09. Three groups of 20 healthy adult volunteers were enrolled; 16 in each group received a single oral dose of the freeze-dried vaccine at 5 x 10(7), 5 x 10(8) or 5 x 10(9)CFU in a bicarbonate buffer. Four volunteers in each cohort received placebo in the same buffer. Adverse events were infrequent and not statistically different between vaccine and placebo recipients, although two subjects in the mid-range dose and three subjects in the highest dose had temperature measurements >37.5 degrees C. No blood or urine cultures were positive for M01ZH09, and fecal shedding was brief. The immune response was dose-related; the highest vaccine dose (5 x 10(9)CFU) was the most immunogenic. All tested subjects receiving the highest dose had a significant ASC response (mean 118 spots/10(6) cells). A >or=4-fold increase in antibody titer for S. Typhi LPS or flagellin was detected in 75% of volunteers in the highest-dose cohort by day 28. The SPI-2 mutant vaccine, M01ZH09, is a promising typhoid vaccine candidate and deserves further study as a vectoring system for heterologous vaccine antigens.

Comparison of the antibodies in lymphocyte supernatant and antibody-secreting cell assays for measuring intestinal mucosal immune response to a novel oral typhoid vaccine (M01ZH09).

Antibody-secreting cell (ASC) and antibodies in lymphocyte supernatant (ALS) assays are used to assess intestinal mucosal responses to enteric infections and vaccines. The ALS assay, performed on cell supernatants, may represent a convenient alternative to the more established ASC assay. The two methods, measuring immunoglobulin A to Salmonella enterica serovar Typhi lipopolysaccharide, were compared in volunteers vaccinated with a live-attenuated typhoid vaccine M01ZH09. The specificity of the ALS assay compared to the ASC assay was excellent (100%), as was sensitivity (82%). The ALS assay was less sensitive than the ASC assay at

An outbreak of vancomycin-dependent Enterococcus faecium in a bone marrow transplant unit.

Outbreaks of vancomycin-resistant enterococci (VRE) are well described. The presence of mutants of VRE, such as vancomycin-dependent enterococci (VDE), in individual patients has been documented, but their potential to spread nosocomially has not been known. We present the first cluster of patients who acquired VDE nosocomially. Five bone marrow transplantation patients were infected or colonized by a genotypically indistinguishable multiantibiotic-resistant strain of Enterococcus faecium. Vancomycin dependence in 3 of the 5 isolates was demonstrated. All cluster patients had received protracted prophylactic treatment with vancomycin (mean, 22.6 days), and specimens from >/=2 body sites were repeatedly culture-positive for the outbreak strain. The outbreak was controlled with aggressive infection control strategies, and prophylactic antibiotic policies were revised. Awareness of the potential for nosocomial spread of multiantibiotic-resistant VDE is vital for the care of immunocompromised patients, especially those receiving prophylactic antibiotics.