The endemic Helicobacter pylori population in Southern Vietnam has both South East Asian and European origins

Background The burden of Helicobacter pylori-induced gastric cancer varies based on predominant H. pylori population in various geographical regions. Vietnam is a high H. pylori burden country with the highest age-standardized incidence rate of gastric cancer (16.3 cases/100,000 for both sexes) in Southeast Asia, despite this data on the H. pylori population is scanty. We examined the global context of the endemic H. pylori population in Vietnam and present a contextual and comparative genomics analysis of 83 H. pylori isolates from patients in Vietnam. Results There are at least two major H. pylori populations are circulating in symptomatic Vietnamese patients. The majority of the isolates (~ 80%, 66/83) belong to the hspEastAsia and the remaining belong to hpEurope population (~ 20%, 17/83). In total, 66 isolates (66/83) were cagA positive, 64 were hspEastAsia isolates and two were hpEurope isolates. Examination of the second repeat region revealed that most of the cagA genes were ABD type (63/66; 61 were hspEastAsia isolates and two were hpEurope isolates). The remaining three isolates (all from hspEastAsia isolates) were ABC or ABCC types. We also detected that 4.5% (3/66) cagA gene from hspEastAsia isolates contained EPIYA-like sequences, ESIYA at EPIYA-B segments. Analysis of the vacA allelic type revealed 98.8% (82/83) and 41% (34/83) of the strains harboured the s1 and m1 allelic variant, respectively; 34/83 carried both s1m1 alleles. The most frequent genotypes among the cagA positive isolates were vacA s1m1/cagA + and vacA s1m2/cagA + , accounting for 51.5% (34/66) and 48.5% (32/66) of the isolates, respectively. Conclusions There are two predominant lineages of H. pylori circulating in Vietnam; most of the isolates belong to the hspEastAsia population. The hpEurope population is further divided into two smaller clusters.

Helicobacter pylori-induced TLR9 Activation and Injury are Associated with the Virulence-Associated Adhesin HopQ

Helicobacter pylori is the strongest risk factor for gastric adenocarcinoma. The H. pylori cancer-associated cag pathogenicity island (cag-PAI) encodes a type IV secretion system (T4SS) which translocates microbial DNA and activates TLR9; however, most cag-PAI + infected persons do not develop cancer and cag-PAI-independent regulators of pathogenesis, including strain-specific adhesins, remain understudied. We defined the relationships between H. pylori HopQ adhesin allelic type, gastric injury, and TLR9 activation. Type I hopQ alleles were significantly associated with magnitude of injury, cag-T4SS function, and TLR9 activation. Genetic deletion of hopQ significantly decreased H. pylori-induced TLR9 activation, implicating this adhesin in H. pylori-mediated disease.

Detection and Prevalence of Listeria in U.S. Produce Packinghouses and Fresh-Cut Facilities

ABSTRACT Listeria monocytogenes (LM) contamination of produce can often be traced back to the environment of packinghouses and fresh-cut facilities. Because there is limited information on the detection, prevalence, and distribution of this pathogen in produce operations, environmental “routine sampling” plans for LM and other Listeria spp. were developed and implemented in three packinghouses and five fresh-cut facilities in the United States. For routine sampling, a total of 2,014 sponge samples were collected over six to eight separate samplings per operation, performed over 1 year; vector and preproduction samples (n = 156) were also collected as needed to follow up on positive findings. In addition, a single “validation sampling” visit by an outside expert was used to evaluate the routine sampling. Among the 2,014 routine sponge samples collected, 35 and 30 were positive for LM and Listeria species other than LM (LS), respectively. LM prevalence varied from 0.8 to 5.8% for packinghouses and <0.4 to 1.6% for fresh-cut facilities. Among the 394 validation sponge samples, 23 and 13 were positive for LM and LS, respectively. Validation sampling found statistically significantly higher LM prevalence compared with routine sampling for three of eight operations. For all samples collected, up to eight isolates per sample were characterized by sequencing of sigB, which allowed for classification into sigB allelic types. Among the 97 samples with more than one Listeria isolate characterized, 28 had more than one sigB allelic type present, including 18 sponges that were positive for LM and another Listeria species and 13 sponges that were positive for more than one LM subtype. This indicates that collection of multiple isolates is necessary to capture Listeria diversity present in produce operations. Additionally, 17 of 77 sponges that were positive for LM were positive at only one enrichment time (i.e., 24 or 48 h), indicating that LM testing after two different enrichment times provides enhanced sensitivity. HIGHLIGHTS

Prevalence, Persistence, and Diversity of Listeria monocytogenes and Listeria Species in Produce Packinghouses in Three U.S. States

ABSTRACT Listeria monocytogenes has emerged as a food safety concern for several produce commodities. Although L. monocytogenes contamination can occur throughout the supply chain, contamination from the packinghouse environment represents a particular challenge and has been linked to outbreaks and recalls. This study aimed to investigate the prevalence, persistence, and diversity of L. monocytogenes and other species of Listeria in produce packinghouses. A longitudinal study was performed in 11 packinghouses (whose commodities included microgreen, peach, apple, tomato, broccoli, cauliflower, and cucumber) in three U.S. states. In each packinghouse, 34 to 47 sites representing zones 2 to 4 were selected and swabbed. Packinghouses were visited four times over the packing season, and samples were tested for Listeria by following the U.S. Food and Drug Administration's Bacteriological Analytical Manual methods. Presumptive Listeria-positive isolates were confirmed by PCR. Species and allelic type (AT) were identified by sigB sequencing for up to eight isolates per sample. Among 1,588 samples tested, 50 (3.2%), 42 (2.7%), and 10 (0.6%) samples were positive for L. monocytogenes only, Listeria spp. (excluding L. monocytogenes) only, and both L. monocytogenes and Listeria spp., respectively. Five species of Listeria (L. monocytogenes, L. innocua, L. seeligeri, L. welshimeri, and L. marthii) were identified, and L. monocytogenes was the most prevalent species. The 102 Listeria-positive samples yielded 128 representative isolates (i.e., defined as isolates from a given sample with a different AT). Approximately 21% (21 of 102) of the Listeria-positive samples contained two or more ATs. A high AT diversity (0.95 Simpson's diversity index) was observed among Listeria isolates. There were three cases of L. monocytogenes or Listeria spp. repeated isolation (site testing positive at least twice) based on AT data. Data from this study also support the importance of drain and moisture management, because Listeria were most prevalent in samples collected from drain, cold storage, and wet nonfood contact surface sites. HIGHLIGHTS

Genetic diversity of Plasmodium falciparum and genetic profile after artemisinin-based combination therapy (ACTs) deployment in Cameroon for the management of uncomplicated malaria in Children

Background Plasmodium falciparum is the number one cause of malaria morbidity and mortality. Several methods of intervention have been deployed in Cameroon with an attempt to reduce malaria transmission. But evaluation methods mostly based on microscopy and immunology have proven to be cumbersome and expensive. This study aimed at analyzing the genetic diversity of P.falciparum and the impact of ACTs deployment on MOI Method 350 clinical isolates were collected between 2012 and 2013 and, three P. falciparum loci namely, msp-1(block2), msp-2 (block3), and glurp, (region II) characterized by nested PCR and DNA sequencing. Results From this study, a total of 16 different pfmsp1 were identified, including K1, MAD20 and RO33 allelic families. The K1 and MAD20 were the predominant polymorphic allelic types at the msp-1 gene, whereas alleles belonging to 3D7/IC were more frequent at the msp-2 gene. A peculiarity of this study is that RO33 revealed a monomorphic pattern among the msp-1 allelic type. Msp-1 and msp-2 revealed considerably greater parasite diversity than glurp. A total of 27 different msp-2 genotypes were recorded of which 15 belonged to the 3D7-type and 12 to the FC27 allelic families. Alignment of peptides encoded by pfmsp1 and Pfmsp2 reveals that K1 polymorphism had the highest similarity in the P.fmsp1 and Pfmsp2 clade followed by MAD20 with 93% to 100% homology. Indicating that P. falciparum isolates from Cameroon present high identity with allelic sequences from other areas in Africa, suggesting that vaccine developed with k1 and MAD20 of Pfmsp1 allelic variant could be protective for Africa children. The MOI ranged from 2.51 for msp1 to 3.82 for msp2. The overall heterozygosity ranged from 0.55 for msp-1 to 0.96 for msp-2 consistent with the genetic pattern observed in hyperendemic areas. Conclusion The present study reveals that isolates from South West Region of Cameroon are mainly polyclonal with high MOI and highly diverse in respect to both msp-1 and msp-2 despite ACTs deployment aiming at reducing malaria transmission. This study lays emphasis on the use of MOI and genotyping of both msp-1 and msp-2 in the evaluation of malaria control intervention in malaria endemics countries.

Gastric lymphoma: association withHelicobacter pyloriouter membrane protein Q (HopQ) and cytotoxic-pathogenicity activity island (CPAI) genes

SUMMARYB-cell non-Hodgkin lymphoma (B-cell NHL) is the second commonest malignancy in the stomach. We determined the distribution ofHelicobacter pyloriouter membrane protein Q (HopQ) allelic type, cytotoxin-associated gene (cag)-pathogenicity activity island (cag-PAI) and vacuolation activating cytotoxin A (vacA) genes, respectively, in patients with B-cell NHL. We also compared them with their distribution in non-ulcer dyspepsia (NUD).H. pyloriwas cultured from gastric biopsy tissue obtained at endoscopy. Polymerase chain reaction was performed. Of 170 patients enrolled, 114 (63%) had NUD and 56 (37%) had B-cell NHL. HopQ type 1 was positive in 66 (58%) in NUD compared with 46 (82%) (P= 0·002) in B-cell NHL; HopQ type 2 was positive in 93 (82%) with NUD compared with 56 (100%) (P< 0·001) in B-cell NHL. Multiple HopQ types were present in 46 (40%) in NUD compared with 46 (82%) (P< 0·001) in B-cell NHL. CagA was positive in 48 (42%) in NUDvs. 50 (89%) (P< 0·001) in B-cell NHL; cagT was positive in 35 (31%) in NUDvs. 45 (80%) (P< 0·001) in B-cell NHL; left end of thecagAgene (LEC)1 was positive in 23 (20%) in NUDvs. 43 (77%) (P< 0·001) in B-cell NHL. VacAs1am1 positive in B-cell NHL in 48 (86%) (P< 0·001)vs. 50 (44%) in NUD, while s1am2 was positive in 20 (17%) in NUDvs. 46 (82%) (P< 0·001) in B-cell NHL.H. pyloristrains with multiple HopQ allelic types, truncated cag-PAI evidenced by expression of cagA, cagT and cag LEC with virulent vacAs1 alleles are associated with B-cell NHL development.

Analysis of Antibodies to Newly Described Plasmodium falciparum Merozoite Antigens Supports MSPDBL2 as a Predicted Target of Naturally Acquired Immunity

ABSTRACTProspective studies continue to identify malaria parasite genes with particular patterns of polymorphism which indicate they may be under immune selection, and the encoded proteins require investigation. Sixteen new recombinant protein reagents were designed to characterize three such polymorphic proteins expressed inPlasmodium falciparumschizonts and merozoites: MSPDBL1 (also termed MSP3.4) and MSPDBL2 (MSP3.8), which possess Duffy binding-like (DBL) domains, and SURFIN4.2, encoded by a member of the surface-associated interspersed (surf) multigene family. After testing the antigenicities of these reagents by murine immunization and parasite immunofluorescence, we analyzed naturally acquired antibody responses to the antigens in two cohorts in coastal Kenya in which the parasite was endemic (Chonyi [n= 497] and Ngerenya [n= 461]). As expected, the prevalence and levels of serum antibodies increased with age. We then investigated correlations with subsequent risk of clinical malaria among children <11 years of age during 6 months follow-up surveillance. Antibodies to the polymorphic central region of MSPDBL2 were associated with reduced risk of malaria in both cohorts, with statistical significance remaining for the 3D7 allelic type after adjustment for individuals' ages in years and antibody reactivity to whole-schizont extract (Chonyi, risk ratio, 0.51, and 95% confidence interval [CI], 0.28 to 0.93; Ngerenya, risk ratio, 0.38, and 95% CI, 0.18 to 0.82). For the MSPDBL1 Palo Alto allelic-type antigen, there was a protective association in one cohort (Ngerenya, risk ratio, 0.53, and 95% CI, 0.32 to 0.89), whereas the other antigens showed no protective associations after adjustment. These findings support the prediction that antibodies to the polymorphic region of MSPDBL2 contribute to protective immunity.

Molecular Ecology of Listeria monocytogenes and Other Listeria Species in Small and Very Small Ready-to-Eat Meat Processing Plants

A longitudinal study was conducted to track Listeria contamination patterns in ready-to-eat meats from six small or very small meat processing plants located in three states over 1 year. A total of 688 environmental sponge samples were collected from nonfood contact surfaces during bimonthly visits to each plant. Overall, L. monocytogenes was isolated from 42 (6.1%) environmental samples, and its prevalence ranged from 1.7 to 10.8% across different plants. Listeria spp., other than L. monocytogenes, were isolated from 9.5% of samples overall, with the prevalence ranging from 1.5 to 18.3% across different plants. The prevalence of L. monocytogenes correlated well with that of other Listeria spp. for some but not all plants. One L. monocytogenes isolate representing each positive sample was characterized by molecular serotyping, EcoRI ribotyping, and pulsed-field gel electrophoresis typing. Seven sample sites tested positive for L. monocytogenes on more than one occasion, and the same ribotype was detected more than once at five of these sites. Partial sigB sequencing was used to speciate other Listeria spp. isolates and assign an allelic type to each isolate. Other Listeria spp. were isolated more than once from 14 sample sites, and the same sigB allelic type was recovered at least twice from seven of these sites. One plant was colonized by an atypical hemolytic L. innocua strain. Our findings indicate that small and very small meat processing plants that produce ready-to-eat meat products are characterized by a varied prevalence of Listeria, inconsistent correlation between contamination by L. monocytogenes and other Listeria spp., and a unique Listeria molecular ecology.