Whole-Genome Sequencing Characterization of Virulence Profiles of Listeria monocytogenes Food and Human Isolates and In Vitro Adhesion/Invasion Assessment

Listeria monocytogenes (Lm) is the causative agent of human listeriosis. Lm strains have different virulence potential. For this reason, we preliminarily characterised via Whole-Genome Sequencing (WGS) some Lm strains for their key genomic features and virulence-associated determinants, assigning the clonal complex (CC). Moreover, the ability of the same strains to adhere to and invade human colon carcinoma cell line Caco-2, evaluating the possible correspondence with their genetic virulence profile, was also assessed. The clinical strains typed belonged to clonal complex (CC)1, CC31, and CC101 and showed a very low invasiveness. The Lm strains isolated from food were assigned to CC1, CC7, CC9, and CC121. All CC1 carried the hypervirulence pathogenicity island LIPI-3 in addition to LIPI-1. Premature stop codons in the inlA gene were found only in Lm of food origin belonging to CC9 and CC121. The presence of LIPI2_inlII was observed in all the CCs except CC1. The CC7 strain, belonging to an epidemic cluster, also carried the internalin genes inlG and inlL and showed the highest level of invasion. In contrast, the human CC31 strain lacked the lapB and vip genes and presented the lowest level of invasiveness. In Lm, the genetic determinants of hypo- or hypervirulence are not necessarily predictive of a cell adhesion and/or invasion ability in vitro. Moreover, since listeriosis results from the interplay between host and virulence features of the pathogen, even hypovirulent clones are able to cause infection in immunocompromised people.

Non-coding RNA regulates phage sensitivity in Listeria monocytogenes

Non-coding RNAs (ncRNAs) have gained increasing attention as their diverse roles in virulence and environmental stress in Listeria monocytogenes have become clearer. The ncRNA rliB is an atypical member of the CRISPR family, conserved at the same genomic locus in all analyzed L. monocytogenes genomes and also in other Listeria species. In this study, rliB defective mutants (Lm3-22-ΔrliB) were constructed by homologous recombination. The growth cycle of Lm3-22-ΔrliB mutants was slower than that of wild-type Lm3-22. The sensitivity of Lm3-22-ΔrliB to the Listeria phage vB-LmoM-SH3-3 was significantly increased, and the efficiency of plaque formation was enhanced by 128 fold. Compared with wild type, the adhesion and invasion of Lm3-22-ΔrliB decreased significantly (9.3% and 1.33%, respectively). After 4 hours of infection, the proliferation of Lm3-22-ΔrliB in RAW264.7 cells also decreased significantly. Transcription level of invasion-related surface proteins showed that the internalin genes lmo0610 and lm0514, and the peptidoglycan binding protein gene lmo1799 in Lm3-22-ΔrliB were significantly increased. In addition, after interaction with phage, the transcription levels of inlA, lmo0610, lmo1799, lmo2085, and lmo0514 in Lm3-22-ΔrliB cells were significantly upregulated, while inlB was downregulated, compared with Lm3-22 control group with phage treatment. Therefore, rliB deletion effectively regulated the interaction between Listeria and phage, weaken its invasion ability, and provided a new theoretical basis for biocontrol of phage.

INVASÃO POR GRAMÍNEAS EXÓTICAS EM CAMPOS SOBRE PALEODUNAS: EFEITOS NA DIVERSIDADE FLORÍSTICA

O Refúgio de Vida Silvestre Banhado dos Pachecos localiza-se sobre a Coxilha das Lombas, Viamão/RS, e encontra-se em processo de invasão biológica por gramíneas exóticas na área de campo seco. Este fragmento de vegetação campestre sobre paleodunas é habitat da espécie endêmica Ctenomys lami (Rodentia, Ctenomydae) e apresenta composição florística peculiar em relação a maioria das áreas naturais dos Campos Sulinos, com espécies de Asteraceae sendo dominantes em comparação às espécies de Poaceae. Com o objetivo de caracterizar a composição florística e avaliar o grau e efeitos da invasão biológica sobre a comunidade de campo seco foi realizado um levantamento quantitativo. Foram amostradas 31 parcelas de 1 x 1 m e levantados dados de cobertura e altura da vegetação, solo descoberto e serrapilheira. Foram calculados parâmetros fitossociológicos para cada espécie. As parcelas foram classificadas quanto ao nível de invasão por gramíneas exóticas. O efeito da invasão sobre a composição e estrutura da vegetação foi avaliado a partir de Análise de Coordenadas Principais, regressão linear e análise de variância. As gramíneas exóticas invasoras Urochloa decumbens e Digitaria eriantha subsp. pentzii foram dominantes em grande parte da vegetação campestre, modificando a estrutura e composição vegetal conforme o nível de invasão. Cerca de um terço da área encontra-se altamente invadida. Ações de remoção e controle de invasoras se fazem urgentes, considerando que este é um dos poucos fragmentos de ecossistemas naturais abertos na Coxilha das Lombas e abriga espécies ameaçadas de extinção. INVASION BY EXOTIC GRASSES IN GRASSLAND ON PALAEODUNES: EFFECTS ON FLORISTIC DIVERSITY. The Banhado dos Pachecos Wildlife Refuge, located in the Coxilha das Lombas, in Viamão/RS, Brazil, is under a process of invasion by alien grasses in its areas of dry grassland. The grassland on palaeo-dunes is the habitat of the endemic species Ctenomys lami (Rodentia, Ctenomydae) and presents a peculiar floristic composition in relation to most natural grasslands in southern Brazil, with species of the Asteraceae dominating in comparison to grasses. In order to characterize the floristic composition and to evaluate the degree and effects of biological invasion on the grassland community, a quantitative vegetation survey was carried out. In 31 plots of 1 x 1 m, data on cover and height of vegetation, bare soil and litter were collected. Phytosociological parameters were calculated for each species. The plots were classified according to the level of invasion by exotic grasses and Principal Coordinate Analysis, linear regression and Analysis of Variance were performed to observe the species distribution in the community and the effects of the invasion on the richness and structure of the vegetation. The invasive exotic grasses Urochloa decumbens and Digitaria eriantha subsp.pentzii were dominant in grassland vegetation, modifying plant structure and composition according to the level of invasion. About a third of the area is heavily invaded. Invasive removal and control actions are urgent as this is one of the few fragments of natural grasslands in the Coxilha das Lombas and is habitat to species threatened with extinction.

Can an invasive African grass affect carbon and nitrogen stocks in open habitats of the Brazilian Cerrado?

Considering the emergence of ecosystems dominated by invasive species, there is growing interest in estimating the effect of biological invasions in ecosystem processes and provision of services. African grasses are the most invasive plants in the Cerrado (Brazilian savanna), but their impact on C and N stocks is poorly known. We compared patterns of C and N stocks in the aboveground biomass, root biomass and soil in open Cerrado (campo sujo) sites, both uninvaded and invaded by the African grass Urochloa decumbens. In both sites we estimated the aboveground biomass of U. decumbens and native grasses, as well as the root biomass up to 50 cm. We obtained C and N contents in the soil, as well as C and N stocks, up to 1 m depth, and variation in soil δ13C and δ15N. Although invasion did not affect the aboveground biomass, it did affect belowground biomass, leading to higher C stock in fine roots and soil N content close to soil surface, as well as higher C content along the soil profile. C and N soil stocks, soil δ13C and δ15N values did not significantly differ between invaded and uninvaded site. Even a relatively low level of invasion by U. decumbens changed the root distribution pattern and increased C and N contents in the upper soil, which may promote ecosystem changes by altering nutrient dynamics. Although still preliminary, our study shows that dominance by U. decumbens can have severe effects in the Cerrado belowground environment.

SEASONAL DYNAMICS OF HELMINTHOFAUNA OF WILD PREDATORY MAMMALS IN THE CONDITIONS OF KARAKALPAKSTAN

It has been studied the seasonal dynamics of helminthiasis of predatory animals in the territory of Karakalpakstan. The material was collected in 2017–2020 on the territory of Karakalpakstan. 273 predatory animals and dogs were subjected to a complete helminthological study by the method of K.I. Skyarbin (1928). In addition, 165 fecal samples were examined by helminthicaprological methods and using the compression method. As a result of the studies conducted in the biocenoses of Karakalpakstan, it was found that 53 species of helminthes parasitize in the body of wild predatory mammals, which belong to 39 genera, 25 families, 13 orders, 4 classes and 3 types. Of these, 17 species (32%) were cestodes, 4 (7.6%) were trematodes, 3 (5.7%) were acanthocephales, and 29 species (54.7%) were nematodes. In Karakalpakstan, predators become infected with helminthes throughout the year. The highest level of invasion was recorded in autumn (63.5%), followed by summer (55.7%), winter (46.3%) and spring (24.4%). We note that the infestation of animals increases 2.6 times in autumn compared to spring. In the conditions of Karakalpakstan, the season has a certain effect on the helminthes fauna of wild animals.

STRATEGY FOR THE DIAGNOSTICS OF TOXOPLASMOSIS IN DIFFERENT POPULATION GROUPS

The analysis of laboratory examination of the population with latent and chronic toxoplasmosis has a number of complexities. Therefore, the search for accurate biomarkers of toxoplasmosis to differentiate the stage of invasion development is very important. From the group of 559 persons, the infection of T. gondii was found in 27,9%. It is shown that a person is more often infected in childhood, teenage years and adolescence, which is marked by the presence of IgM antibodies and high levels of IgG antibodies. It was confirmed that IgA antibodies is an effective marker of reactivation of latent toxoplasmosis. The laboratory determination of toxoplasmosis markers showed a significant heterogeneity of the study group in terms of the level of invasion, depending on age, as well as the possibility to identify the stage and duration of the disease, including reactivation. Keyword: toxoplasmosis, antibody detection, latent invasion, reactivation, immunological diagnostics

Does morphology have real impact on local and distant recurrences in head and neck cutaneous melanoma?

Introduction. The term “local recurrence” is usually understood as regrowth of a tumor after surgical treatment. The regrowth appears within 3–5 cm from postoperative cicatrix. The causes for such prolonged tumor growth or recurrence of patients with cutaneous melanoma are nonradical surgical treatment as well as satellite or transit metastases that were not removed in-block with primary tumor. A great number of clinical researches, aimed at examination of melanoma, its patterns, anatomical criteria and features of clinical course, gave an opportunity to separate satellite or transit metastases into an independent group. Such metastases are realized inside or subdermally, up to 2 cm or more than 2 cm from the primary tumor, yet, not reaching the location of the first regional barrier.The aim of the study is to define influence of the main prognostic factors such as tumor thickness according to Breslow, the level of invasion according to Clark and the presence of ulceration on the frequency of local recurrence with cutaneous melanoma of head and neck.Materials and methods. The research involved 174 patients with cutaneous melanoma of head and neck (1995–2014). According to our index of contraction of a skin flap (median 30 %) the true borders of resection were clearly defined within all the patients. Thereby, 3 groups were identified with the following resection margin: 1.0 cm, where followed-up treatment results were analyzed.Results. Progression-free survival didn’t correlate with the size of surgical resection margins. The survival rates were the best with the lowest resection margin under 0.5 cm (77.3 %) and the worst with the highest resection margin more then 1.0 cm (38.7 %). That means that the treatment results don’t depend on the width increase of tumor resection margin.Conclusions. We consider that clear surgical margins for any thickness of cutaneous melanoma of head and neck should be as follows: 4 mm – 0.72 mm (p = 0.016). In our work, the influence of the main prognostic factors, such as tumor thickness according to Breslow, level of invasion according to Clark and ulceration on the frequency of head and neck cutaneous melanoma local recurrences had no impact.

A Clinicoepidemiological Study of Melanoma in Young Patients (20 Years of Age or Less) in Alberta, Canada, From 1992 to 2011

The epidemiological trends of malignant melanoma have been well described in the literature. However, there remains a paucity of population-based studies assessing melanoma epidemiology in our younger patients (20 years of age or less). Other studies indicate that melanoma incidence has risen in pediatric populations over the last several decades and that these tumors may display different clinical characteristics from those arising in adult populations. We conducted a retrospective, population-based analysis of all incident cases of melanoma occurring in young patients aged ≤20 years in Alberta from 1992 to 2011. Information, including patient age, sex, anatomical location, date of diagnosis, histological subtype (if available), level of invasion, and date of death (if applicable), was obtained from the Alberta Cancer Registry. All cases occurring during a 10-year period from 1993 to 2011 have been reviewed. A total of 71 cases were diagnosed during this time (63% female and 37% male). Age range was 0-20 years (mean of 17.5 years). Truncal melanomas made up 36% of cases, while 28% occurred on the lower limbs, 17% on the upper limbs, and 18% in the head and neck region. Average Breslow thickness was 1.97 mm; 67% of tumors were less than 1 mm thick. Unfortunately, 8 of 71 patients died from their disease. Overall, the incidence of melanoma in patients aged ≤20 years appeared to decrease in Alberta in the past 20 years; however, there has been an increase in the thickness of melanoma at diagnosis, which needs to be addressed.