Alan John Alexander McBride

Human toxocariasis: current advances in diagnostics, treatment, and interventions

Toxocariasis is a neglected zoonosis caused by the nematodes Toxocara canis and Toxocara cati. This disease is widespread in many countries, reaching high prevalence independently of the economic conditions. However, the true number of cases of toxocariasis is likely to be underestimated owing to the lack of adequate surveillance programs. Although some diagnostic tests are available, their sensitivity and specificity need to be improved. In addition, treatment options for toxocariasis are limited and are non-specific. Toxocariasis is listed as one of the five most important neglected diseases by the CDC. This review presents recent advances related to the control of toxocariasis, including new immunodiagnostics, therapies, and drug formulations, as well as novel interventions using DNA vaccines, immunomodulators, and probiotics.

Substituted diaryl diselenides: Cytotoxic and apoptotic effect in human colon adenocarcinoma cells

AIMS To investigate the effects and study the underlying cell death mechanisms of diaryl diselenides, including: diphenyl diselenide (C(6)H(5)Se)(2); 4-chlorodiphenyl diselenide (4-ClC(6)H(4)Se)(2); 3-(trifluoromethyl)-diphenyl diselenide (3-CF(3)C(6)H(4)Se)(2) and 4-methoxydiphenyl diselenide (4-MeOC(6)H(4)Se)(2), on the human colon adenocarcinoma cell line HT-29. MAIN METHODS The viability of HT-29 cells after exposure to the diaryl diselenides and its substituted structures was based on the MTT assay. To verify if cell death was mediated throughout apoptosis mechanisms, flow cytometry and real-time PCR (qPCR) analyses were conducted. KEY FINDINGS The MTT assay and flow cytometry analyses showed that (3-CF(3)C(6)H(4)Se)(2) and (4-MeOC(6)H(4)Se)(2) induced cytotoxicity through apoptosis mechanisms in HT-29 cells. qPCR revealed there was an up-regulation of pro-apoptotic (Bax, casapase-9, caspase-8, apoptosis-inducing factor (AIF) and Endonuclease G (EndoG)) and cell-cycle arrest genes (p53 and p21) and down-regulation of anti-apoptotic (Bcl-2 and survivin) and Myc genes. SIGNIFICANCE These results demonstrate that (3-CF(3)C(6)H(4)Se)₂ and (4-MeOC(6)H(4)Se)(2) have the potential to induce apoptosis in HT-29 cells through the activation of caspase-dependent and independent pathways and through cell-cycle arrest.

Draft genome of the Leptospira interrogans strains, Acegua, RCA, Prea, and Capivara, obtained from wildlife maintenance hosts and infected domestic animals

In the present paper, we announce new draft genomes of four Leptospira interrogans strains named Acegua, RCA, Prea, and Capivara. These strains were isolated in the state of Rio Grande do Sul, Brazil, from cattle, dog, Brazilian guinea pig, and capybara, respectively.

Characterization of a virulent Leptospira interrogans strain isolated from an abandoned swimming pool

Pathogenic Leptospira spp. are the etiological agents of leptospirosis, an important disease of both humans and animals. In urban settings, L. interrogans serovars are the predominant cause of disease in humans. The purpose of this study was to characterize a novel Leptospira isolate recovered from an abandoned swimming pool. Molecular characterization through sequencing of the rpoB gene revealed 100% identity with L. interrogans and variable-number tandem-repeat (VNTR) analysis resulted in a banding pattern identical to L. interrogans serogroup Icterohaemorrhagiae, serovar Copenhageni or Icterohaemorrhagiae. The virulence of the strain was determined in a hamster model of lethal leptospirosis. The lethal dose 50% (LD50) was calculated to be two leptospires in female hamsters and a histopathological examination of infected animals found typical lesions associated with severe leptospirosis, including renal epithelium degeneration, hepatic karyomegaly, liver-plate disarray and lymphocyte infiltration. This highly virulent strain is now available for use in further studies, especially evaluation of vaccine candidates.

Expression of apoptotic genes in immature and in vitro matured equine oocytes and cumulus cells.

The gene expression of Bax, Bcl-2, survivin and p53, following in vitro maturation of equine oocytes, was compared in morphologically distinct oocytes and cumulus cells. Cumulus-oocyte complexes (COC) were harvested and divided into two groups: G1 - morphologically healthy cells; and G2 - less viable cells or cells with some degree of atresia. Total RNA was isolated from both immature and in vitro matured COC and real-time reverse transcription polymerase chain reaction (qRT-PCR) was used to quantify gene expression. Our results showed there was significantly higher expression of survivin (P < 0.05) and lower expression of p53 (P < 0.01) in oocytes compared with cumulus cells in G1. No significant difference in gene expression was observed following in vitro maturation or in COC derived from G1 and G2. However, expression of the Bax gene was significantly higher in cumulus cells from G1 (P < 0.02).

Simplified recovery process of Ralstonia solanacearum-synthesized polyhydroxyalkanoates via chemical extraction complemented by liquid-liquid phase separation

Poly (3-hydroxybutyrate) (P(3HB)) is the most studied thermoplastic biopolymer belonging to the polyhydroxyalkanoate (PHA) family, the main features of which include rapid biodegradability and biocompatibility. The bioplastic recovery process is an important step during production and can directly influence the characteristics of PHAs. However, more efficient methods for the production of P(3HB) are necessary to make it economically viable. The aim of the present study was to improve the standard, chloroform-based, extraction step for the recovery of P(3HB). The polymer was produced using a Ralstonia solanacearum strain. The following parameters were improved in the recovery process: heating time, separation method (filtration or liquid-liquid phase separation), biomass state (fresh or dry cell concentrate) and the solvent:biomass ratio. By improving the chemical extraction of P(3HB) we recovered 98% of the cumulative polymer and reduced the heating time by 75%. Furthermore, we improved the separation process and developed an extraction solution that was faster and more economical.

DNA vaccines against leptospirosis: A literature review

Leptospirosis is an infectious disease caused by pathogenic Leptospira species. The vaccines that are currently available for leptospirosis are composed of whole-cell preparations and suffer from limitations such as low efficacy, multiple side-effects, poor immunological memory and lack of cross-protection against different serovars of Leptospira spp. In light of the global prevalence of this disease, the development of a more effective vaccine against leptospirosis is of paramount importance. Genetic immunization is a promising alternative to conventional vaccine development. In the last 25years, several novel strategies have been developed for increasing the efficacy of DNA vaccines. Examples of such strategies include the introduction of novel plasmid vectors, adjuvants, alternate delivery routes, and prime-boost regimens. Herein we discuss the latest and most promising advances that have been made in developing DNA vaccines against leptospirosis. We also deliberate over the future directions that must be undertaken in order to improve results in this field.

Overview of Leptospirosis

Leptospirosis has re-emerged as serious public health problem that is no longer limited to those who work and live in a rural setting [1]. The migration of poverty-stricken individuals to urban settings, together with climate change, has resulted in dramatic increases in the incidence of leptospirosis worldwide [2], particularly in tropical and subtropical developing countries [3, 4]. Leptospirosis is caused by pathogenic Leptospira spp. that have been characterized into >300 serovars [5]. Urban leptospirosis is mainly spread by rats that have proved difficult if not impossible to control. Rural leptospirosis is equally difficult to control due to the plethora of animal reservoirs and transmission between wild and domestic animal hosts. To further complicate matters, clinical diagnosis of leptospirosis is difficult as the symptoms are similar to febrile illnesses caused by dengue, Zika, chikungunya, hantavirus, as well as viral hepatitis and malaria. Laboratory diagnosis is carried out using the WHO-recommended microagglutination test (MAT), yet this is not widely available and is usually limited to reference laboratories [6]. The MAT requires two serum samples taken during the acute and convalescent phase of the disease so it has limited application to patient management. Alternative, commercially available, diagnostic tests are typically based on whole-cell antigens (inactivated leptospires), and sensitivity and specificity during the acute phase are highly variable (28–71%) [7, 8]. Therefore, there is an urgent need for new diagnostic tests that are faster and able to detect the disease at an early stage and that may be performed in areas having limited laboratory capacity, allowing for the rapid initiation of treatment of the patient. Inactivated vaccines, known as bacterins, are highly effective against the target serovar, but they are poorly cross-protective against other serovars and can cause severe side effects, and few countries around the world have approved their use as human vaccines [9]. Severe leptospirosis is life-threatening and can manifest as acute kidney injury (AKI), the classic manifestation of Weil’s disease, and more recently as leptospirosis pulmonary haemorrhage syndrome (LPHS) [10]. The aim of this chapter is to provide an overview of human leptospirosis and its causative agent, the pathogenic Leptospira spp.

Cytokine expression profile in hamsters immunized with OmpL37 from Leptospirainterrogans in different vaccine formulations

Background Pathogenic spirochetes from the genus Leptospira are the bacteria that cause leptospirosis, an emerging zoonosis responsible for over 500,000 human cases each year [1]. Vaccination with inactivated whole-cell preparations (bacterins) has limited efficacy due to the wide antigenic variation of the pathogen. Bacterins are reactogenic and confers serovar specific and short-term immunity [2]. The protein OmpL37 represents a potential target for vaccine development against leptospirosis since it is recognized by human and animal serum, binds human extracellular matrix components, is up-regulated in vivo and conserved among pathogenic leptospires [3]. We aimed to evaluate the immune response induced by OmpL37 from L. interrogans serovar Copenhageni strain Fiocruz L1-130 in hamsters, using prime-boost, DNA, and protein-based immunizations.

Development of a recombinant protein based Dot-Blot for the diagnosis of canine leptospirosis

Background Leptospirosis is a globally disseminated zoonosis, recognized as a re-emergent neglected disease [1] and the causative pathogens are spirochetes from genus Leptospira [2]. In Brazil, more than 100.00 leptospirosis cases are reported annually, with outbreaks emerging especially during floods [3]. The microscopic agglutination test (MAT) is considered the standard serological test for the diagnosis of leptospirosis, but it requires paired serum samples, is demanding, difficult to analyse and the results can be variable when compared between laboratories [2]. The absence of an adequate laboratorial diagnosis is the main barrier for the implementation of disease surveillance for the control of both human and animal leptospirosis. Hence, there is an urgent need for the development of an adequate laboratorial test that is both quick and reliable. Apart from the danger connected to rodents, which are leptospires main vectors, occurrence of the disease in dogs can generate a higher risk of infection for humans [4]. In the current study, selected recombinant proteins from L. interrogans were tested for their diagnostic potential using a Dot-Blot technique against a canine serum panel previously characterized by the MAT and a whole-cell Leptospira indirect ELISA.