Serological Evidence of Chikungunya Virus among Acute Febrile Patients in Southern Mozambique

Background

In the last two decades, chikungunya virus (CHIKV) has rapidly expanded to several geographical areas, causing frequent outbreaks in sub-Saharan Africa, South East Asia, South America, and Europe. Therefore, the disease remains heavily neglected in Mozambique, and no recent study has been conducted.

Methods

Between January and September 2013, acute febrile patients with no other evident cause of fever and attending a health center in a suburban area of Maputo city, Mozambique, were consecutively invited to participate. Paired acute and convalescent serum samples were requested from each participant. Convalescent samples were initially screened for anti-CHIKV IgG using a commercial indirect immunofluorescence test, and if positive, the corresponding acute sample was screened using the same test.

Results

Four hundred patients were enrolled. The median age of study participants was 26 years (IQR: 21–33 years) and 57.5% (224/391) were female. Paired blood samples were obtained from 209 patients, of which 26.4% (55/208) were presented anti-CHIKV IgG antibodies in the convalescent sample. Seroconversion or a four-fold titer rise was confirmed in 9 (4.3%) patients.

Conclusion

The results of this study strongly suggest that CHIKV is circulating in southern Mozambique. We recommend that CHIKV should be considered in the differential diagnosis of acute febrile illness in Mozambique and that systematic surveillance for CHIKV should be implemented.     

Complete Genome Sequence of Vibrio parahaemolyticus Bacteriophage vB_VpaM_MAR

Vibrio parahaemolyticus is a major pathogen that is mainly associated with seafood and is a global food safety issue. Our objective was to isolate and completely sequence a specific phage against this bacterium. Phage vB_VpaM_MAR is able to lyse 76% of the V. parahaemolyticus strains tested. MAR belongs to the Myoviridae family and has a genome comprised of double-stranded DNA with a size of 41,351 bp, a G+C content of 51.3%, and 62 open reading frames (ORFs). Bioinformatic analysis showed that phage MAR is closely related to Vibrio phages VHML, VP58.5, and VP882 and Halomonas aquamarina phage ΦHAP-1.     

Contribution of the National Mycology Laboratory Network to Surveillance of Cryptococcosis in Argentina

Purpose of Review

Cryptococcal meningitis is the most common fungal infection of the central nervous system and the third most frequent neurological complication in AIDS patients. To understand the Argentinean epidemiology of cryptococcosis, several efforts have been made by the National Reference Laboratory in Clinical Mycology.

Recent Findings

In Argentina, reports of distribution and frequency of Cryptococcus neoformans and Cryptococcus gattii isolates are scarce and very little is known about its circulating genotypes and mating types. The National Mycology Laboratory Network and the National Reference Laboratory in Clinical Mycology joined forces to estimate the prevalence of cryptococcosis and to obtain and to analyse epidemiological data of this important fungal infection.

Summary

Data presented here were recovered from 1998 to 2016 and represents an approximation to the actual situation of cryptococcosis in Argentina. These results could be useful to design future investigations.

     

Isolation and partial characterization of three isoamylases of Rhyzopertha dominica F. (Coleoptera: Bostrichidae)

Three isoamylases of Rhyzopertha dominica (termed RdA70, RdA79, and RdA90 according to their relative mobility in gel electrophoresis) were isolated by ammonium sulfate fractionation and hydrophobic interaction chromatography. RdA70 and RdA79 showed an optimal pH of 7.0, whereas for RdA90 the optimal pH was 6.5. The three isoamylases remained stable at 50 °C for 1 h, but at 60 °C, all lost 50% of their activity in 20 min and were completely inactivated in 1 h. RdA70 and RdA79 were inhibited by albumin extracts from wheat samples varying widely in amylase inhibitory activity; however, RdA90 was highly resistant to inhibition. β-Mercaptoethanol up to 30 mM increased the activity of the three isoamylases by 2.5-fold. The action pattern of the three isoamylases was typical of endoamylases; however, differences were observed on the hydrolytic efficiency rates measured as V_max/K_m ratio on starch, amylopectin, and amylose. The hydrolyzing action of RdA90 on starch and amylopectin (V_max/K_m = 90.4 ± 2.3 and 78.9 ± 6.6, respectively) was less efficient than that on amylose (V_max/K_m = 214 ± 23.2). RdA79 efficiently hydrolyzed both amylopectin and amylose (V_max/K_m = 260.6 ± 12.9 and 326.5 ± 9.4, respectively). RdA70 hydrolyzed starch and amylose at similar rates (V_max/K_m = 202.9 ± 5.5 and 215.9 ± 6.2, respectively), but amylopectin was a poor substrate (V_max/K_m = 124.2 ± 7.4). The overall results suggest that RdA70 and RdA79 appear to belong to a group of saccharifying isoamylases that breaks down long fragments of oligosaccharide chains produced by the hydrolytic action of RdA90. The simultaneous action of the three isoamylases on starch, aside from the high resistance of RdA90 to wheat amylase inhibitors, might allow R. dominica to feed and reproduce successfully on the wheat kernel.     

Capturing Intracellular pH Dynamics by Coupling Its Molecular Mechanisms within a Fully Tractable Mathematical Model

We describe the construction of a fully tractable mathematical model for intracellular pH. This work is based on coupling the kinetic equations depicting the molecular mechanisms for pumps, transporters and chemical reactions, which determine this parameter in eukaryotic cells. Thus, our system also calculates the membrane potential and the cytosolic ionic composition. Such a model required the development of a novel algebraic method that couples differential equations for slow relaxation processes to steady-state equations for fast chemical reactions. Compared to classical heuristic approaches based on fitted curves and ad hoc constants, this yields significant improvements. This model is mathematically self-consistent and allows for the first time to establish analytical solutions for steady-state pH and a reduced differential equation for pH regulation. Because of its modular structure, it can integrate any additional mechanism that will directly or indirectly affect pH. In addition, it provides mathematical clarifications for widely observed biological phenomena such as overshooting in regulatory loops. Finally, instead of including a limited set of experimental results to fit our model, we show examples of numerical calculations that are extremely consistent with the wide body of intracellular pH experimental measurements gathered by different groups in many different cellular systems.     

Genome Sequence of Cronobacter sakazakii Myovirus vB_CsaM_GAP31

Cronobacter sakazakii is a pathogen that predominantly infects immunocompromised individuals, especially infants, where it causes meningitis. The genome of lytic C. sakazakii myovirus vB_CsaM_GAP31 has been fully sequenced. It consists of 147,940 bp and has a G+C content of 46.3%. A total of 295 genes, including 269 open reading frames and 26 tRNA genes, were identified. This phage is related to Salmonella phage PVP-SE1 and coliphages vB_EcoM-FV3 and rV5.     

KIF13A drives AMPA receptor synaptic delivery for long-term potentiation via endosomal remodeling

The regulated trafficking of AMPA-type glutamate receptors (AMPARs) from dendritic compartments to the synaptic membrane in response to neuronal activity is a core mechanism for long-term potentiation (LTP). However, the contribution of the microtubule cytoskeleton to this synaptic transport is still unknown. In this work, using electrophysiological, biochemical, and imaging techniques, we have found that one member of the kinesin-3 family of motor proteins, KIF13A, is specifically required for the delivery of AMPARs to the spine surface during LTP induction. Accordingly, KIF13A depletion from hippocampal slices abolishes LTP expression. We also identify the vesicular protein centaurin-α1 as part of a motor transport machinery that is engaged with KIF13A and AMPARs upon LTP induction. Finally, we determine that KIF13A is responsible for the remodeling of Rab11-FIP2 endosomal structures in the dendritic shaft during LTP. Overall, these results identify specific kinesin molecular motors and endosomal transport machinery that catalyzes the dendrite-to-synapse translocation of AMPA receptors during synaptic plasticity.     

Prospective Multicenter Study of Community-Associated Skin and Skin Structure Infections due to Methicillin-Resistant Staphylococcus aureus in Buenos Aires,Argentina

Background

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is now the most common cause of skin and skin structure infections (SSSI) in several world regions. In Argentina prospective, multicenter clinical studies have only been conducted in pediatric populations.

Objective

Primary: describe the prevalence, clinical and demographic characteristics of adult patients with community acquired SSSI due to MRSA; secondary: molecular evaluation of CA-MRSA strains. Patients with MRSA were compared to those without MRSA.

Materials and Methods

Prospective, observational, multicenter, epidemiologic study, with molecular analysis, conducted at 19 sites in Argentina (18 in Buenos Aires) between March 2010 and October 2011. Patients were included if they were ≥14 years, were diagnosed with SSSI, a culture was obtained, and there had no significant healthcare contact identified. A logistic regression model was used to identify factors associated with CA-MRSA. Pulse field types, SCCmec, and PVL status were also determined.

Results

A total of 311 patients were included. CA-MRSA was isolated in 70% (218/311) of patients. Clinical variables independently associated with CA-MRSA were: presence of purulent lesion (OR 3.29; 95%CI 1.67, 6.49) and age <50 years (OR 2.39; 95%CI 1.22, 4.70). The vast majority of CA-MRSA strains causing SSSI carried PVL genes (95%) and were SCCmec type IV. The sequence type CA-MRSA ST30 spa t019 was the predominant clone.

Conclusions

CA-MRSA is now the most common cause of SSSI in our adult patients without healthcare contact. ST30, SCCmec IV, PVL+, spa t019 is the predominant clone in Buenos Aires, Argentina.     

Heterotrophic bacterial production in Lake Xolotlán (Managua) during 1988–1989

The biomass and production (thymidine incorporation) of heterotrophic bacterioplankton has been assessed from July, 1988, to October, 1989. in Lake Xolotlán, Nicaraqua. Bacterial abundance was high, 2–3.10¹⁰ cells.l^–1, and bacterial biomass averaged ca. 0.75 mg C.l^–1, or roughly 20% of the partivculate organic carbon. Bactrial production averaged between 3.5–5 g C.l^–1.h^–1 and on a areal basis was 650–959 mg C.m^–2.d^–1 or 13–20% ofthe primary production. Although bacterial production (volumetric basis) was typical for eutrophic lakeks, the bacterial specific growth rate was low, the bacteial population doubling time was ca. 1 week, perhaps indicating that there was a low grazing pressure on the bacteria.     

Spatial extent of analysis influences observed patterns of population genetic structure in a widespread darter species (Percidae)

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