Molecular Epidemiology of Rotavirus A in Calves: Evolutionary Analysis of a Bovine G8P[11] Strain and Spatio-Temporal Dynamics of G6 Lineages in the Americas

Rotavirus A (RVA) causes diarrhea in calves and frequently possesses the G6 and P[5]/P[11] genotypes, whereas G8 is less common. We aimed to compare RVA infections and G/P genotypes in beef and dairy calves from major livestock regions of Argentina, elucidate the evolutionary origin of a G8 strain and analyze the G8 lineages, infer the phylogenetic relationship of RVA field strains, and investigate the evolution and spatio-temporal dynamics of the main G6 lineages in American countries. Fecal samples (n = 422) from diarrheic (beef, 104; dairy, 137) and non-diarrheic (beef, 78; dairy, 103) calves were analyzed by ELISA and semi-nested multiplex RT-PCR. Sequencing, phylogenetic, phylodynamic, and phylogeographic analyses were performed. RVA infections were more frequent in beef (22.0%) than in dairy (14.2%) calves. Prevalent genotypes and G6 lineages were G6(IV)P[5] in beef (90.9%) and G6(III)P[11] (41.2%) or mixed genotypes (23.5%) in dairy calves. The only G8 strain was phylogenetically related to bovine and artiodactyl bovine-like strains. Re-analyses inside the G8 genotype identified G8(I) to G8(VIII) lineages. Of all G6 strains characterized, the G6(IV)P[5](I) strains from "Cuenca del Salado" (Argentina) and Uruguay clustered together. According to farm location, a clustering pattern for G6(IV)P[5] strains of beef farms was observed. Both G6 lineage strains together revealed an evolutionary rate of 1.24 × 10-3 substitutions/site/year, and the time to the most recent common ancestor was dated in 1853. The most probable ancestral locations were Argentina in 1981 for G6(III) strains and the USA in 1940 for G6(IV) strains. The highest migration rates for both G6 lineages together were from Argentina to Brazil and Uruguay. Altogether, the epidemiology, genetic diversity, and phylogeny of RVA in calves can differ according to the production system and farm location. We provide novel knowledge about the evolutionary origin of a bovine G8P[11] strain. Finally, bovine G6 strains from American countries would have originated in the USA nearly a century before its first description.

Molecular characterization of multidrug-resistant Escherichia coli of the phylogroups A and C in dairy calves with meningitis and septicemia

Escherichia coli is an important cause of septicemia (SEPEC) and neonatal meningitis (NMEC) in dairy calves. However, the diversity of virulence profiles, phylogroups, antimicrobial resistance patterns, carriage of integron structures, and fluoroquinolone (FQ) resistance mechanisms have not been fully investigated. Also, there is a paucity of knowledge about the virulence profiles and frequency of potential SEPEC in feces from calves with or without diarrhea. This study aimed to characterize the virulence potential, phylogroups, antimicrobial susceptibility, integron content, and FQ-resistance mechanisms in Escherichia coli isolated from calves with meningitis and septicemia. Additionally, the virulence genes (VGs) and profiles of E. coli isolated from diarrheic and non-diarrheic calves were compared between them and together with NMEC and SEPEC in order to identify shared profiles. Tissue and fluid samples from eight dairy calves with septicemia, four of which had concurrent meningitis, were processed for bacteriology and histopathology. Typing of VGs was assessed in 166 isolates from diverse samples of each calf. Selected isolates were evaluated for antimicrobial susceptibility by the disk diffusion test. Phylogroups, integron gene cassettes cartography, and FQ-resistance determinants were analyzed by PCR, sequencing, and bioinformatic tools. Furthermore, 109 fecal samples and 700 fecal isolates from dairy calves with or without diarrhea were evaluated to detect 19 VGs by uniplex PCR. Highly diverse VG profiles were characterized among NMEC and SEPEC isolates, but iucD was the predominant virulence marker. Histologic lesions in all calves supported their pathogenicity. Selected isolates mainly belonged to phylogroups A and C and showed multidrug resistance. Classic (dfrA17 and arr3-dfrA27) and complex (dfrA17-aadA5::ISCR1::bla_CTX-M-2) class 1 integrons were identified. Target-site mutations in GyrA (S83L and D87N) and ParC (S80I) encoding genes were associated with FQ resistance. The VGs detected more frequently in fecal samples included f17G (50%), papC (30%), iucD (20%), clpG (19%), eae (16%), and afaE-8 (13%). Fecal isolates displaying the profiles of f17 or potential SEPEC were found in 25% of calves with and without diarrhea. The frequency of E. coli VGs and profiles did not differ between both groups (p > 0.05) and were identical or similar to those found in NMEC and SEPEC. Overall, multidrug-resistant E. coli isolates with diverse VG profiles and belonging to phylogroups A and C can be implicated in natural cases of meningitis and septicemia. Their resistance phenotypes can be partially explained by class 1 integron gene cassettes and target-site mutations in gyrA and parC. These results highlight the value of antimicrobial resistance surveillance in pathogenic bacteria isolated from food-producing animals. Besides, calves frequently shed potential SEPEC in their feces as commensals ("Trojan horse"). Thus, these bacteria may be disseminated in the farm environment, causing septicemia and meningitis under predisposing factors.

Estudio Retrospectivo de casos de Hemoglobinuria Bacilar Diagnosticados en bovinos de la provincia de Buenos Aires (Argentina)

La hemoglobinuria bacilar (HB) es una enfermedad infectocontagiosa, aguda, producida Clostridium haemolyticum, que afecta principalmente a bovinos y es predispuesta por diferentes factores. En este artículo se realiza un estudio retrospectivo de los casos de HB diagnosticados en bovinos de la provincia de Buenos Aires, por el Servicio de Diagnóstico Veterinario Especializado de INTA Balcarce durante el período 1969-2015 y los casos reportados por veterinarios privados en el Programa de Interacción Profesional en el área de influencia del Centro Regional Buenos Aires Sur del INTA durante el periodo 2001-2007. Se observó marcada estacionalidad de la enfermedad durante los meses de invierno y una asociación con un avanzado estado de preñez de los animales (88% de los casos). Solo en un 15,9 % de los casos se pudo confirmar una infestación simultánea con Fasciola hepatica en los rodeos donde se diagnosticó la enfermedad. En un 47,9 % de estos episodios los animales habían recibido previamente dos dosis de vacuna contra HB. HB es endémica e insidiosa en ciertas regiones de nuestro país. La información sobre algunos aspectos de su etiopatogenia y el control es escasa, dificultando su prevención. Estas áreas deberían ser exploradas en el futuro para tratar de mejorarlas.

A cartilage tissue engineering approach combining starch-polycaprolactone fibre mesh scaffolds with bovine articular chondrocytes

In the present work we originally tested the suitability of corn starch-polycaprolactone (SPCL) scaffolds for pursuing a cartilage tissue engineering approach. Bovine articular chondrocytes were seeded on SPCL scaffolds under dynamic conditions using spinner flasks (total of 4 scaffolds per spinner flask using cell suspensions of 0.5 x 10(6) cells/ml) and cultured under orbital agitation for a total of 6 weeks. Poly(glycolic acid) (PGA) non-woven scaffolds and bovine native articular cartilage were used as standard controls for the conducted experiments. PGA is a kind of standard in tissue engineering approaches and it was used as a control in that sense. The tissue engineered constructs were characterized at different time periods by scanning electron microscopy (SEM), hematoxylin-eosin (H&E) and toluidine blue stainings, immunolocalisation of collagen types I and II, and dimethylmethylene blue (DMB) assay for glycosaminoglycans (GAG) quantification assay. SEM results for SPCL constructs showed that the chondrocytes presented normal morphological features, with extensive cells presence at the surface of the support structures, and penetrating the scaffolds pores. These observations were further corroborated by H&E staining. Toluidine blue and immunohistochemistry exhibited extracellular matrix deposition throughout the 3D structure. Glycosaminoglycans, and collagen types I and II were detected. However, stronger staining for collagen type II was observed when compared to collagen type I. The PGA constructs presented similar features to SPCL at the end of the 6 weeks. PGA constructs exhibited higher amounts of matrix glycosaminoglycans when compared to the SPCL scaffolds. However, we also observed a lack of tissue in the central area of the PGA scaffolds. Reasons for these occurrences may include inefficient cells penetration, necrosis due to high cell densities, or necrosis related with acidic by-products degradation. Such situation was not detected in the SPCL scaffolds, indicating the much better biocompatibility of the starch based scaffolds.

Application of Plackett-Burman design and response surface methodology to achieve exponential growth for aggregated shipworm bacterium

Here we report the successful implementation of the Plackett-Burman multifactorial design to screen the limiting components for growth and subsequent use of the response surface methodology (RSM) to design a medium that supported exponential growth of the aggregated morphology of the shipworm bacterium, Teredinobacter turnirae. The results obtained with the help of Plackett-Burman design indicated limitations of three components in the growth medium, MnCl2.4H2O, Na2CO3, and K2HPO4. The concentrations of these three components were further optimized using RSM. By increasing the concentrations of the above-mentioned components by 4-fold, 12-fold, and 12-fold, respectively, it became possible to achieve exponential growth of the culture.

Production of an endoglucanase by the shipworm bacterium, Teredinobacter turnirae

The nutritional behavior of a cellulolytic nitrogen-fixing shipworm bacterium, Teredinobacter turnirae, is described, with respect to various carbon and nitrogen sources, in terms of endoglucanase production. Also, the effects of various surfactants on enzyme production are reported. Among the carbon sources, sucrose results in the maximum enzyme production, followed by cellulose. Ammonium phosphate proves to be the best nitrogen source for endoglucanase production. Various surfactants enhance the enzyme titers, with Triton X-100 yielding the best results. A combination of the above-mentioned components improves the enzyme production by 3.6-fold.

Pleomorphism of the marine bacterium Teredinobacter turnirae

AIMS

A morphology transition for the marine bacterium, Teredinobacter turnirae is reported.

METHODS AND RESULTS

When grown in the rod-shaped morphology, the cells require high concentrations of NaCl (0.3 mol x l(-1)) and secrete extracellular protease and endoglucanase activity. When this bacterium is grown in a medium containing casein as a sole carbon and nitrogen source, a major change in morphology to a stable aggregated form is obtained.

CONCLUSION

In the aggregated morphology, much higher protease production rates (170 Units x ml(-1) x d-1 for aggregates vs. 15 Units x ml(-1) x d(-1) for rods, for the same initial biomass) and negligible endoglucanase titres are obtained. In addition, the aggregated morphology does not require sodium chloride for growth.

SIGNIFICANCE AND IMPACT OF THE STUDY

The phenomenon reported here describes a novel relationship between the cell morphology and the biochemical characteristics of the bacterium.

Distribution of IS900 restriction fragment length polymorphism types among animal Mycobacterium avium subsp. paratuberculosis isolates from Argentina and Europe

Sixty-one Mycobacterium avium subsp. paratuberculosis isolates from cattle and deer from the Buenos Aires province, an important livestock region in Argentina, were typed by restriction fragment length polymorphisms (RFLP) analysis based on IS900. Four different RFLP patterns (designated 'A', 'B', 'C' and 'E') were identified in BstEII digests of genomic DNA. The most frequently observed type, pattern 'A', was found in 46 isolates (75%). The second, pattern 'E', included 8 isolates (13%), while the third, pattern 'B', included 6 isolates (10%). Pattern 'C' was found for only one isolate. All of the deer isolates were classified as pattern 'A', while cattle isolates represented all four RFLP patterns. Twenty-one isolates representing the four different BstEII-RFLP patterns were digested with PstI. Twenty isolates showed identical PstI-RFLP pattern. BstEII-RFLP patterns from Argentine cattle and deer were compared with patterns found in cattle, goat, deer, rabbit, and human isolates from Europe. The most common pattern in Argentina, pattern 'A', was identical to a less frequently occurring pattern R9 (C17) from Europe. The other Argentine patterns 'B', 'C' and 'E', were not found in the Europe. These results indicate that the distribution of M. avium subsp. paratuberculosis genotypes in the Buenos Aires province of Argentina is different from that found in Europe.

[Pure spinal leptomeningeal cysticercosis]

An adult female patient presented with an exclusively spinal leptomeningeal infestation by cysticercosis (restricted to the cauda equina), verified in surgery. The rôle of the vertebral vein system in the spread of cysticercosis larvae is discussed. A commentary on the possibility that cysticercosis of the basal cisterns may be due to ascending migration of primarily spinal cysticerel, as originally proposed by Isamat de la Riva, is stated.

Microbiology of diarrhoea in young beef and dairy calves in Argentina

Rotavirus, Cryptosporidium sp, and Salmonella spp. were investigated in the faeces of 452 diarrhoeic calves from 36 beef and 33 dairy herds. Animals surveyed were from a few days of age up to approximately 1 month of life. Enterotoxigenic Escherichia coli (ETEC) was studied in 212 calves, aged 15 days or less. The animals were from the Provinces of Buenos Aires (59% of the calves), Córdoba (18%), Santa Fe (16%), Entre Ríos (5%) and La Pampa (2%). A minimum of 4 calves were sampled on each farm. In beef calves rotavirus was excreted by 45.1% of the animals. Cryptosporidium by 30.5% and Sàlmonella serovars Arechabaleta, Livingstone, Panama and Typhimurium by 1.9%. In dairy calves Cryptosporidium was excreted by 29.6%, rotavirus by 23% and Salmonella serovar Dublin by 1.6%, ETEC was not detected in any calf. Rotavirus was the most widespread agent, detected in 32 (88.9%) beef herds and excreted by more than 50% of the calves in half of these herds. In contrast, rotavirus was only detected in 19 (57.5%) dairy herds and was excreted by more than 50% of the calves in 6 of these herds. Crytosporidium oocysts were identified in 27 (75%) beef and in 23 (69.7%) dairy farms. Salmonellosis due to serovar Dublin was associated with diarrhoea in 2 dairy herds. Concurrent infection with two or three agents occurred in 36 (8%) calves and 38 (55.1%) farms; the combination rotavirus-Cryptosporidium was found in 32 (6.9%) calves an in 33 (47.8) farms.