Entry into midgut epithelial cells is a key step in the selection of genotypes in a nucleopolyhedrovirus

An isolate of the Spodoptera frugiperda multiple nucleopolyhedrovirus comprises a stable proportion of deletion genotypes (e.g., SfNIC-C), that lack pif1 and pif2 rendering them noninfectious per os, and that survive by complementation with a complete genotype (SfNIC-B) in coinfected cells. To determine whether selection for particular ratios of complete and deletion genotypes occurs mainly during the establishment of the primary infection in insect midgut cells or during subsequent systemic infection, we examined genotype frequencies in insects that fed on OBs comprising different co-occluded mixtures of genotypes. Dramatic changes in genotype frequencies were observed between the OB inoculum and budded virus (BV) samples taken from larvae inoculated with OBs comprising 10% SfNIC-B + 90% SfNIC-C indicating that a marked reduction of SfNIC-C genotype had occurred in the insect midgut due to the immediate elimination of all OBs that originated from cells that had been infected only by SfNIC-C. In contrast, immediate changes were not observed in OBs comprising mixtures of 50% SfNIC-B + 50% SfNIC-C or those comprising 10% SfNIC-B + 90% SfNIC-C as most of the OBs in these mixtures originated from cells that had been infected by both genotypes. Subsequent changes in genotypic frequencies during five days of systemic infection were fairly small in magnitude for all genotypic mixtures. We conclude that the prevalence of defective genotypes in the SfNIC population is likely determined by a balance between host selection against OBs produced in cells infected by SfNIC-C alone and within-host selection for fast-replicating deletion genotypes. The strength of intra-host selection is likely modulated by changes in MOI during the infection period.     

Effect of willow cultivar and plant age on the melezitose content of giant willow aphid (Tuberolachnus salignus) honeydew

1. The giant willow aphid Tuberolachnus salignus is an invasive pest in New Zealand, attacking over 50 species and hybrids of willow. The aphids produce copious amounts of honeydew, which is used by other insects as a food source.
2. When foraged by honeybees, T. salignus honeydew causes honey to crystallize in the comb and affects bee health; these effects are associated with the elevated melezitose content in the honeydew. The impact of host plant-related factors on T. salignus honeydew melezitose content remains unknown.
3. This study investigated the effect of willow cultivar and plant age on the melezitose content (and that of other sugars) of T. salignus honeydew. To do so, we conducted high-performance liquid chromatography analyses of honeydew samples from 13 willow clones collected in the same season (autumn) from 1- and 2-year old plants under field conditions.
4. Melezitose was the most abundant of the measured sugars in most samples, but its content did not vary significantly with willow cultivar or plant age. By contrast, sucrose was significantly affected by both factors. Fructose and glucose were significantly impacted by willow plant age and cultivar, respectively. A significant cultivar*age interaction was observed for all sugars.
5. We recommend the selection of resistant willow cultivars and further research on potential biocontrol agents to lessen melezitose-related problems in apiculture industries.

     

Economic evaluation of the development of a phage therapy product for the control of Salmonella in poultry

Poultry products are one of the major transmission media of Salmonella enteritidis to humans. A promising alternative to reduce the load of Salmonella in poultry are bacteriophages. Elsewhere, a mixture of six bacteriophages has been used successfully, but large-scale production would be necessary to supply potential poultry market and costs analyses have not been calculated yet. For this, a powerful tool to predict production costs is bioprocess modeling coupled with economic analyses. This work aims to model the scaled-up production of a six bacteriophages mixture based on a laboratory/pilot-scale production using Biosolve Process. For the model construction, a combination of experimental and reported data was applied, in which different production alternatives and the range of 1–100% of the Colombian poultry market (at broiler's farm and slaughterhouse) were analyzed. Results indicate that the best cost-effective process configuration/scale is to use one bioreactor (156 L) for the six bacteriophages, then a 0.45 μm filtration for removal of biomass, and a 0.22 μm filtration for sterility; this to supply the 35% of the market size for broiler farms (equivalent to 210 million chickens). This configuration gives a production cost per chicken of US$ 0.02. Additionally, a sensitivity analysis and a theoretical contrast for understanding the impact that titer and recovery have on production scale determined that titer affects the most the cost and requires optimization. The present works serves as a first, and required, approach for the development of phage therapy products that are alternatives to present-day pathogens control strategies.     

Bonafide,type-specific human papillomavirus persistence among HIV-positive pregnant women: predictive value for cytological abnormalities,a longitudinal cohort study

This study investigated the rate of human papillomavirus (HPV) persistence, associated risk factors, and predictors of cytological alteration outcomes in a cohort of human immunodeficiency virus-infected pregnant women over an 18-month period. HPV was typed through L1 gene sequencing in cervical smears collected during gestation and at 12 months after delivery. Outcomes were defined as nonpersistence (clearance of the HPV in the 2nd sample), re-infection (detection of different types of HPV in the 2 samples), and type-specific HPV persistence (the same HPV type found in both samples). An unfavourable cytological outcome was considered when the second exam showed progression to squamous intraepithelial lesion or high squamous intraepithelial lesion. Ninety patients were studied. HPV DNA persistence occurred in 50% of the cases composed of type-specific persistence (30%) or re-infection (20%). A low CD4⁺T-cell count at entry was a risk factor for type-specific, re-infection, or HPV DNA persistence. The odds ratio (OR) was almost three times higher in the type-specific group when compared with the re-infection group (OR = 2.8; 95% confidence interval: 0.43-22.79). Our findings show that bonafide (type-specific) HPV persistence is a stronger predictor for the development of cytological abnormalities, highlighting the need for HPV typing as opposed to HPV DNA testing in the clinical setting.