High-content phenotypic screening identifies novel chemistries that disrupt mosquito activity and development.

New classes of chemistries are needed to control insecticide resistant populations of mosquitoes and prevent transmission of vector-borne diseases (VBDs). Organismal screens of chemical collections have played an important role in the search for new vector insecticides and the identification of active ingredients (AIs) that cause rapid mortality of mosquitoes. Advances in image-based screening offer an opportunity to identify chemistries that operate via novel biochemical modes and investigate the range of phenotypes exhibited by mosquitoes following exposure to lethal and sub-lethal chemical dose. An automated, high throughput phenotypic screen (HTS) employing high-content imaging of first instar (L1) Aedes aegypti larvae was developed to identify chemistries associated with mortality and atypical morphological phenotypes. A pilot screen of the Library of Pharmacologically Active Compounds (LOPAC1280) identified 92 chemistries that disrupted larval activity and development, including conventional insecticides and chemistries known to modulate G protein-coupled receptors (GPCRs) and other molecular targets in mammalian systems. Secondary assay series were used to evaluate a selection of chemistries for impacts on mosquito activity, survival and development. Ritodrine hydrochloride reduced mobility of larvae but had no observable effect on survival and development of mosquitoes. High doses of metergoline suppressed larval activity and sub-lethal dose resulted in pupal mortality. Assay data support the utility of phenotypic screening and diverse entomological end-points for discovery of novel insecticidal chemical scaffolds. The insecticide discovery process must consider how multi-modal efficacy spectra contribute to vector and VBD control.

Prevalence of parvoviruses in commercial turkey flocks.

Turkey parvovirus belongs to the family Parvoviridae, subfamily Parvovirinae, Genus parvovirus. Since the initial report on turkey parvovirus in the United States appeared in 1983, there had been no further reports of parvovirus in turkeys until 2008. The aims of our study were to determine the prevalence of parvovirus in commercial turkey flocks using PCR; to determine their genetic relationship to previous strains identified in North America and Europe; and to test samples for enteric viruses by transmission electron microscopy (TEM). A total of 169 fecal samples collected from 42 turkey farms in four different states within the United States between 2000 and 2010 were examined. We found that the most frequently detected viruses by TEM were small round viruses, accounting for 52% of the examined samples; however, the PCR detected parvoviruses in 71% of the samples. The phylogenetic analysis of partial nonstructural gene sequences showed a certain degree of variability among the turkey samples tested in the study. Moreover, there was a clear dichotomy in the phylogenetic tree between chicken and turkey samples, with the exception of one turkey isolate from 2000, which clustered together with the chicken group.

Pathogenicity of turkey astroviruses in turkey embryos and poults.

The pathogenicity of turkey astrovirus 2001 (TAstV2001) and turkey astrovirus 1987 (TAstV1987) in specific-pathogen-free (SPF) turkey embryos and commercial poults was investigated. The virus shedding in poults was monitored using electron microscopy (EM) and reverse transcription-polymerase chain reaction (RT-PCR) during the 14-day experimental period. Both viruses caused enteritis and growth depression in SPF turkey embryos and poults. The TAstV2001 did not induce macroscopic or microscopic lesions in thymuses and bursas of embryos or poults. No macroscopic changes were observed in thymuses and bursas of embryos and poults inoculated with TAstV1987, and no statistically significant differences in bursa weight/ body weight ratios (P > 0.05) were detected. However, TAstV1987 infection resulted in microscopic lesions in bursas but not in thymuses of infected embryos and poults. Both TAstV2001 and TAstV1987 were shed during the whole 14-day experimental period as detected by EM and RT-PCR. These findings indicated that both TAstV1987 and TAstV2001 are etiologic agents of turkey enteritis. In addition, TAstV1987 might cause impairment of the immune system of infected poults. The pathogenicity of TAstV1987 is somewhat different from TAstV2001.