Infectious bursal disease (IBD) is caused by infectious bursal disease virus (IBDV), which has a genome consisting of two segments of double-stranded linear RNA.  IBDVs have been traditionally divided into four phenotypes based on their pathogenicity and antigenicity, including classic, variant, very virulent, and attenuated IBDV.  With the emergences of divergent molecular characteristics of novel strains produced by continuous mutations and recombination, it is increasingly difficult to define new IBDV strains using the traditional descriptive classification method.  The most common classification scheme for IBDV with segmented genome is based solely on segment A, while the significance of segment B has been largely neglected.  In this study, an improved scheme for IBDV genotype classification based on the molecular characteristics of both VP2 (a viral capsid protein encoded by segment A) and VP1 (an RNA-dependent RNA polymerase protein encoded by segment B) was proposed for the first time.  In this scheme, IBDV was classified into nine genogroups of A and five genogroups of B, respectively; the genogroup A2 was further divided into four lineages.  The commonly used phenotypic classifications of classic, variant, very virulent, and attenuated IBDVs correspond to the A1B1, A2B1, A3B2, and A8B1 genotypes of the proposed classification scheme.  The novel variant IBDVs including the strains identified in this study were classified as belonging to genotype A2dB1.  The flexibility and versatility of this improved classification scheme will allow the unambiguous identification of existing and emerging IBDV strains, which will greatly facilitate molecular epidemiology studies of IBDV.

Infectious bursal disease (IBD), caused by IBD virus (IBDV), is one of the most devastating and immunosuppressive diseases of the poultry and has been a constraint on the sustainable poultry production around the globe including Pakistan.  While the disease is threatening the poultry industry, the nature of predominant strains of IBDV in Pakistan remained ill-defined.  In this study, an epidemiology survey was conducted in the main chicken-farming regions of Pakistan.  The batch of Pakistan IBDVs genes simultaneously covering both VP1 and VP2 were amplified, sequenced, and analyzed.  The unique segment-reassortant IBDVs (vv-A/Uniq-B), carrying segment A from vvIBDV and segment B from one unique ancestor, were identified as one important type of circulating strains in Pakistan.  The data also discovered the characteristic molecular features of Pakistan IBDVs, which will contribute to scientific vaccine selection and effective prevention of the disease.

The corn borer is a world-wide agricultural pest.  In this study, a high-efficiency RNAi method was explored to knock down the neuropeptide F (NPF) to determine if NPF regulates larval feeding in the Asian corn borer, Ostrinia furnacalis.  Results showed that the expression peaks of npf mRNA in both midgut and fat body are at 28 h of early 5th instar larvae.  When NPF was knocked down either by feeding dsNPF-containing artificial diet or direct dsNPF injection into the 5th instar larvae, npf expression was effectively inhibited in the midgut.  Larval feeding, body weight and development time were significantly impacted.  In contrast, the expression of the npf receptors npfr1 and npfr2 in fat body of 5th instar larvae was significantly increased by dsNPF injection.  These results indicate that NPF can be effectively knocked down in O. furnacalis, and dsNPF by injection is an effective and fast way to silence npf expression.  This study provides a critical basis for further exploration in mechanism of feeding regulation in O. furnacalis.

 

Insect neuropeptides are a group of brain neuro-regulatory factors, which plays very important roles in growth and development, molting and metamorphosis, as well as mating and reproduction.  The neuropeptide F (NPF), a multi-functional neuropeptide, is one of neuropeptides identified in numerous insect species, which plays important roles in feeding, metabolism, courtship, reproduction, aggression, ethanol sensitivity, locomotor circadian rhythms, learning and stress responses.  These roles of NPF are implemented through NPF receptors (NPFR).  The NPFR1, a G protein-coupled receptor with 7 transmembrane domains, is one of these receptors and is found to be important for NPF regulation.  The NPF usually is consisted of around 36–40 amino acid residues, but the short neuropeptide F (sNPF) consisted of 7–16 amino acid residues have also been found in some insects.  In this review, the structure and function of both NPF and sNPF in insects are discussed.