Pigeon circovirus (PiCV) is the most recurrent virus diagnosed in pigeons and is among the major causative agents of young pigeon disease syndrome (YPDS). Due to the lack of an established laboratory protocol for PiCV cultivation, development of prophylaxis is hampered. Alternatively, virus-like particles (VLPs), which closely resemble native viruses but lack the viral genetic material, can be generated using a wide range of expression systems and are shown to have strong immunogenicity. Therefore, the use of VLPs provides a promising prospect for vaccine development. In this study, transfected human embryonic kidney (HEK-293) cells, a mammalian expression system, were used to express the PiCV capsid protein (Cap), which is a major component of PiCV and believed to contain antibody epitopes, to obtain self-assembled VLPs. The VLPs were observed to have a spherical morphology with diameters ranging from 12 to 26 nm. Subcutaneous immunization of pigeons with 100 µg PiCV rCap-VLPs supplemented with water-in-oil-in-water (W/O/W) adjuvant induced specific antibodies against PiCV. Observations of the cytokine expression and T-cell proliferation levels in spleen samples showed significantly higher T-cell proliferation and IFN- γ expression in pigeons immunized with VLPs compared to the controls (p < 0.05). Experimentally infected pigeons that were vaccinated with VLPs also showed no detectable viral titer. The results of the current study demonstrated the potential use of PiCV rCap-VLPs as an effective vaccine candidate against PiCV.

The pigeon circovirus (PiCV), first described in the literature in the early 1990s, is considered one of the most important infectious agents affecting pigeon health. Thirty years after its discovery, the current review has employed bibliometric strategies to map the entire accessible PiCV-related research corpus with the aim of understanding its present research landscape, particularly in consideration of its historical context. Subsequently, developments, current knowledge, and important updates were provided. Additionally, this review also provides a textual analysis examining the relationship between PiCV and the young pigeon disease syndrome (YPDS), as described and propagated in the literature. Our examination revealed that usages of the term ‘YPDS’ in the literature are characterizations that are diverse in range, and neither standard nor equivalent. Guided by our understanding of the PiCV research corpus, a conceptualization of PiCV diseases was also presented in this review. Proposed definitions and diagnostic criteria for PiCV subclinical infection (PiCV-SI) and PiCV systemic disease (PiCV-SD) were also provided. Lastly, knowledge gaps and open research questions relevant to future PiCV-related studies were identified and discussed.

Pigeon racing’s recent upturn in popularity can be attributed in part to the huge prize money involved in these competitions. As such, methods to select pigeons with desirable genetic characteristics for racing or for selective breeding have also been gaining more interest. Polymerase chain reaction—restriction fragment length polymorphism (PCR-RFLP) for genotyping-specific genes is one of the most commonly used molecular techniques, which can be costly, laborious and time consuming. The present study reports the development of an alternative genotyping method that employs Kompetitive Allele Specific Polymerase Chain Reaction (KASP) technology with specifically designed primers to detect previously reported racing performance-associated polymorphisms within the LDHA, MTYCB, and DRD4 genes. To validate, KASP assays and PCR-RFLP assays results from 107 samples genotyped for each of the genes were compared and the results showed perfect (100%) agreement of both methods. The developed KASP assays present an alternative rapid, reliable, and cost-effective method to identify polymorphisms in pigeons.

No abstract

TRICHODERMA-INDUCED SYSTEMIC RESISTANCE AGAINST THE SCALE INSECT (UNASPIS MABILIS LIT & BARBECHO) IN LANZONES (LANSIUM DOMESTICUM CORR.) SUMMARY Unaspis mabilis infestations have been causing huge economic losses to the lanzones industry in the Philippines since 2009. This study, therefore, seeks to determine the use of Trichoderma as myco-biocontrol agent to increase lanzones (Lansium domesticum) defense and resistance against this insect. Two experiments were designed to test for the protective and rescuing capacity of Trichoderma inoculation against the insect pest. For both experiments, leaf area, leaf count, scale insect populations and densities were observed over time. Additionally, to assess the phytochemical response of the plants, the concentrations of jasmonic acid, salicylic acid, total phenol content, and total flavonoid content were also measured in the rescuing capacity experiment. Results indicated that the plants inoculated with Trichoderma were performing better, showing lower populations and slower growth rate of the insect, than the uninoculated plants for both the protective and rescuing capacity experiments. Phytochemical analysis revealed the presence of tannins, phlobatannins, flavonoids, steroids, glycosides, and alkaloids in the leaves of L. domesticum. Total phenols and flavonoids showed decreasing concentrations as the infestation progressed, while the concentrations of jasmonic acid and salicylic acid in scaleinsect-infested plants were found to be influenced by the inoculation of the plants with Trichoderma.

Soft rot caused by Pectobacterium spp. is responsible for significant losses in vegetable production worldwide. Methods for the effective control of this disease are limited and are primarily based on good agricultural practices. The use of phages as biocontrol agents appears to be a promising alternative to combat phytopathogens. In this study, we investigated the efficacy of lytic phages against soft rot caused by Pectobacterium carotovorum subsp. carotovorum. Designated as PPc_A3, PPc_D1, and PPc_J3, three bacteriophage isolates, which were recovered from symptomatic tissues and environmental samples, were observed to effectively lyse P. carotovorum subsp. carotovorum. PPc_A3 belongs to the Podoviridae family, while phages PPc_D1 and PPc_J3 belong to the Myoviridae family based on the morphological features of the virions as observed using transmission electron microscopy. The optimal multiplicity of infection (MOI) differed greatly among the three phages. All survived incubations at 30°C, 40°C and 50°C and at pH ranging from 3.0 to 9.0, but were all inactivated at 60°C and at pH 12. Both monophage and cocktail preparations were effective in inhibiting the growth of P. carotovorum subsp. carotovorum in in vitro challenge tests. In the semi-in planta assays, monophage treatments resulted in significant reduction of tissue maceration in potato slices, while treatment with cocktail preparations completely inhibited the development of soft rot disease. Overall, these results demonstrate the efficacy of cocktail formulations of phages PPc_A3, PPc_D1, and PPc_J3 for the biocontrol of soft rot disease caused by P. carotovorum subsp. carotovorum.