Effective production of recombinant Δ60VP1 chicken anemia virus protein in Escherichia coli and its application to a serodiagnostic indirect ELISA

Paper-based electrochemical immunosensor for highly sensitive detection of chicken anemia virus

Chicken anemia virus (CAV) is one of the primary causes of morbidity and mortality in young chickens. Given the importance of timely detection for maintaining livestock quality, there is a pressing need for rapid and field-deployable diagnostic tools. This study introduces a highly sensitive paper-based electrochemical immunosensor (PEI) for the detection of the 60 amino acid N-terminally truncated viral protein 1 (Δ60VP1), a derivative of the CAV capsid (VP1). A custom antibody was produced for precise immunoassay detection, with results obtainable within 30 min using Square Wave Voltammetry (SWV). The underlying mechanism involves an immunocomplex in the sample zone that hinders the electron transfer of redox species, thereby reducing the current signal in proportion to the Δ60VP1 concentration. Under optimal conditions, the detection linearity for Δ60VP1 ranged from 80 to 2500 ng/mL, with a limit of detection (LoD) of 25 ng/mL. This device was then successfully applied to detect VP1 in 29 chicken serum samples, achieving 91.6% sensitivity and 94.1% selectivity. In conclusion, the PEI device presents a promising solution for rapid, sensitive, and disposable detection of chicken pathogens, potentially revolutionizing productivity and quality assurance in chicken farming.

Development of a lateral flow assay for rapid and accurate detection of chicken anemia virus

Significant challenges to poultry health are posed by chicken anemia virus (CAV), which induces immunosuppression and causes increased susceptibility to secondary infections. The effective management and containment of CAV within poultry stocks require precise and prompt diagnosis. However, a deficiency persists in the availability of low-cost, rapid, and portable CAV detection devices. In this study, an immunochromatographic lateral-flow test strip-based assay was developed for CAV detection using in-house generated monoclonal antibodies (MABs) against CAV viral protein 1 (VP1). The recombinant truncated VP1 protein (Δ60VP1), with amino acid residues 1 to 60 of the native protein deleted, was produced via a prokaryotic expression system and utilized for immunizing BALB/c mice. Subsequently, high-affinity MABs against Δ60VP1 were generated and screened using conventional hybridoma technology combined with serial dilution assays. Two MABs, MAB1, and MAB3, both binding to distinct epitopes of Δ60VP1, were selected for the development of a lateral-flow assay. Sensitivity analysis demonstrated that the Δ60VP1 antigen could be detected by our homemade lateral-flow assay at concentrations as low as 625 ng/mL, and this sensitivity was maintained for at least 6 mo. The assay exhibited high specificity, as evidenced by its lack of reactivity with surrogate recombinant proteins and the absence of cross-reactivity with other chicken viruses and viral antigens. Comparative analysis with quantitative PCR data demonstrated substantial agreement, with a Kappa coefficient of 0.66, utilizing a sample set comprising 305 clinical chicken serum samples. In conclusion, the first lateral-flow assay for CAV detection was developed in this study, utilizing 2 specific anti-VP1 MABs. It is characterized by simplicity, rapidity, sensitivity, and specificity.

Research Note: A novel peptide-based ELISA for efficient detection of antibody against chicken infectious anemia virus

Chicken infectious anemia virus (CIAV) is the pathogen of chicken infectious anemia. Currently, due to the lack of effective diagnostics technology and prevention approach, CIAV has spread globally and caused huge economic losses to poultry industry. In this study, a novel peptide-based ELISA (pELISA) for efficient detection of antibody against CIAV was developed. The peptide (25CRLRRRYKFRHRRRQRYRRRAF45) used in pELISA was highly conserved in VP1 protein of different CIAV isolates. The specificity and reproducibility showed that the pELISA only reacted with sera against CIAV, not with sera against other pathogens tested, and the CV of the intra-/inter-assay of the pELISA was 6.8 to 9.22%. Moreover, the comparison assay using 56 clinical samples showed that the positive rate of the pELISA and the commercial ELISA kit (IDEXX) was 85.7 and 80.4%, respectively. The pELISA generated here provides a rapid and efficient serological detection method for diagnosis of CIAV infection and evaluation of the efficacy of CIAV vaccination.

Serological investigation of Gyrovirus homsa1 infections in chickens in China

BACKGROUND

Gyrovirus homsa1 (GyH1) (also known as Gyrovirus 3, GyV3) is a non-enveloped, small, single-stranded DNA virus, which was first identified in children with acute diarrhea, and was subsequently detected in marketed chickens, broilers with transmissible viral proventriculitis (TVP), and mammals. GyH1 is a pathogenic virus in chickens, causing aplastic anemia, immunosuppression, and multisystem damage. However, the seroepidemiology of GyH1 infection in chickens remains unclear. Here, we investigated the seroprevalence of GyH1 in chickens by ELISA to reveal the endemic status of GyH1 in China.

RESULTS

An indirect ELISA with high sensitivity and specificity was developed for investigation of seroepidemiology of GyH1 in chickens in China. The seropositive rate of GyH1 ranged from 0.6% to 7.7% in thirteen provinces, and ranged from 4.1% to 8.1% in eight species chickens. The seropositive rate of GyH1 in broiler breeders was significantly higher than that of in layers. There was a negative correlation between seropositive rate and age of chickens. The highest and lowest seropositive rate were present in chickens at 30-60 days and over 180 days, respectively.

CONCLUSIONS

The seroepidemiological investigation results demonstrated that natural GyH1 infection is widespread in chickens in China. Different species showed different susceptibility for GyH1. Aged chickens showed obvious age-resistance to GyH1. GyH1 has shown a high risk to the poultry industry and should be highly concerned.

Molecular Epidemiology and Pathogenic Characterization of Novel Chicken Infectious Anemia Viruses in Henan Province of China

Chicken infectious anemia (CIA) is an immunosuppressive disease caused by the chicken infectious anemia virus (CIAV) resulting in heavy economic losses once an outbreak is established. This study conducted a systematic analysis of the epidemiology and pathology of CIA in Henan province, China. A total of 437 clinical tissue samples and 120 poultry disease-related live attenuated vaccines were collected during 2017–2020; of which 45 were positive for CIAV nucleic acid, with a positive rate of 8.08%. Our results showed that genome sequence similarity among a total of 12 CIAV isolates was high, and ranged from 97.1 to 99.3%, and their similarity to the vaccine strains Cux-1 and Del-Ros ranged from 97.8 to 98.6%. However, There were mutations in the locus of the major capsid proteins VP1, VP2, and VP3 among all isolates. The subsequent sequence analysis indicated that the isolates of HN-4 and HN-8 showed genetic recombination and follow up animal experiments revealed that HN-4 might be a pathogenic strain. Our results reveal that both field infection and non-CIAV vaccines contamination promote the epidemiology of CIAV in China and some dominant epidemic viruses have undergone recombination and evolution. This study provides important information to help with the prevention and control of CIAV in the poultry industry.