Synergistic pathogenesis of chicken infectious anemia virus and J subgroup of avian leukosis virus

Synergistic pathogenicity of vertically transmitted chicken infectious anemia virus and avian leukosis virus subgroup J coinfection in chickens

Avian leukemia virus subgroup J (ALV-J) and chicken infectious anemia virus (CIAV) can be vertically transmitted; however, the pathogenicity of vertically transmitted coinfection with these 2 pathogens has not been studied. In this study, we created a model of chick morbidity in which chicks carried either ALV-J, CIAV, or both viruses via embryo inoculation. Thereafter, we analyzed the effects of vertically transmitted coinfection with CIAV and ALV-J on the pathogenicity of ALV-J and performed a purification assay based on hatching, mortality viremia positivity, and detection of fecal ALV-p27 antigen rates, and body weight. The hatching rate of the ALV-J+CIAV group was 68.57%, lower than those of the single infection and control groups. The survival curve showed that the mortality rates of the CIAV and ALV-J coinfection groups were higher than those of the single infection and control groups. Body weight statistics showed that coinfection aggravated the 7-d growth inhibition effect. The results of ALV-p27 antigen detection in cell culture supernatants showed that the positivity rates of the ALV-J and ALV-J+CIAV groups were 100% at all ages and 0% in the control group. The results of ALV-p27 antigen detection by anal swabs showed that the positivity rates of the ALV-J group were 92.86, 90.90, 88.89, and 93.33% at all ages, and that the ALV-J p27 positivity detection rate of anal swabs was lower than that of plasma virus isolation. The immune organ index of the ALV-J+CIAV group was significantly or very significantly lower than those of the single infection and control groups. The immune organ viral load showed that coinfection with CIAV and ALV-J promoted the proliferation of ALV-J and CIAV in immune organs. Coinfection with ALV-J and CIAV reduced chicken embryo hatchability and increased chick mortality and growth inhibition relative to their respective single infections. Additionally, coinfection with ALV-J + CIAV was even more detrimental in inducing immune organ atrophy (e.g., the thymus, spleen, and bursa), and promoted individual virus replication during coinfection.

Establishment and application of a gold nanoparticle-based immunochromatographic test strip for the detection of avian leukosis virus P27 antigen in egg white samples

Avian leukemia is an infectious tumorous disease of chickens caused by subgroup A of the avian leukemia virus (ALV-A), which mainly causes long-term viremia, slow growth, immune suppression, decreased production performance, multi-tissue tumors, and even death. The infection rate of this disease is very high in chicken herds in China, causing huge economic losses to the poultry industry every year. We successfully expressed the specific antigen protein of ALV (P27) through recombinant protein technology and screened a pair of highly sensitive monoclonal antibodies (mAbs) through mouse immunity, cell fusion, and antibody pairing. Based on this pair of antibodies, we established a dual antibody sandwich ELISA and gold nanoparticle immunochromatographic strip (AuNP-ICS) detection method. In addition, the parameters of the dual antibody sandwich ELISA and AuNP-ICS were optimized under different reaction conditions, which resulted in the minimum detection limits of 0.2 ng mL-1 and 1.53 ng ml-1, respectively. Commonly available ELISA and AuNP-ICS products on the market were compared, and we found that our established immune rapid chromatography had higher sensitivity. This established AuNP-ICS had no cross-reactivity with Influenza A (H1N1), Influenza A (H9N2), respiratory syncytial virus (RSV), varicella-zoster virus (VZV), Listeria monocytogenes listeriolysin (LLO), and Staphylococcal enterotoxin SED or SEC. Finally, the established AuNP-ICS was used to analyze 35 egg samples, and the results showed 5 positive samples and 30 negative samples. The AuNP-ICS rapid detection method established by our group had good specificity, high sensitivity, and convenience, and could be applied to the clinical sample detection of ALV-A.

A review of the influence of environmental pollutants (microplastics, pesticides, antibiotics, air pollutants, viruses, bacteria) on animal viruses

Microorganisms, especially viruses, cause disease in both humans and animals. Environmental chemical pollutants including microplastics, pesticides, antibiotics sand air pollutants arisen from human activities affect both animal and human health. This review assesses the impact of chemical and biological contaminants (virus and bacteria) on viruses including its life cycle, survival, mutations, loads and titers, shedding, transmission, infection, re-assortment, interference, abundance, viral transfer between cells, and the susceptibility of the host to viruses. It summarizes the sources of environmental contaminants, interactions between contaminants and viruses, and methods used to mitigate such interactions. Overall, this review provides a perspective of environmentally co-occurring contaminants on animal viruses that would be useful for future research on virus-animal-human-ecosystem harmony studies to safeguard human and animal health.

Subclinical circulation of Chicken infectious anaemia virus- A Sero-molecular study

Chicken infectious anaemia-an important immunosuppressive viral disease of chicken-gained much attention in the recent past. Based on huge mortality and production loss observed in the fast-growing poultry sector, the present study aimed to find out the current status of the chicken infectious anaemia virus (CIAV), among chicken flocks in the Punjab state of India by sero-molecular study. The sera from the blood samples were tested for anti-CIAV antibodies by indirect ELISA and also compared with haematological parameters. DNA from sero-positive samples underwent PCR amplification, sequencing and phylogenetic analysis of the most conserved genomic region (VP3 gene) to detect viraemia in asymptomatic birds. The serological study using indirect ELISA showed a high sero-positivity of 77.27% in chicken flocks. Additionally, the present study also revealed the high molecular evidence (72.54%) of CIAV in apparently healthy birds. Genetic analysis showed that all CIAVs have conserved VP3 genes without any nucleotide substitutions, indicating presence of CIAV and its subclinical circulation among apparently healthy flocks. The wide distribution of CIAV among birds may be the reason for huge mortality and production loss. Further, it is suggested that studies be conducted to find out the co-involvement of CIAV with other immunosuppressive microbial agents and the immunosuppressive effect of CIAV in apparently healthy birds. Also, its role in vaccine failure and outbreaks of various other avian diseases needs to be explored.

Genetic characterization of chicken infectious anaemia viruses isolated in Korea and their pathogenicity in chicks

Chicken infectious anaemia virus (CIAV) causes severe anemia and immunosuppression through horizontal or vertical transmission in young chickens. Especially, vertical transmission of virus through the egg can lead to significantly economic losses due to the increased mortality in the broiler industry. Here, 28 CIAV complete sequences circulating in Korea were first characterized using the newly designed primers. Phylogenetic analysis based on the complete sequences revealed that CIAV isolates were divided into four groups, IIa (2/28, 7.1%), IIb (9/28, 32.1%), IIIa (8/28, 28.6%) and IIIb (9/28, 32.1%), and exhibited a close relationship to each other. The major groups were IIb, IIIa and IIIb, and no strains were clustered with a vaccine strain available in Korea. Also, for viral titration, we newly developed a quantitative PCR assay that is highly sensitive, reliable and simple. To investigate the pathogenicity of three major genotypes, 18R001(IIb), 08AQ017A(IIIa), and 17AD008(IIIb) isolates were challenged into one-day-old specific-pathogen-free (SPF) chicks. Each CIAV strain caused anaemia, severe growth retardation and immunosuppression in chickens regardless of CIAV genotypes. Notably, a 17AD008 strain showed stable cellular adaptability and higher virus titer in vitro as well as higher pathogenicity in vivo. Taken together, our study provides valuable information to understand molecular characterization, genetic diversity and pathogenicity of CIAV to improve management and control of CIA in poultry farm.

Avian Leukosis: Will We Be Able to Get Rid of It?

Avian leukosis viruses (ALVs) have been virtually eradicated from commercial poultry. However, some niches remain as pockets from which this group of viruses may reemerge and induce economic losses. Such is the case of fancy, hobby, backyard chickens and indigenous or native breeds, which are not as strictly inspected as commercial poultry and which have been found to harbor ALVs. In addition, the genome of both poultry and of several gamebird species contain endogenous retroviral sequences. Circumstances that support keeping up surveillance include the detection of several ALV natural recombinants between exogenous and endogenous ALV-related sequences which, combined with the well-known ability of retroviruses to mutate, facilitate the emergence of escape mutants. The subgroup most prevalent nowadays, ALV-J, has emerged as a multi-recombinant which uses a different receptor from the previously known subgroups, greatly increasing its cell tropism and pathogenicity and making it more transmissible. In this review we describe the ALVs, their different subgroups and which receptor they use to infect the cell, their routes of transmission and their presence in different bird collectivities, and the immune response against them. We analyze the different systems to control them, from vaccination to the progress made editing the bird genome to generate mutated ALV receptors or selecting certain haplotypes.

Chicken infectious anemia virus (CIAV) VP1 antagonizes type I interferon (IFN-I) production by inhibiting TBK1 phosphorylation

Chicken infectious anemia virus (CIAV) infection induces immunosuppression or subclinical immunosuppression in chickens. CIAV infection has been reported to repress type I interferon (IFN-I) expression, but the underlying mechanisms are not yet understood. Here we reported that VP1, the capsid protein of CIAV, the major immunogenic protein that triggers the production of neutralizing antibodies in chickens, inhibited type I interferon (IFN-I) expression induced by cGAS-STING signaling. We showed that VP1 inhibited TBK1 phosphorylation and down stream signal transduction, leading to the inhibition of IFN-I expression. Subsequently, we demonstrated that VP1 interacted with TBK1. Finally, we clarified that aa 120-150 in VP1 was essential for VP1 to interact with TBK1 and inhibit cGAS-STING signaling. These findings will help us further understand the pathogenesis of CIAV in chickens.

Synergistic Immunosuppression of Avian Leukosis Virus Subgroup J and Infectious Bursal Disease Virus Is Responsible for Enhanced Pathogenicity

In recent years, superinfections of avian leukosis virus subgroup J (ALV-J) and infectious bursal disease virus (IBDV) have been frequently observed in nature, which has led to the increasing virulence in infected chickens. However, the reason for the enhanced pathogenicity has remained unclear. In this study, we demonstrated an effective candidate model for studying the outcome of superinfections with ALV-J and IBDV in cells and specific-pathogen-free (SPF) chicks. Through in vitro experiments, we found that ALV-J and IBDV can establish the superinfection models and synergistically promote the expression of IL-6, IL-10, IFN-α, and IFN-γ in DF-1 and CEF cells. In vivo, the weight loss, survival rate, and histopathological observations showed that more severe pathogenicity was present in the superinfected chickens. In addition, we found that superinfections of ALV-J and IBDV synergistically increased the viral replication of the two viruses and inflammatory mediator secretions in vitro and in vivo. Moreover, by measuring the immune organ indexes and blood proportions of CD3⁺, CD4⁺, and CD8α⁺ cells, our results showed that the more severe instances of immunosuppression were observed in the superinfected chickens. In the present study, we concluded that the more severe immunosuppression induced by the synergistic viral replication of ALV-J and IBDV is responsible for the enhanced pathogenicity.

Genomic Sequence and Pathogenicity of the Chicken Anemia Virus Isolated From Chicken in Yunnan Province, China

Chicken anemia virus (CAV), which has been reported in many countries, causes severe anemia and immunosuppression in chickens. In this study, a CAV strain YN04 belonging to genotype A was first identified from infected chickens in Yunnan province, China. Moreover, the animal infection experiments further confirmed that the strain YN04 is a highly pathogenic strain, which can cause 86.67% mortality in chickens in the infection group. The mean death time of infected chickens was 13.1 days post infection (dpi). CAV infection induced severe anemia with significant decrease in packed cell volume (PCV), and serious atrophy and lesion of thymus and bursa with high viral load at 14 dpi. Besides, CAV infection caused a sharp decrease in chicken body weight and immune organ indices including the ratio of thymus or bursa to body weight at 21 dpi, which displayed the potential immunosuppression state at this stage. These findings enrich the epidemiological data on CAV and may provide information for preventing its further spread in Yunnan province, China.