Biology subjects

Reddy, V. R. A. P.

Publications and source records attributed to Reddy, V. R. A. P..

3 recordsLinked to original sources

bioRxiv2025

Prior infection with IBDV prolonged the shedding of a mallard H3N8 influenza A virus (IAV) challenge from the oropharyngeal cavity of some chickens and increased the number of amino acid substitutions in the IAV samples

Infectious bursal disease virus (IBDV) is endemic worldwide and causes immunosuppression in chickens. We hypothesized that a previous history of IBDV in chickens would render them more susceptible to infection by influenza A viruses (IAVs) from aquatic waterfowl reservoirs. To model this, we inoculated 14 day old specific pathogen free (SPF) chickens with a low pathogenicity avian influenza (LPAI) virus strain from a mallard (A/Mallard/Alberta/156/01 (H3N8)) and compared replication and shedding between immunocompetent chickens and chickens that had immune dysregulation due to a prior IBDV infection with strain F52/70 (genogroup A1B1) at 2 days of age. The mallard IAV strain replicated in the upper respiratory tract of the chickens, and virus was shed from the oropharyngeal cavity, but there was no shedding from the cloaca, and no transmission to sentinel chickens. Replication of the mallard IAV in the chicken host was associated with amino acid substitutions in the polymerase complex and HA. IBDV infection increased the average fold change of IAV replication in the trachea of chickens, prolonged the shedding of infectious IAV from 5 to 6 days in some chickens, increased the number of amino acid substitutions detected in the IAV population from 13 to 30, and significantly increased the number of mutations per IAV sample from 2.50 (SD +/- 1.83) in the Mock/IAV group to 4.75 (SD +/- 1.81) in the IBDV/IAV group (p < 0.01). Taken together, IBDV infection prolonged the shedding of the mallard IAV in some chickens and changed IAV intra-host evolution. Author summarySpillover of IAVs from wild aquatic waterfowl into poultry populations occur frequently, which increases the risk of human infection as people have more contact with poultry than wild birds. Poultry flocks may have other co-morbidities that may influence the spread of IAV. Our data demonstrate that prior IBDV infection increased the average fold change of a mallard H3N8 LPAI virus in the trachea of inoculated chickens, prolonged the shedding of infectious IAV from the oropharyngeal cavity, and significantly increased the average number of amino acid substitutions per IAV sample. We hypothesize that IBDV infection could increase the amount of IAV shed into the environment and broaden the diversity of the IAV population shed. We conclude that controlling the spread of wild aquatic waterfowl strains of IAV in chickens should involve a holistic approach, including the control of co-morbidities and immunosuppressive diseases that could exacerbate their spread.

microbiology↗

bioRxiv2024

Reassortant strains of infectious bursal disease virus (IBDV) belonging to genogroup A3B1 predominate in British broiler chicken flocks.

As part of ongoing epidemiological surveillance for infectious bursal disease virus (IBDV), the hypervariable region (HVR) of the VP2 capsid gene encoded by segment A, and a region of the VP1 polymerase gene, encoded by segment B, were sequenced from 20 IBDV-positive bursal samples obtained in 2020 and 2021, from 16 commercial British broiler farms. Of the 16 farms, none contained very virulent (vv) strains belonging to genogroup A3B2, but 5/16 (31%) contained strains of genogroup A3B1, demonstrating birds were infected with reassortant strains containing a vv segment A and a non-vv segment B. In addition, 3/16 (19%) farms contained vaccine or classical strains belonging to genogroup A1B1, and 8/16 (50%) were co-infected with both genogroup A1B1 and A3B1 strains. Therefore, a total of 13/16 (81%) of the farms contained genogroup A3B1 reassortant viruses, the majority of which 8/13 (62%)) were found to be co-infected with genogroup A1B1 strains. Moreover, of the flocks containing reassortant strains, 5/13 (38%) had HVR mutations Q219L, G254D, D279N, and N280T, consistent with a recently described Western European clade, but 8/13 had other mutations or no mutations, demonstrating that multiple clades were present in the samples. Taken together, vv strains were not detected in the British broiler flocks we sampled, whereas reassortant strains predominated, which belonged to different clades, and were frequently found in samples that were also infected with genogroup A1B1 strains.

microbiology↗

bioRxiv2021

Birnaviridae virus factories show features of liquid-liquid phase separation, and are distinct from paracrystalline arrays of virions observed by electron microscopy

To gain more information about the nature of Birnaviridae virus factories (VFs), we used a recombinant infectious bursal disease virus (IBDV) expressing split-GFP11 tagged to the polymerase (VP1) that we have previously shown is a marker for VFs in infected cells expressing GFP1-10. We found that VFs co-localized with 5-ethynyl uridine in the presence of actinomycin D, confirming they were the site of de novo RNA synthesis, and VFs were visible in infected cells that were fixed and permeabilized with digitonin, demonstrating that they were not membrane bound. Fluorescence recovery after photobleaching (FRAP) a region of interest within the VFs occurred rapidly, recovering from approximately 25% to 87% the original intensity over 146 seconds, and VFs were dissolved by 1,6-hexanediol treatment, demonstrating they showed properties consistent with liquid-liquid phase separation. There was a lower co-localization of the VF GFP signal with the capsid protein VP2 (Manders coefficient (MC) 0.6), compared to VP3 (MC, 0.9), which prompted us to investigate the VF ultrastructure by transmission electron microscopy (TEM). In infected cells, paracrystalline arrays (PAs) of virions were observed in the cytoplasm, as well as discrete electron dense regions. Using correlative light and electron microscopy (CLEM), we observed that the electron dense regions correlated with the GFP signal of the VFs, which were distinct from the PAs. In summary, Birnaviridae VFs are sites of de novo RNA synthesis, are not bound by a membrane, show properties consistent with liquid-liquid phase separation, and are distinct from the PAs observed by TEM. ImportanceMembers of the Birnaviridae infect birds, fish and insects, and are responsible for diseases of significant economic importance to the poultry industry and aquaculture. Despite their importance, how they replicate in cells remains poorly understood. Here, we show that the Birnaviridae virus factories are not membrane bound, demonstrate properties consistent with liquid-liquid phase separation, and are distinct from the paracrystalline arrays of virions observed by transmission electron microscopy, enhancing our fundamental knowledge of virus replication that could be used to develop strategies to control disease, or optimize their therapeutic application.

microbiology↗