Biology subjects

Brookes, S. M.

Publications and source records attributed to Brookes, S. M..

6 recordsLinked to original sources

bioRxiv2025

Infection of point-of-lay hens to assess the sequential events during H7N7 high-pathogenicity avian influenza emergence at a layer premises

H7N7 low-pathogenicity avian influenza virus (H7N7-LPAIV) incursions have preceded emergence of H7N7 high-pathogenicity (HP)AIV at several European layer hen outbreaks. Evidence from a UK layer H7N7-HPAIV (2008) outbreak informed in vivo modelling of sequential events, beginning with H7N7-LPAIV precursor incursion. Three groups of 17-week-old (point-of-lay) hens were inoculated with three precursor H7N7-LPAIV candidates which possessed: Group 1 - the classic LPAIV single-basic cleavage site (CS) (H7N7-SBCS); Group 2 - the dibasic CS (H7N7-DBCS) discovered at the outbreak (both represented direct H7N7-HPAIV (2008) precursors); Group 3 - a related European H7N7-LPAIV (2008) which possessed a DBCS within its haemagglutinin (HA) gene which was highly-conserved with the HA of the UK (2008) outbreak H7N7-HPAIV, but its other genetic segments differed. In Groups 1-3, initial H7N7-LPAIV exposure caused limited viral shedding, restricted H7-antibody responses and no deaths, by 14-days post-inoculation (dpi). H7N7-HPAIV challenge of all groups (n=8 per challenge group, including AIV-naive hens in Group 4) followed at 14 dpi. Prior H7N7-LPAIV inoculation protected against mortality due to H7N7-HPAIV challenge to varying degrees, with eight (100%), seven (87.5%), six (75%) and three (37.5%) survivors in Groups 1-4, respectively, by study-end (14-days post-challenge), when all 24 survivors had strongly seroconverted. Among challenge survivors belonging to Groups 1-3, 20/21 (95%) shed H7N7-HP, indicating that immunity acquired during initial H7N7-LPAIV exposure did not arrest H7N7-HPAIV replication. Despite prior H7N7-LPAIV incursion which elicited additional clinical protection against H7N7-HPAIV challenge, we showed how an emergent H7N7-HPAIV may represent a source for onward spread and further HPAIV outbreaks.

microbiology↗

bioRxiv2024

Validation of Optimized Methods for Avian Influenza Virus Isolation in Specific Pathogen-Free Embryonated Fowl Eggs

The internationally recognised method for diagnosis of avian influenza (AI) is virus isolation (VI) in specific pathogen-free embryonated fowls eggs (EFEs). In Great Britain (GB), AI virus isolation currently involves two passages in EFEs; the first typically of two days duration followed by a second lasting up to four days meaning that premises may remain under restriction for up to six days. Shorter time lengths for AIV isolation were investigated to reduce the time that businesses remain under official restrictions to safely negate AI infection, whilst maintaining test sensitivity. Both experimental inoculations of EFEs and analyses of VI attempts from high pathogenicity (HP) AI disease incursions in GB since 2016 demonstrated that HP viruses were isolated during first passage while for low pathogenicity AI outbreaks, the second passage could be reduced to two days. Power analysis showed that the benefit of reducing the number of days outweighed the risk of missing a positive isolate. This approach will substantially reduce costs to government and industry by releasing restrictions at least two days earlier where samples are negative for viral nucleic acid. Critically, it will reduce welfare implications of housing birds under restriction and improve international standards without loss of test performance.

microbiology↗

bioRxiv2024

Evaluating the epizootic and zoonotic threat of an H7N9 low pathogenicity avian influenza virus (LPAIV) variant associated with enhanced pathogenicity in turkeys

Between 2013-2017, A/Anhui/1/13-lineage (H7N9) low pathogenicity avian influenza virus (LPAIV) was epizootic in chickens in China causing mild disease, with 616 fatal human cases. Despite poultry vaccination, H7N9 has not been eradicated. Previously we demonstrated increased pathogenesis in turkeys infected with H7N9, correlating with the emergence of the L217Q (L226Q H3 numbering) polymorphism in the haemagglutinin (HA) protein. A Q217 containing virus also arose and is now dominant in China following vaccination. We compared infection and transmission of this Q217 containing turkey-adapted (ty-ad) isolate alongside the H7N9 (L217) wild-type (wt) virus in different poultry species, and investigated the zoonotic potential in the ferret model. Both wt and ty-ad viruses demonstrated similar shedding and transmission in turkeys and chickens. However, the ty-ad virus was significantly more pathogenic than the wt virus in turkeys but not in chickens, causing 100% and 33% mortality in turkeys respectively. Expanded tissue tropism was seen for the ty-ad virus in turkeys but not chickens, yet the viral cell receptor distribution was broadly similar in visceral organs of both species. The ty-ad virus required exogenous trypsin for in vitro replication yet had increased replication in primary avian cells. Replication was comparable in mammalian cells and the ty-ad virus replicated successfully in ferrets. The L217Q polymorphism also affected antigenicity. Therefore, H7N9 infection in turkeys can generate novel variants with increased risk through altered pathogenicity and potential HA antigenic escape. These findings emphasise the requirement for enhanced surveillance and understanding of A/Anhui/1/13-lineage viruses and their risk to different species.

microbiology↗

bioRxiv2022

The origin of internal genes contributes to the replication and transmission fitness of H7N9 avian influenza virus

H9N2 avian influenza viruses (AIVs) have donated internal gene segments during the emergence of zoonotic AIVs, including H7N9. We used reverse genetics to generate three reassortant viruses (2:6 H7N9) which contained the Haemagglutinin and Neuraminidase from Anhui/13 (H7N9) and the six internal gene segments from H9N2 AIVs of G1-like or BJ94-like lineages enzootic in different geographic regions in Asia. Infection of chickens with the 2:6 H7N9 containing internal gene segments from G1-like H9N2 conferred attenuation in vivo, with lower shedding and reduced transmission to contact chickens. However, possession of BJ94-like H9N2 internal gene segments resulted in more rapid transmission and significantly elevated cloacal shedding compared to the parental Anhui/13 H7N9. In vitro analysis also showed that the 2:6 H7N9 having BJ94-like internal genes had significantly increased replication compared to the Anhui/13 H7N9 in chicken cells. In vivo co-infection experiments followed, where chickens were co-infected with pairs of Anhui/13 H7N9 and one of each of the three 2:6 H7N9 reassortants. During ensuing transmission events, the Anhui/13 H7N9 virus outcompeted 2:6 H7N9 with internal gene segments of BJ94-like or G1-like H9N2 viruses. Co-infection did lead to the emergence of novel reassortant genotypes that were transmitted to contact chickens. Some of the reassortant viruses had a greater replication in chicken and human cells compared to the progenitors. We demonstrated that the internal gene cassette determines the transmission fitness of H7N9 viruses in chickens and the reassortment events can generate novel H7N9 genotypes with increased virulence in chickens and enhanced zoonotic potential. ImportanceH9N2 avian influenza viruses (AIVs) are enzootic in poultry in different geographical regions. The internal genes of these viruses can be exchanged with other zoonotic AIVs, most notably the China-origin H7N9 that can give rise to new virus genotypes with increased veterinary, economic and public health threats to both poultry and humans. We investigated the propensity of the internal genes of H9N2 viruses (G1 or BJ94) in the generation of novel reassortant H7N9 AIVs. We observed that the internal genes of H7N9 which were derivative of BJ94-like H9N2 virus have a fitness advantage compared to those from the G1-like H9N2 viruses for efficient transmission among chickens. We also observed the generation of novel reassortant viruses during chicken transmission which infected and replicated efficiently in human cells. Therefore, such emergent reassortant genotypes may pose an elevated zoonotic threat.

microbiology↗

bioRxiv2021

Co-infection of chickens with H9N2 and H7N9 avian influenza viruses leads to emergence of reassortant H9N9 virus with increased fitness for poultry and enhanced zoonotic potential

An H7N9 low pathogenicity avian influenza virus (LPAIV) emerged through genetic reassortment between H9N2 and other LPAIVs circulating in birds in China. This virus causes inapparent clinical disease in chickens, but zoonotic transmission results in severe and fatal disease in humans. We evaluated the consequences of reassortment between the H7N9 and the contemporary H9N2 viruses of G1 lineage that are enzootic in poultry across the Indian sub-continent and the Middle East. Co-infection of chickens with these viruses resulted in emergence of novel reassortant H9N9 viruses carrying genes derived from both H9N2 and H7N9 viruses. These reassortant H9N9 viruses showed significantly increased replication fitness, enhanced pathogenicity in chicken embryos and the potential to transmit via contact among ferrets. Our study highlights that the co-circulation of H7N9 and H9N2 viruses could represent a threat for the generation of novel reassortant viruses with greater virulence in poultry and an increased zoonotic potential. O_FIG O_LINKSMALLFIG WIDTH=197 HEIGHT=200 SRC="FIGDIR/small/438444v1_ufig1.gif" ALT="Figure 1"> View larger version (96K): org.highwire.dtl.DTLVardef@1f425cborg.highwire.dtl.DTLVardef@1dd3ba2org.highwire.dtl.DTLVardef@1762348org.highwire.dtl.DTLVardef@1064cb7_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract C_FIG In BriefH9N2 viruses have a high propensity to reassort with other avian influenza viruses. We found that co-infection of chickens with H9N2 and H7N9 led to the emergence of reassortant viruses including the H9N9 subtype. Some reassortant H9N9 viruses exhibited increased replication fitness, increased pathogenicity in the chicken embryo, greater avidity for human and avian cell receptors, lower pH fusion and contact-transmission to ferrets. This study demonstrated the ability of viruses that already exist in nature to exchange genetic material, highlighting the potential emergence of viruses from these subtypes with increased zoonotic potential. There are nine H9 influenza A subtypes carrying different neuraminidase (NA) genes, including H9N9 viruses, while they are not common they do exist in nature as wildtypes (CDC). HighlightsO_LICo-infection of chickens with H7N9 and H9N2 led to emergence of reassortant H9N9 viruses C_LIO_LIReassortant H9N9 viruses had an increased replication rate in avian and human cells C_LIO_LIReassortant H9N9 viruses had a lower pH fusion and significantly higher receptor binding to 2,3 sialoglycans C_LIO_LIReassortant H9N9 replicated in ferrets at similar levels compared to H7N9 and transmitted via direct contact C_LIO_LIFerrets exposed to reassortant H9N9 by aerosol contact were also found to be seropositive C_LIO_LIExperimental simulation of events that may occur naturally with circulating viruses has demonstrated the risk of emergence of viruses with increased zoonotic potential. C_LI

microbiology↗

bioRxiv2019

Avian influenza virus (A/H3N8) with a putative mammalian-adaptive mutation found in a stranded grey seal pup (Halichoerus grypus) rescued on the Cornwall coast, UK

Avian Influenza A Viruses (IAV) in different species of seals display a spectrum of pathogenicity, from subclinical infection to mass mortality events. Here we present an investigation of avian IAV infection in a 3-4 month old Grey seal (Halichoerus grypus) pup, rescued from St Michaels Mount, Cornwall in 2017. The pup underwent medical treatment but died after two weeks; post-mortem examination and histology indicated sepsis as the cause of death. IAV NP antigen was detected by immunohistochemistry in the nasal mucosa, and sensitive real-time reverse transcription polymerase chain reaction assays detected trace amounts of viral RNA within the lower respiratory tract, suggesting that the infection may have been cleared naturally. IAV prevalence among Grey seals may therefore be underestimated. Moreover, contact with humans during the rescue raised concerns about potential zoonotic risk. Nucleotide sequencing revealed the virus to be of subtype H3N8. Combining a GISAID database BLAST search and time-scaled phylogenetic analyses, we inferred that the seal virus originated from an unsampled, locally circulating (in Northern Europe) viruses, likely from wild Anseriformes. From examining the protein alignments, we found several residue changes in the seal virus that did not occur in the bird viruses, including D701N in the PB2 segment, a rare mutation, and a hallmark of mammalian adaptation of bird viruses. IAVs of H3N8 subtype have been noted for their particular ability to cross the species barrier and cause productive infections, including historical records suggesting that they may have caused the 1889 pandemic. Therefore, infections such as the one we report here may be of interest to pandemic surveillance and risk and may help us better understand the determinants and drivers of mammalian adaptation in influenza.

microbiology↗