Biology subjects

Preston, S. G.

Publications and source records attributed to Preston, S. G..

4 recordsLinked to original sources

bioRxiv2024

Immunisation of chickens with inactivated and/or infectious H9N2 avian influenza virus leads to differential immune B cell repertoire development

Avian influenza viruses (AIVs) are a major economic burden to the poultry industry, and pose serious zoonotic risk, with human infections being reported every year. To date, the vaccination of birds remains the most important method for the prevention and control of AIV outbreaks. Most national vaccination strategies against AIV infection use whole-virus inactivated vaccines, which predominantly trigger a systemic antibody-mediated immune response. There are currently no studies that have examined the antibody repertoire of birds that were infected with and/or vaccinated against AIV. To this end, we evaluate the changes in the H9N2-specific IgM and IgY repertoires in chickens subjected to vaccination(s) and/or infectious challenge. We show that a large proportion of the IgM and IgY clones were shared across multiple individuals, and these public clonal responses are dependent on both the immunisation status of the birds and the specific tissue that was examined. Furthermore, analysis reveals specific clonal expansions which are restricted to particular H9N2 immunisation regimes. These results indicate that both the nature and number of immunisations are important drivers of the antibody responses and repertoire profiles in chickens following H9N2 antigenic stimulation. We discuss how the repertoire biology of avian B cell responses may affect the success of AIV vaccination in chickens, in particular the implications of public versus private clonal selection.

immunology↗

bioRxiv2022

High resolution parallel sequencing reveals multi-strain Campylobacter in broiler chicken flocks testing 'negative' by conventional culture methods: implications for control of Campylobacter infection.

Contaminated chicken meat is a major source of human Campylobacteriosis and rates of infection remain high, despite efforts to limit the colonisation of broiler (meat) chicken flocks on farms. Using conventional testing methods of culture or qPCR, Campylobacter is typically detected amongst broiler flocks from 3 weeks of age, leading to the assumption that infection is introduced horizontally into chicken rearing houses at this time. In this study, we use parallel sequencing of a fragment of the Campylobacter outer membrane protein, encoded by the porA gene, to test for presence of Campylobacter DNA amongst fresh faecal samples collected from broiler flocks aged 23-28 days. Campylobacter DNA was detected in all of the 290 samples tested using the porA target, and in 48% of samples using 16S bacterial profiling, irrespective of whether or not Campylobacter could be detected using conventional qPCR thresholds. A single porAf2 variant was predominant amongst flocks that would be determined to be Campylobacter positive by conventional means, but a diverse pattern was seen amongst flocks that were Campylobacter negative. The ability to routinely detect low levels of Campylobacter amongst broiler flocks at a much earlier age than would conventionally be identified requires a re-examination of how and when biosecurity measures are best applied for live birds. In addition, it may be useful to investigate why single Campylobacter variants proliferate in some broiler flocks and not others.

microbiology↗

bioRxiv2020

Alpha globin variation in the long-tailed macaque suggests malaria selection

Human haemoglobin variants, such as sickle, confer protection against death from malaria; consequently, frequencies of such variants are often greatly elevated in humans from malaria endemic regions. Among non-human primates, the long-tailed macaque, Macaca fascicularis, also displays substantial haemoglobin variation. Almost all M. fascicularis haemoglobin variation is in the alpha globin chain, encoded by two linked genes: HBA1 and HBA2. We demonstrate that alpha globin variation in M. fascicularis correlates with the strength of malaria selection. We identify a range of missense mutations in M. fascicularis alpha globin and demonstrate that some of these exhibit a striking HBA1 or HBA2 specificity, a pattern consistent with computational simulations of selection on genes exhibiting copy number variation. We propose that M. fascicularis accumulated amino acid substitutions in its alpha globin genes under malaria selection, in a process that closely mirrors, but does not entirely converge with, human malaria adaptation.

evolutionary biology↗

bioRxiv2020

Deep sequencing reveals Campylobacter in commercial meat chickens less than 8 days old.

Campylobacter from contaminated poultry meat is a major source of human gastroenteritis worldwide. To date, attempts to control this zoonotic infection with on-farm biosecurity measures have been inconsistent. A cornerstone of these efforts has been the detection of chicken infection with microbiological culture, which typically does not occur until birds are at least 21 days old. Using molecular methods for detecting Campylobacter presence, 16S microbiome analysis and deep sequencing of the Campylobacter porA gene, Campylobacter can be identified at very low levels in most or all flocks fewer than 8 days old. These young chicks exhibit a much greater diversity of porA types than older birds testing positive for Campylobacter by culture or qPCR. This suggests that, as the bacteria multiply sufficiently to be detected by culture methods, one or two strains, as indicated by porA type, dominate the infection. The findings that (i) most young chicks carry some Campylobacter and (ii) not all flocks become Campylobacter positive by culture, suggests that efforts to control infection should concentrate on how to maintain Campylobacter at low levels by the prevention of the overgrowth of single strains, which ultimately leads to the contamination of food.

microbiology↗