Biology subjects

Birch, C. P. D.

Publications and source records attributed to Birch, C. P. D..

3 recordsLinked to original sources

bioRxiv2025

Immune response to co-administration of bovine tuberculosis and contraceptive vaccines in badgers (Meles meles)

Controlling bovine tuberculosis (bTB) in livestock is often hindered by the presence of a wildlife reservoir, such as the Eurasian badger in the UK and Ireland. Vaccinating badgers against bTB can reduce the severity of Mycobacterium bovis infection and potential onwards transmission to cattle, badgers and other species, thus combined with population control might provide additional benefits (and reference models). To evaluate the effects of co-administration of a bTB vaccine (BCG) and a contraceptive vaccine (GonaCon), captive badgers were injected intramuscularly with either BCG only, GonaCon only or BCG+GonaCon (phase 1). The duration of immune response to BCG vaccination and booster vaccination was also evaluated in the BCG only group over a 24-month period (phase 2). The cellular immune responses to purified protein derivatives PPDA and PPDB, used to measure the effects of BCG, did not differ significantly between the BCG only and BCG+GonaCon badgers but were significantly different between the BCG only and GonaCon only badgers. Anti-GnRH antibody titres, quantified to measure the effect of GonaCon, peaked at the first sampling point for the majority of badgers in the GonaCon only and BCG+GonaCon groups. Throughout phase 1, lasting three months post-vaccination, badgers in both GonaCon treatment groups maintained high anti-GnRH antibody titres (1:128,000 or above) that are associated with infertility in this species, with no significant difference between the two GonaCon groups. The immune responses to BCG vaccination in the BCG only badgers (phase 2) were elevated at the first sampling point, approximately three weeks after initial vaccination and booster vaccination, generally declining thereafter. The results from the current study suggest that co-administration of BCG and GonaCon do not have notable deleterious effects on either of the vaccines and that the protective effect of BCG is enhanced by booster vaccination. The protective effects afforded by both vaccines when given together, in terms of reduced disease burden or fecundity, should be determined by further studies.

immunology↗

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↗

bioRxiv2023

Difference in Differences analysis evaluates the effects of the Badger Control Policy on Bovine Tuberculosis in England

Persistent tuberculosis (TB) in cattle populations in England has been associated with an exchange of infection with badgers (Meles meles). A badger control policy (BCP) commenced in 2013. Its aim was to decrease TB in cattle by reducing the badger population available to provide a wildlife reservoir for bovine TB. Monitoring data from 52 BCP intervention areas 200-1600 km2 in size, starting over several years, were used to estimate the change in TB incidence rate in cattle herds, which was associated with time since the start of the BCP in each area. A Difference in Differences analysis addressed the non-random selection and starting sequence of the areas. Herd incidence rate of TB reduced by 56% (95% Confidence Interval 43-67%) up to the fourth year of BCP interventions, with the largest reductions in the second and third years. There was insufficient evidence to judge whether incidence rate reduced further beyond four years. These estimates are the most precise for the timing of decline in cattle TB associated with interventions primarily targeting badgers. They are within the range of previous estimates from England and Ireland. This analysis indicates the importance of reducing transmission from badgers to reduce the incidence of TB in cattle, noting that vaccination of badgers, fertility control and on farm biosecurity may also achieve this effect.

ecology↗