and M.L.; Writingreview & editing: L.K., M.C. in gel-vaccinated chicks. No differences were observed in mean antibody titres. Compared to spray, gel administration appears equally effective and less impactful on body temperature, thus supporting its application for IBV vaccination. or spp. Interactions with other respiratory or immunosuppressive viral diseases have also been documented [4]. The effective control of this highly contagious disease is essential for every type of production and is mainly achieved through rigorous biosecurity and mass vaccination [5]. Unfortunately, Z-Ile-Leu-aldehyde the efficacy of IBV vaccination is hindered by its remarkable evolutionary rate, ascribable to the frequent occurrence of both mutation and recombination events. This causes the emergence of a plethora of genetic IB variants, often found in cocirculation and coinfection and whose cross-protection is usually limited [6]. Z-Ile-Leu-aldehyde According to a phylogeny-based classification of the S1 gene sequence, a total of eight IBV genotypes are currently recognized, further divided into 36 lineages [7,8,9,10,11]. Based on which strains are circulating, several vaccination strategies can be adopted, either reliant on the administration of a homologous vaccine to the field strain or on a combination of heterologous vaccines able to provide a broader immunity, following the so-called protectotype concept [6,12]. In addition to the used vaccine strains, the conferred protection also depends on other factors related to vaccination procedures, including vaccine type, administration route and schedule [13]. Specifically, the broiler sector relies on the use of live attenuated vaccines, usually mass administered by drinking water or, more and more frequently, by spray [13]. The matter of vaccination timing is particularly debated. Multiple studies seem to suggest that the humoral immunity induced by early vaccination may be suboptimal, possibly because of interference with maternally derived antibodies (MDA), thus leaving the chicks unprotected against field viruses and favoring immuno-escape and recombination [14,15]. Despite this evidence, a clear trend towards hatchery administration has been observed recently in intensive poultry farming [16,17,18]. Moreover, even if an interval between subsequent administrations is traditionally recommended for a better immune response, likely to allow for tracheal epithelium recovery [19], the combined application of multiple vaccines at hatchery Z-Ile-Leu-aldehyde level has become the norm in many countries [16,17]. Hatchery vaccination by spray offers many advantages, such as lower labour costs and improved standardization of administration procedures and conditions compared to Z-Ile-Leu-aldehyde farm vaccination [6,17]. Several studies support its efficacy, with many vaccines being marketed as protective for the entire broiler cycle Z-Ile-Leu-aldehyde when administered at day-old [6]. On the other hand, it has been hypothesized that spray administration at the hatchery may result in a sudden drop in body temperature during a critical phase of chickens life, when the thermoregulatory system is not yet fully developed and they still act as poikilotherms [20], possibly affecting their growth and wellbeing [21]. Gel administration has recently drawn some interest as an alternative route for IBV vaccine delivery at the hatchery. Superabsorbent hydrogels are materials with a three-dimensional framework that retains stability even after absorbing large amounts of water. In the poultry sector, they have been used for a long time to supply live coccidiosis vaccines [22] and more recently probiotics and prebiotics [23]. Some studies have reported that IBV vaccination by gel allows for a proper immunization in Rabbit Polyclonal to DNA Polymerase zeta experimental conditions [23,24,25,26]. Compared to spray vaccination, it may also have the additional advantage of a lesser impact on chicks body temperature [26]. The aim of this study was to assess the applicability of IBV gel.
