Understanding Age-Related Longitudinal Dynamics in Abundance and Diversity of Dominant Culturable Gut Lactic Acid Bacteria in Pastured Goats.

Understanding gut lactic acid bacteria (LAB) in healthy hosts is an important first step in selecting potential probiotic species. To understand the dynamics of LAB in healthy goats, a cohort of thirty-seven healthy new-born goat kids was studied over a ten-month period. Total LAB was quantified using SYBR green qPCR. Seven hundred LAB isolates were characterized using microscopy, M13 RAPD genotyping and 16S rDNA sequencing. The highest and lowest LAB counts were detected at one week and ten months of age, respectively. Diverse LAB species were detected, whose identity and prevalence varied with age. The main isolates belonged to Limosilactobacillus reuteri, Limosilactibacillus fermentum, Lactobacillus johnsonni, Ligilactobacillus murinus, Ligilactobacillus salivarius, Limosilactobacillus mucosae, Lactiplantibacillus plantarum, Ligilactobacillus agilis, Lactobacillus acidophilus/amyolovolus, Pediococcus spp. and Enterococcus spp. Uniquely, L. reuteri and Pediococcus spp. were most common in pre- and peri-weaned goats, while Lactobacillus mucosae and Enterococcus spp. were predominant in goats one month and older. Based on RAPD genotyping, L. reuteri had the highest genotypic diversity, with age being a factor on the genotypes detected. This data may be relevant in the selection of age-specific probiotics for goats. The findings may also have broader implications by highlighting age as a factor for consideration in probiotic bacteria selection in other animal hosts.

Combined infectious bronchitis virus Arkansas and Massachusetts serotype vaccination suppresses replication of Arkansas vaccine virus.

Polyvalent infectious bronchitis virus vaccination is common worldwide. The possibility of vaccine interference after simultaneous combined vaccination with Arkansas (Ark) and Massachusetts (Mass)-type vaccines was evaluated in an effort to explain the high prevalence of Ark-type infectious bronchitis virus in vaccinated chickens. Chickens ocularly vaccinated with combinations of Ark and Mass showed predominance of Mass vaccine virus before 9 days post-vaccination (DPV) in tears. Even when Mass and Ark vaccines were inoculated into separate eyes, Mass vaccine virus was able to outcompete Ark vaccine virus. Although Mass vaccine virus apparently had a replication advantage over Ark vaccine in ocular tissues, Ark vaccine virus appeared to have an advantage in spreading to and/or replicating in the trachea. When chickens vaccinated with Ark or Mass vaccine were housed together, Mass vaccine virus was able to spread to Ark-vaccinated chickens, but the Ark vaccine was not detected in Mass-vaccinated chickens. Only Mass vaccine was detected in tears of sentinel birds introduced into groups receiving both vaccines. Furthermore, Ark vaccine virus RNA was not detectable until 10 DPV in most tear samples from chickens vaccinated with both Ark and Mass vaccines at varying Ark vaccine doses, while high concentrations of Mass virus RNA were detectable at 3-7 DPV. In contrast, Ark vaccine virus replicated effectively early after vaccination in chickens vaccinated with Ark vaccine alone. The different replication dynamics of Ark and Mass viruses in chickens vaccinated with combined vaccines did not result in reduced protection against Ark challenge at 21 DPV. Further studies are needed to clarify if the viral interference detected determines differences in protection against challenge at other time points after vaccination.

Comparison of vaccine subpopulation selection, viral loads, vaccine virus persistence in trachea and cloaca, and mucosal antibody responses after vaccination with two different Arkansas Delmarva Poultry Industry -derived infectious bronchitis virus vaccines.

Factors responsible for the persistence of Arkansas Delmarva Poultry Industry (ArkDPI)-derived infectious bronchitis vaccines in commercial flocks and the high frequency of isolation of ArkDPI-type infectious bronchitis viruses in respiratory cases are still unclear. We compared dynamics of vaccine viral subpopulations, viral loads, persistence in trachea and cloaca, and the magnitude of infectious bronchitis virus (1BV)-specific antibody induction after vaccination with two commercial ArkDPI-derived Arkansas (Ark) serotype vaccines. One of the vaccines (coded vaccine B) produced significantly higher vaccine virus heterogeneity in vaccinated chickens than the other vaccine (coded A). Chickens vaccinated with vaccine B had significantly higher viral loads in tears at 5 days postvaccination (DPV) than those vaccinated with vaccine A. Vaccine B also induced a significantly higher lachrymal immunoglobulin M response at 11 DPV, an earlier peak of IBV-specific lachrymal immunoglobulin A, and higher serum antibodies than vaccine A. In addition, a significantly higher proportion of birds vaccinated with vaccine B had vaccine virus detected in the trachea at 20 DPV than those vaccinated with vaccine A. Furthermore, the virus detected at 20 DPV in most of the chickens vaccinated with vaccine B was a single specific subpopulation (subpopulation 4) selected from multiple vaccine subpopulations detected earlier at 5 and 7 DPV in the same chickens. On the other hand, a higher proportion of chickens vaccinated with vaccine A had virus detected in cloacal swabs at 20 DPV. Thus we found differences in mucosal antibody induction and selection and persistence of vaccine viruses between two ArkDPI-derived vaccines from different manufacturers. The higher vaccine virus heterogeneity observed in chickens vaccinated with vaccine B compared with those vaccinated with vaccine A may be responsible for these differences. Thus the high frequency of Ark IBV viruses in the field may be due to the inherent ability of some ArkDPI-derived vaccine viruses to be selected and persist in vaccinated chickens. Vaccine virus persistence may offer genetic material for recombination or may undergo mutations with the potential to result in increased virulence.

The proportion of specific viral subpopulations in attenuated Arkansas Delmarva poultry industry infectious bronchitis vaccines influences vaccination outcome.

We investigated the significance of differing proportions of specific subpopulations among commercial Arkansas (Ark) Delmarva poultry industry (DPI) vaccines with regard to vaccination outcome. Two ArkDPI-derived vaccines that contain a higher proportion of viruses with S1 genes that become selected during replication in chickens exhibited more rapid establishment of those selected subpopulations in chickens, produced significantly higher viral loads in tears, and induced higher antibody responses compared with two other ArkDPI vaccines with lower proportions of viruses that become selected in chickens. The presence of higher proportions of selected subpopulations was also associated with a significantly higher incidence of respiratory signs early after vaccination and in some cases more severe tracheal lesions. However, one of the ArkDPI-derived vaccines with a lower proportion of selected subpopulations, despite producing a lower viral load in tears, also induced a higher incidence of respiratory signs later after vaccination and more severe tracheal lesions. Furthermore, one of the ArkDPI-derived vaccines with a higher proportion of selected subpopulations, despite producing a higher viral loads in tears, resulted in less severe tracheal damage. These discrepancies suggest that infectious bronchitis virus (IBV) load in tears may not always predict degree of tracheal damage and that phenotypic characteristics other than S1 may also be involved in severity of vaccine reactions following ArkDPI vaccine administration. We observed lower antibody responses to the vaccines that produced lower viral loads, which might contribute to the persistence of Ark serotype IBV vaccines observed in commercial flocks.