Studies on the ovine mast cell: heterogeneity and involvement in cutaneous inflammation

The distribution of the granule chymase Sheep Mast Cell Proteinase (SMCP) was determined in trachea, bronchus, bronchial lymph node, lung, thymus, spleen, liver, flank skin, abomasum, duodenum, jejunum, ileum, colon and mesenteric lymph node by immunohistochemistry and by ELISA using a polyclonal, affinity purified anti-SMCP antibody. The toluidine blue and SMCP-positive cell counts were closely correlated for all tissues examined (r2= 0.96, P<0.001), with the exception of skin and liver. On the basis of reactivity to the anti-SMCP antibody, two populations of ovine mast cells were identified. SMCP-positive cells (analogous to the gastrointestinal or mucosal mast cell [MMC] subset) were present in all tissues examined whereas SMCP-negative cells were present in skin (the putative ovine connective tissue mast cell [CTMC] subset) and comprised -98% of the ovine dermal mast cell population. The functional heterogeneity of the ovine dermal mast cell population was investigated in cutaneous challenge studies using the secretagogues calcium ionophore A23187 (A23187), substance P (sP) and compound 48/80 (48/80), which are known to activate CTMC subsets in other species. Although only A23187 and sP evoked an immediate weal response (P<0.05; Mann-Whitney U test [MW]), all three agents evoked dermal neutrophil influx (P<0.05; MW) with extensive mast cell degranulation (P<0.05; MW), thus identifying these agents as putative ovine dermal mast cell secretagogues. As SMCP may be released into the dermis following degranulation, its effect in ovine skin in vivo was investigated. SMCP (36pg - 36ng/50pl) evoked a dose-dependent immediate cutaneous response characterized by weal formation (maximal by three hours after injection (P<0.05; MW)) accompanied by dermal neutrophil influx (P<0.05; MW) and concomitant mast cell degranulation (P<0.05; MW). There was no subsequent delayed component to this response (24 to 72 hours). Although heat-inactivation of SMCP (64°C for 10 min; -2% residual activity) abrogated the weal response (P<0.05-P<0.01; MW), there was no effect on dermal neutrophil influx. Recombinant ovine interleukin-3 (rOv.IL-3) was shown to consistently generate a population of rOv.IL-3-dependent bone marrow-derived mast cells (rOv.IL-3 BMMC) in vitro, this cell population being subsequently used to compare functional heterogeneity in vitro to that previously determined in skin in vivo. These generated cells contained the granule-associated mediators arylsulfatase, (^-hexosaminidase and SMCP, the latter finding being consistent with an MMC phenotype. A dose-dependent effect of rOv.IL-3 on cell viability and the maximum percentage of SMCP-positive mast cells obtained was observed (P<0.05-P<0.01; Student's r-test), the latter being increased by transferring the non-adherent cell population to fresh wells or flasks at feeding. When harvested optimally at days 12 to 16 of culture, these rOv.IL-3 BMMC could be activated by sP, 48/80 and A23187 to release arylsulfatase, (3-hexosaminidase and SMCP, indicating that these cells may also possess CTMC characteristics. Thus, r.Ov.IL-3 BMMC may represent a cell population of mixed (MMC and CTMC) phenotype. SMCP failed to evoke similar mediator release in vitro, in contrast to the immediate cutaneous response observed in vivo. One action of SMCP may therefore be to activate vascular endothelium, thereby promoting increased vascular permeability and subsequent dermal neutrophil influx

The efficacy of a multivalent calicivirus, herpesvirus and parvovirus vaccine and a rabies vaccine is not affected when administered in combination

The results of a serological study examining the antibody responses generated in cats following administration of a trivalent feline vaccine (feline calicivirus [FCV], feline herpesvirus [FHV] and feline panleucopaenia virus [FPV]; Versifel CVR) in combination with an inactivated rabies vaccine, in compliance with European Pharmacopoeia requirements to support new product registrations, are presented. Nine week old cats were allocated to one of three groups, 10 cats per group. Group 1 received the CVR vaccine on days 0 and 21, group 2 received the rabies vaccine on day 21 and group 3 received the CVR vaccine on day 0 and the CVR vaccine reconstituted with the rabies vaccine (i.e., administered simultaneously) on day 21. Blood samples were collected from each animal, on days 0, 21, 28, 35, 42 and 49; and antibody titres determined using haemagglutination inhibition assay or virus neutralisation test. FHV and FPV antibody responses in the group 3 combination administration were considered non-inferior to the responses in the group 1 CVR-only at all time points (days 28, 35, 42 and 49). However for FCV, group 3 was considered non-inferior to the responses in group 1 on days 28, 35 and 42; but not on day 49. For rabies, group 3 was only considered non-inferior to the responses in group 2 on day 49; an apparent inferiority was observed on days 28, 35 and 42. However, in all cases cats that received the combination administration seroconverted with antibody titres at a magnitude shown in other studies to be protective against virulent challenge, and also at a titre deemed adequate by the European Pharmacopeia monograph 04/2013:0451 (Rabies vaccine [inactivated] for Veterinary use). In conclusion, the data show that combining these two separate vaccines in one administration has limited impact on their ability to generate serological responses, and that these responses are still of a magnitude previously demonstrated to be protective

The administration of a single dose of a multivalent (DHPPiL4R) vaccine prevents clinical signs and mortality following virulent challenge with canine distemper virus, canine adenovirus or canine parvovirus

AbstractFour challenge studies following vaccination of dogs with a multivalent vaccine containing canine parvovirus (CPV-2b), adenovirus (CAV-1/-2) and distemper (CDV) are described. Six week old puppies received a single vaccination while non-vaccinated control dogs received water. In each respective trial, groups of dogs were challenged 21days after vaccination with heterologous viral isolates. Clinical observations, rectal temperature measurements, and blood and swab samples for analysis were collected throughout the study.Dogs in all studies had normal temperatures and general health up to challenge. Clinical signs of infection and temperatures outside the normal range were observed in non-vaccinated dogs challenged with CDV, CPV, CAV-1 and CAV-2; vaccinated dogs remained clinically normal after challenge. All dogs were sero-negative prior to vaccination, non-vaccinated dogs remaining negative until challenge. Vaccinated dogs all sero-converted by 21days after vaccination, with further increases seen after challenge. Non-vaccinated dogs sero-converted following challenge with CPV or CAV-2; no final blood samples were taken in the CDV and CAV-1 studies. Rectal swab analysis showed prevention of CPV shedding in vaccinated compared to non-vaccinated dogs, and nasal swab analysis following CAV-2 challenge showed longer duration and higher amount of viral shedding for non-vaccinated dogs.In conclusion, we demonstrated that a single administration of a minimum titre, multivalent vaccine to dogs of six weeks of age is efficacious and prevents clinical signs and mortality caused by CAV-1 and CDV; prevents clinical signs and significantly reduces virus shedding caused by CAV-2; and prevents clinical signs, leucopoenia and viral excretion caused by CPV

Difficulties in demonstrating long term immunity in FeLV vaccinated cats due to increasing age-related resistance to infection

Abstract Background Feline leukaemia virus (FeLV) is a pathogen causing fatal illness in cats worldwide, and as such there is a high demand for products to protect against disease. The duration of immunity provided by an inactivated FeLV vaccine, Versifel FeLV, when administered to cats of the target age was determined. Kittens received two vaccinations when aged 7 to 9 weeks old, and were subsequently challenged up to 36 months later with the FeLV-A Glasgow isolate. Results In all studies, all of the younger aged control kittens showed persistent FeLV p27 antigenaemia confirming that the challenge virus was severe and efficacious. In contrast, the control cats did not show the required level of persistent antigenaemia, with a maximum of 45% cats affected in the middle duration study and only 10% in the longer study. However, apart from one animal in the short duration study, all of the cats vaccinated with Versifel FeLV were negative for persistent antigenaemia and can be considered treatment successes. Conclusion In conclusion, we have shown that although age-related resistance to infection with a virulent FeLV challenge is evident from as early as 10 months of age, vaccination with Versifel FeLV may aid in the protection of cats from FeLV related disease up to three years after primary vaccination as kittens.</p