Growth Performance and Clinicopathological Analyses in Lambs Repetitively Inoculated with Aluminum-Hydroxide Containing Vaccines or Aluminum-Hydroxide Only

Abstract

Aluminum (Al) hydroxide is an effective adjuvant used in sheep vaccines. However, Al-adjuvants have been implicated as potential contributors to a severe wasting syndrome in sheep—the so-called ovine autoimmune-inflammatory syndrome induced by adjuvants (ASIA syndrome). This work aimed to characterize the effects of the repetitive injection of Al-hydroxide containing products in lambs. Four flocks (Flocks 1–4; n = 21 each) kept under different conditions were studied. Three groups of seven lambs (Vaccine, Adjuvant-only, and Control) were established in each flock. Mild differences in average daily gain and fattening index were observed, indicating a reduced growth performance in Vaccine groups, likely related to short-term episodes of pyrexia and decreased daily intake. Clinical and hematological parameters remained within normal limits. Histology showed no significant differences between groups, although there was a tendency to present a higher frequency of hyperchromatic, shrunken neurons in the lumbar spinal cord in the Adjuvant-only group. Although Al-hydroxide was linked to granulomas at the injection site and behavioral changes in sheep, the results of the present experimental work indicate that injected Al-hydroxide is not enough to fully reproduce the wasting presentation of the ASIA syndrome. Other factors such as sex, breed, age, production system, diet or climate conditions could play a role.

Identification and characterization of miRNAs in spleens of sheep subjected to repetitive vaccination

“…In the same fashion as in PBMCs 14 , both aluminium hydroxide alone and commercial vaccines altered the miRNA expression, but the impact of aluminium hydroxide was smaller in the spleen. Histopathological parameters remained within normal values in splenic tissue and repetitive administration of both treatments did not cause major adverse reactions after the experiment 39 . Therefore, the transcriptomic changes observed in these and previous results reflect a normal immune response to vaccine adjuvants.…”

Inflammation and Autophagy: A Convergent Point between Autism Spectrum Disorder (ASD)-Related Genetic and Environmental Factors: Focus on Aluminum Adjuvants

“…In addition to evoking a long-lasting immune stimulation, it allows slow adjuvant translocation to remote lymphoid organs and to the brain [123,[145][146][147]. Al adjuvants can cross the BBB and may induce immunoinflammatory responses in neural tissues: this translocation has been observed in animals exposed to ABAs, Al-containing vaccines, or ABA-trackers through intramuscular, subcutaneous, or intraperitoneal injections [143,[145][146][147][156][157][158][159]. These findings prompted Khan et al to conclude that repetitive doses of Al oxyhydroxide are "insidiously unsafe", particularly when given to newborns with an immature BBB.…”

Comparison of Immunogenicity Between a Candidate Live Attenuated Vaccine and an Inactivated Vaccine for Cache Valley Virus

“…In addition, the use of adjuvants is sometimes problematic. Aluminum hydroxide adjuvants have been shown to cause granulomas and potentially act as a contributor to severe wasting syndrome (de Miguel et al, 2021 ; Echeverría et al, 2020 ).…”