Assessment of the Safety and Efficacy of an Oral Probiotic-Based Vaccine Against Aspergillus Infection in Captive-Bred Humboldt Penguins (Spheniscus humboldti)

Abstract

Aspergillosis is a fungal infection caused mainly by Aspergillus fumigatus that often results in respiratory disease in birds. Aspergillosis is a major cause of morbidity and mortality in captive-bred penguin species. Currently, there is no registered vaccine to prevent aspergillosis. Recent research demonstrated that oral administration of gram-negative bacteria expressing high levels of galactose-α-1,3-galactose (α-Gal) modulates anti-α-Gal immunity and protects turkeys from clinical aspergillosis caused by experimental A. fumigatus infection. The role of anti-α-Gal immunity in penguins has not been studied. Here, we tested the distribution of α-1,3-galactosyltransferase (α1,3GT) genes in the fecal microbiome of Humboldt penguins (Spheniscus humboldti). The occurrence of natural anti-α-Gal antibodies (Abs) in sera and eggs of healthy Humboldt penguins was also assessed. A trial was then conducted to test whether oral administration of Escherichia coli Nissle, expressing high α-Gal levels, modulates anti-α-Gal immunity in a colony of Humboldt penguins. Animals in the vaccination and placebo groups were evaluated before the trial and followed for one year for aspergillosis detection using a diagnostic panel including computed tomography scans, capillary zone electrophoresis, 3-hydroxybutyrate levels, and anti-A. fumigatus Abs. Anti-α-Gal Abs were detected in sera (IgM and IgY) and eggs (IgY) of healthy penguins. Microbiota analysis and functional predictions revealed the presence of α1,3GT genes in the microbiota of Humboldt penguins and other penguin species. A strong decrease in anti-α-Gal IgM levels was observed in all animals in the placebo group three months after vaccination protocol. This decrease was not observed in E. coli Nissle-treated penguins. After the vaccination protocol, we found a positive correlation between anti-E. coli IgY and anti-α-Gal IgY in the E. coli Nissle group, suggesting a correlation between the presence of the bacteria and these Abs. During the study period, three penguins exhibited respiratory signs consistent with aspergillosis. Two were from the placebo group whose symptoms resolved with specific treatments, while a single vaccinated individual developed fatal respiratory aspergillosis eight months after the trial. We conclude that E. coli Nissle represents a safe potential probiotic with a protective effect against aspergillosis in Humboldt penguins that deserves to be further explored for therapeutic uses in these animals.

Clonal dissemination of Acinetobacter radioresistens among Humboldt penguins (Spheniscus humboldti) inhabiting a barren northern Peruvian island

“…Nevertheless, while most studies focused on the direct or indirect detection of microorganisms in wild or captive Humboldt penguins have been addressed to pathogenic issues [ 44–46 ], in one study describing the gut microbiota of captive Humboldt penguins, the presence of Acinetobacter spp. ranked among the taxa with the highest relative abundance [ 47 ].…”

Nationwide Survey about the Occurrence of Aspergillosis in Captive Penguins in Zoos and Aquariums in Japan

“…Therefore, instead of other measures, the risk of acquiring Aspergillus spores from the rearing environment must be eliminated. New technologies, such as diagnosis with image analysis [ 25 , 27 ], plasma biomarkers [ 38 ], and probiotic-based vaccination [ 39 ], might be useful in reducing the incidence of aspergillosis among penguins. However, environmental interventions might be an effective and easy method for decreasing the risk of aspergillosis, which should be considered a priority.…”

Composition, Diversity and Sex-Related Differences in Intestinal Microbiota in Captive African Penguins (Spheniscus demersus)

“…Currently, to our knowledge, there has been only one study investigating the intestinal microbiota of Spheniscus species ( Spheniscus humboldti ). However, this study did not show the composition of the intestinal microbiota at the phylum level, and its sample size was low ( n = 4) [ 22 ]. A previous study showed that the predominant bacteria in captive Chinstrap penguins are Proteobacteria, Firmicutes, Fusobacteria and Bacteroidetes [ 23 ].…”