Brucella ceti sequence type 23, 26, and 27 infections in North American cetaceans

Abstract

Brucella ceti infection is associated with a variety of disease outcomes in cetaceans globally. Multiple genotypes of B. ceti have been identified. This retrospective aimed to determine if specific lesions were associated with different B. ceti DNA sequence types (STs). Characterization of ST was performed on 163 samples from 88 free-ranging cetaceans, including common bottlenose dolphin Tursiops truncatus (T.t.; n = 73), common short-beaked dolphin Delphinus delphis (D.d.; n = 7), striped dolphin Stenella coeruleoalba (n = 3), Pacific white-sided dolphin Lagenorhynchus obliquidens (n = 2), sperm whale Physeter macrocephalus (n = 2), and harbour porpoise Phocoena phocoena (n = 1), that stranded along the coast of the US mainland and Hawaii. ST was determined using a previously described insertion sequence 711 quantitative PCR. Concordance with 9-locus multi-locus sequence typing was assessed in a subset of samples (n = 18). ST 26 was most commonly identified in adult dolphins along the US east coast with non-suppurative meningoencephalitis (p = 0.009). Animals infected with ST 27 were predominately perinates that were aborted or died shortly after birth with evidence of in utero pneumonia (p = 0.035). Reproductive tract inflammation and meningoencephalitis were also observed in adult T.t. and D.d. with ST 27, though low sample size limited interpretation. ST 23 infections can cause disease in cetacean families other than porpoises (Phocoenidae), including neurobrucellosis in D.d. In total, 11 animals were potentially infected with multiple STs. These data indicate differences in pathogenesis among B. ceti STs in free-ranging cetaceans, and infection with multiple STs is possible.

Serological Detection of Marine Origin Brucella Exposure in Two Alaska Beluga Stocks

“…Brucella infection in cetaceans is diagnosed by histology, immunohistochemistry, bacterial culture, PCR, and serology [ 5 , 42 ]. Serology, albeit a useful diagnostic surveillance tool, is insufficient by itself to determine active infection.…”

“…The role of infectious diseases among beluga stocks is less well-understood, however, climate change is predicted to increase infectious disease outbreaks and extent among marine-mammal populations [for review see 4]. Among the various viral and bacterial pathogens known to affect cetaceans, marine Brucella , in particular B. ceti , is an emerging disease concern among free-ranging cetaceans worldwide and in North America [ 5 ].…”

“…infection in cetaceans shows a broad and variable disease presentation and may occur without clinical indication of disease, making it difficult to interpret the significance of exposure. Marine brucellosis has been associated with lesions in the brain, cardiovascular system, lungs, bones, skin, and reproductive organs [ 5 , 12 , 13 , 14 , 15 , 16 ]. Reproductive failure is of particular concern for species with inherently low reproductive potential and for threatened and endangered marine-mammal populations.…”

“…remains ill-defined, with only a few cases of marine Brucella infection with B. ceti sequence type 27 documented in humans [ 15 , 21 ]. ST27 has been identified in bottlenose dolphins, common dolphins, sperm whales ( Physeter microcephalus ), dwarf sperm whales and California sea lions ( Zalophus californianus ) [ 5 , 11 , 19 ]. In Alaska, B. pinnipedialis is the only strain that has been identified in belugas [ 11 ].…”

Brucella ceti and Brucella pinnipedialis genome characterization unveils genetic features that highlight their zoonotic potential

“…Within this picture, undertaking a comprehensive characterization of the B. ceti and B. pinnipedialis genome is a preliminary and fundamental step to either understand the genetic features that contributed to the evolutionary success of these organisms infecting their hosts and spread through the marine environment or to identify the genetic basis of brucellosis pathological phenotypes. Although research efforts have recently focused in this direction, so far molecular investigations have mainly concentrated on genomic surveillance (Duvnjak et al, 2017 ; Maquart et al, 2008 ; Ueno, Kumagai, et al, 2020 ; Zygmunt et al, 2021 ) and molecular epidemiology (Garofolo et al, 2020 ; Kroese et al, 2018 ; Lambourn et al, 2013 ; Tian et al, 2019 ; Ueno, Yanagisawa, et al, 2020 ), evolutionary phylogenesis (Audic et al, 2011 ; Duncan et al, 2014 ; Suárez‐Esquivel et al, 2017 ; Whatmore et al, 2017 ) and more recently on the differences in pathogenesis between genotypes (Curtiss et al, 2022 ; Damiano et al, 2015 ; Ocampo‐Sosa & García‐Lobo, 2008 ), whereas functional characterization of B. ceti and B. pinnipedialis genes has gained less attention. Our study provides a comprehensive description of core‐ and pan‐genome elements from all available (as of February 2022) B. ceti and B. pinnipedialis full genomes and raw sequencing data, with a specific focus on putative genetic determinants for virulence and pathogenesis.…”