Lungworm seroprevalence in free-ranging harbour seals and molecular characterisation of marine mammal MSP

Abstract

Harbour seals (Phoca vitulina) are frequently infected with the lungworms Otostrongylus circumlitus and Parafilaroides gymnurus. The infection is often accompanied by secondary bacterial infections and can cause severe bronchopneumonia and even death in affected animals. Hitherto, the detection of lungworm infections was based on post mortem investigations from animals collected within stranding networks and a valid detection method for live free-ranging harbour seals was not available. Recently, an ELISA was developed for detecting lungworm antibodies in harbour seal serum, using major sperm protein (MSP) of the bovine lungworm, Dictyocaulus viviparus as recombinant diagnostic antigen. To determine lungworm seroprevalence in free-ranging harbour seals, serum was taken from four different seal age groups (n = 313) resulting in an overall prevalence of 17.9% (18.9% of males, 16.7% of females). 0.7% of harbour seals up to six weeks of age were seropositive, as were 89% of seals between six weeks and six months, 53.6% between six and 18 months and 24.2% of seals over 18 months of age. In the 18 months and over age group, seropositive animals showed statistically significant reductions in body weight (P = 0.003) and length (P < 0.001). Sera from lungworm infected harbour seals in rehabilitation (n = 6) revealed that duration of antibody persistence may be similar to that of lungworm infected cattle, but further studies are needed to confirm this. Phylogenetic analyses of MSP sequences of different marine and terrestrial mammal parasitic nematodes revealed that lungworm MSP of the genus Dictyocaulus (superfamily Trichostrongyloidea) is more closely related to metastrongylid marine mammal lungworms than to trichostrongylid nematodes of terrestrial hosts.

Prevalence and molecular characterisation of Acanthocephala in pinnipedia of the North and Baltic Seas

“…Parasitic infections with pulmonary nematodes, heartworms and seal lice in harbour seals seem to be age-dependent ( Claussen et al, 1991 , Lehnert et al, 2007 , Lehnert et al, 2016 , Ulrich et al, 2016 ), probably due to development of protective immunity and/or a shift in the prey spectrum during adolescence ( Lehnert et al, 2007 , Lehnert et al, 2016 , Lundström et al, 2010 ). The latter might also be assumed for acanthocephalan infections, as studies during the first PDV epidemic revealed that young seals were less frequently infected with Corynosoma spp.…”

Brucella pinnipedialis in lungworms Parafilaroides sp. and Pacific harbor seals Phoca vitulina richardsi: proposed pathogenesis

“…Results of a serologic survey of harbor seals in Alaska indicated seroconversion occurring between 4 and 8 mo of age (Hoover-Miller et al 2017). This corresponds to the time when seals become parasitized with lungworms as they begin to feed on prey after a post-weaning fast (Muelbert & Bowen 1993, Ulrich et al 2016. With age, both lungworm infection and B. pinnipedialis infection decreases.…”

Detection of specific antibodies in cats infected with the lung nematode Aelurostrongylus abstrusus

“…To ensure usability of D. viviparus recombinant MSP for detection of anti-A. abstrusus MSP antibodies, genomic DNA of A. abstrusus L1 was isolated and amplified with degenerate primers as described by Ulrich et al (2016). Degenerate primer stretches were removed from the sequenced A.…”