Risk factors associated with development of poxvirus lesions in hospitalized California sea lions

A new enzyme-linked immunosorbent assay for serological diagnosis of seal parapoxvirus infection in marine mammals

Introduction

Seal parapoxvirus (SPPV) infection has been reported among pinnipeds in aquaria in Japan; however, its seroprevalence is unknown. Therefore, an enzyme-linked immunosorbent assay (ELISA) was developed for serological diagnosis of SPPV infection.

Material and Methods

The gene encoding the major envelope protein of SPPV was cloned into the eukaryotic expression vector pAcGFP1-N1, which encodes the green fluorescence protein (GFP), thereby producing a fusion protein (Env-GFP). Parental and cloned vector DNA was independently transfected into cultured seal cells for the expression of GFP and Env-GFP. The wells of an ELISA plate were coated with either GFP- or Env-GFP-transfected cell lysates. The light absorbance of each serum sample was adjusted by subtracting the absorbance of GFP-coated wells from that of Env-GFP-coated wells. Sera from two spotted seals (Phoca largha), six beluga whales (Delphinapterus leucas), three Pacific white-sided dolphins (Lagenorhynchus obliquidens), and ten bottlenose dolphins (Tursiops truncatus) from an aquarium in Japan were examined using the ELISA.

Results

Positive reactions were not observed, except in one preserved sample collected ten years ago from a naturally SPPV-infected spotted seal.

Conclusion

The established ELISA could be useful in screening marine mammal sera for anti-SPPV antibodies.

Prevalence of and environmental factors associated with aerosolised Aspergillus spores at a zoological park

Aspergillus is a significant pathogen in zoological species, although information on environmental variables influencing fungal prevalence in zoological settings are lacking. The objective of the study was to estimate the prevalence of and to identify environmental factors associated with aerosolised Aspergillus spores at a zoological park to advance the understanding of fungal exposure as a first step towards improved mitigation strategies for susceptible animals. Twenty-one locations were sampled for presence of Aspergillus species using the SAS Super 180 Microbial Air Sampler, while twenty-two environmental factors were evaluated every two weeks at SeaWorld of California during two 12-month periods. In each period, the frequency of investigated environmental factors was compared between samples classified as positive or negative for Aspergillus species using logistic regression. Prevalence of Aspergillus was higher (P<0.05) during the second 12-month period (110/525 or 21 per cent), compared with the first period (62/483 or 13 per cent). In both periods, positive Aspergillus samples were associated with indoor sites without high-efficiency particulate air (HEPA) filtration systems and other infection control measures (adjusted OR=4.33 and 5.19, P<0.01) or outdoor sites (adjusted OR=2.50 and3.79, P≤0.05), compared to indoor sites with HEPA filtration systems and other infection control measures, after controlling for season. Burden of airborne Aspergillus can be higher in indoor sites without HEPA filtration systems than in outdoor sites. The use of HEPA filtration systems and other infection control measures can mitigate the burden of Aspergillus. Risk-based surveillance systems that target indoor areas without HEPA filtration systems can be an efficient approach for early detection of high burden of Aspergillus at zoological parks.

Complete genome sequence of a novel sea otterpox virus

Members of the Poxviridae family are large, double-stranded DNA viruses that replicate in the cytoplasm of their host cells. The subfamily Chordopoxvirinae contains viruses that infect a wide range of vertebrates including marine mammals within the Balaenidae, Delphinidae, Mustelidae, Odobenidae, Otariidae, Phocidae, and Phocoenidae families. Recently, a novel poxvirus was found in a northern sea otter pup (Enhydra lutris kenyoni) that stranded in Alaska in 2009. The phylogenetic relationships of marine mammal poxviruses are not well established because of the lack of complete genome sequences. The current study sequenced the entire sea otterpox virus Enhydra lutris kenyoni (SOPV-ELK) genome using an Illumina MiSeq sequencer. The SOPV-ELK genome is the smallest poxvirus genome known at 127,879 bp, is 68.7% A+T content, is predicted to encode 132 proteins, and has 2546 bp inverted terminal repeats at each end. Genetic and phylogenetic analyses based on the concatenated amino acid sequences of 7 chorodopoxvirus core genes revealed the SOPV-ELK is 52.5-74.1% divergent from other known chordopoxviruses and is most similar to pteropoxvirus from Australia (PTPV-Aus). SOPV-ELK represents a new chordopoxvirus species and may belong to a novel genus. SOPV-ELK encodes eight unique genes. While the function of six predicted genes remains unknown, two genes appear to function as novel immune-modulators. SOPV-ELK-003 appears to encode a novel interleukin-18 binding protein (IL-18 BP), based on limited sequence and structural similarity to other poxviral IL-18 BPs. SOPV-ELK-035 appears to encode a novel tumor necrosis factor receptor-like (TNFR) protein that may be associated with the depression of the host's antiviral response. Additionally, SOPV-ELK-036 encodes a tumor necrosis factor-like apoptosis-inducing ligand (TRAIL) protein that has previously only been found in PTPV-Aus. The SOPV-ELK genome is the first mustelid poxvirus and only the second poxvirus from a marine mammal to be fully sequenced. Sequencing of the SOPV-ELK genome is an important step in unraveling the position of marine mammal poxviruses within the larger Poxviridae phylogenetic tree and provides the necessary sequence to develop molecular tools for future diagnostics and epidemiological studies.

Sealpox virus in marine mammal rehabilitation facilities, North America, 2007-2009

Risks for human infection may be appreciable and can be reduced by workplace education.

Sealpox, a zoonotic disease affecting pinnipeds (seals and sea lions), can occur among captive and convalescing animals. We surveyed 1 worker each from 11 marine mammal centers and interviewed 31 other marine mammal workers to ascertain their knowledge of and experience with sealpox virus and to identify factors associated with sealpox virus outbreaks among pinnipeds in marine rehabilitation facilities. Demographic and health data were obtained for 1,423 pinnipeds at the 11 facilities. Among the 23 animals in which sealpox was clinically diagnosed, 4 arrived at the facility ill, 11 became ill <5 weeks after arrival, and 2 became ill >5 weeks after arrival; the timing of illness onset was unknown for 6 animals. Most infections occurred in pinnipeds <1 year of age. Nine affected animals were malnourished; 4 had additional illnesses. Sealpox had also occurred among workers at 2 facilities. Sealpox is a noteworthy zoonosis of rehabilitating convalescing pinnipeds; workplace education can help to minimize risks for human infection.