A review of virus infections of cataceans and the potential impact of morbilliviruses, poxviruses and papillomaviruses on host population dynamics.
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Viruses belonging to 9 families have been detected in cetaceans. We critically review the clinical features, pathology and epidemiology of the diseases they cause. Cetacean morbillivirus (family Paramyxoviridae) induces a serious disease with a high mortality rate and persists in several populations. It may have long-term effects on the dynamics of cetacean populations either as enzootic infection or recurrent epizootics. The latter presumably have the more profound impact due to removal of sexually mature individuals. Members of the family Poxviridae infect several species of odontocetes, resulting in ring and tattoo skin lesions. Although poxviruses apparently do not induce a high mortality, circumstancial evidence suggests they may be lethal in young animals lacking protective immunity, and thus may negatively affect net recruitment. Papillomaviruses (family Papovaviridae) cause genital warts in at least 3 species of cetaceans. In 10% of male Burmeister's porpoises Phocoena spinipinnis from Peru, lesions were sufficiently severe to at least hamper, if not impede, copulation. Members of the families Herpesviridae, Orthomyxoviridae and Rhabdoviridae were demonstrated in cetaceans suffering serious illnesses, but with the exception of a 'porpoise herpesvirus' their causative role is still tentative. Herpes-like viruses and caliciviruses (Caliciviridae) give rise to cutaneous diseases in Monodontidae and Delphinidae. Antibodies to several serotypes of caliciviruses were found in odontocetes and mysticetes. An unrecognized Hepadnaviridae was detected by serology in a captive Pacific white-sided dolphin Lagenorhynchus obliquidens with chronic persistent hepatitis. Adenoviruses (Adenoviridae) were isolated from the intestinal tracts of mysticeti and a beluga Delphinapterus leucas but were not associated with any pathologies. We discuss the potential impact of Paramyxoviridae, Poxviridae and Papovaviridae on the dynamics of several odontocete populations. (+info)
Molecular genetic evidence of a novel morbillivirus in a long-finned pilot whale (Globicephalus melas).
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A long-finned pilot whale with morbilliviral disease was stranded in New Jersey. An immunohistochemical stain demonstrated morbilliviral antigen. Reverse transcriptase-polymerase chain reaction for morbillivirus P and N genes was positive. Novel sequences most closely related to, but distinct from, those of dolphin and porpoise morbilliviruses suggest that this virus may represent a third member of the cetacean morbillivirus group. (+info)
Monoclonal antibody-based competitive enzyme-linked immunosorbent assay for detection of morbillivirus antibody in marine mammal sera.
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A competitive enzyme-linked immunosorbent assay (cELISA), using two monoclonal antibodies (MAbs), was developed and compared with the standard virus neutralization test (VNT) for detecting antibodies against canine distemper virus (CDV) and phocine distemper virus (PDV) in sera from dogs and various species of marine mammals. The test depends on the blocking of MAb binding to solid-phase antigen in the presence of positive serum. Test conditions were optimized by using control VNT-negative and -positive sera specific for CDV and PDV. A positive cutoff value of 30% inhibition, which represents the mean cutoff of a VNT-negative population (n = 623) plus 2 standard deviations, was adopted for the test. A total of 736 serum samples were tested by the new cELISA and by the VNT as the "gold standard." An unexpected but useful finding was the ability of this CDV- and PDV-specific cELISA to also detect antibodies against the related pair dolphin morbillivirus and porpoise morbillivirus. Based on a subpopulation of 625 sera used in statistical analyses, the overall sensitivity and specificity of cELISA relative to those of the VNT were 94.9 and 97.7%, respectively. Because the cELISA proved to be nearly as sensitive and specific as the VNT while being simpler and more rapid, it would be an adequate screening test for suspect CDV or PDV cases and would also be useful for epidemiological surveillance of morbilliviral infections in marine mammal populations. (+info)
Pathogenesis of two strains of lion (Panthera leo) morbillivirus in ferrets (Mustela putorius furo).
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Canine distemper virus (CDV) was previously considered to have a host range restricted to the canid family. In 1994, the virus was associated with sporadic outbreaks of distemper in captive felids. However, after severe mortality occurred in the Serengeti lions (Panthera leo), attention became focused on the pathogenesis of the virus and a concerted effort was made to identify the virus as CDV or a closely related feline morbillivirus. The present study was designed to explore the susceptibility of ferrets to challenge with two morbilliviruses isolated from lions and the protective effects of a modified-live mink distemper vaccine. Because mortality in ferrets infected with pathogenic CDV approaches 100%, the ferret was selected as a test animal. Two strains of lion morbillivirus were used as a challenge, A92-27/20 (California lion isolate) and A94-11/13 (Serengeti lion isolate). The two strains of lion morbillivirus were antigenically related to CDV (Rockborn strain), and ferrets were susceptible to both of the viruses when inoculated intraperitoneally. The inoculated ferrets were anorectic at 5-6 days postinoculation (PI), exhibited oculonasal discharge at 9-12 days PI, and became moribund at 12-22 days PI. Severe bilateral conjunctivitis was the typical clinical sign. Inclusion bodies characteristic of morbillivirus (eosinophilic, intranuclear, and intracytoplasmic) were distributed in many epithelial cells, including those of the skin, conjunctiva, gallbladder, liver, pancreas, stomach, trachea, lung, urinary bladder, and kidney. Virus was reisolated from selected lung tissues collected at necropsy and identified by CDV-specific immunofluorescence. Ferrets vaccinated with the mink distemper vaccine (Onderstepoort strain) were protected from challenge with the two lion strains, adding further support to the premise that the viruses are closely related to CDV. (+info)
Induction of adult-like antibody, Th1, and CTL responses to measles hemagglutinin by early life murine immunization with an attenuated vaccinia-derived NYVAC(K1L) viral vector.
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Although initially developed in adult animals, novel viral vectors expressing recombinant measles antigens must eventually prove their success in the early life setting, where the efficacy of the currently used live-attenuated measles virus vaccine is limited. The immunological requirements for vaccine candidates include the generation of protective antibody responses as well as the induction of Th1 and cytotoxic T lymphocytes (CTL) responses, which is challenging in the neonatal setting. Here, we report that young BALB/c mice immunized with a single dose of a vaccinia-based NYVAC(K1L) vector generate adult-like antihemagglutinin (HA) antibody responses as well as adult-like Th1 and CTL responses. Despite this strong immunogenicity in early life, antibody responses (but not T-cell responses) to a single dose of NYVAC(K1L)-HA remained susceptible to inhibition by preexisting measles antibodies, calling for use of prime-boost strategies. NYVAC(K1L)-HA is the first attenuated live viral vector demonstrated as capable of inducing adult-like antibody, Th1, and CTL responses against measles in an early life murine immunization model, a capacity previously only reported for measles DNA vaccines. (+info)
Immune responses to measles and mumps vaccination of infants at 6, 9, and 12 months.
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Immunizing infants against measles at the youngest age possible has the potential to reduce morbidity and mortality. The ability of infants at 6, 9, or 12 months to respond to measles and mumps vaccines was evaluated by measuring T cell proliferation, interferon-gamma production, and neutralizing antibody titers before and after vaccination. Infants in all age groups had equivalent cellular immune responses to measles or mumps viruses, with or without passive antibodies when immunized. In contrast, 6-month-old infants without passive antibodies had low geometric mean titers of antibody to measles or mumps viruses and low seroconversion rates. Geometric mean titers of antibody to measles virus increased if infants were revaccinated at 12 months. Six-month-old infants had limited humoral responses to paramyxovirus vaccines, whereas cellular immunity was equivalent to that of older infants. T cell responses can be established by immunization with these live attenuated virus vaccines during the first year, despite the presence of passive antibodies. (+info)
Morbilliviral dermatitis in seals.
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A juvenile female hooded seal (Cystophora cristata) and a juvenile male harp seal (Phoca groenlandica) stranded separately on the New Jersey (USA) coast and were taken to a marine mammal rehabilitation center. Both were lethargic and emaciated, had dermatitis, and died. Histologic skin lesions in the seals were similar and consisted of epidermal and follicular epithelial hyperplasia, hyperkeratosis, degeneration, and necrosis. The most distinctive finding was extensive syncytial zones bounded superficially by hyperkeratosis and deeply by hyperplastic basal cells. Eosinophilic intracytoplasmic inclusion bodies were present in epithelial cells. Morbilliviral antigen was demonstrated in the skin lesions by immunohistochemistry. Phocine distemper virus was detected in the skin by reverse transcription polymerase chain reaction and a phocine distemper virus-specific probe using the Southern blot technique. This is the first report of morbilliviral dermatitis in marine mammals. (+info)
Long-term sterilizing immunity to rinderpest in cattle vaccinated with a recombinant vaccinia virus expressing high levels of the fusion and hemagglutinin glycoproteins.
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Rinderpest is an acute and highly contagious viral disease of ruminants, often resulting in greater than 90% mortality. We have constructed a recombinant vaccinia virus vaccine (v2RVFH) that expresses both the fusion (F) and hemagglutinin (H) genes of rinderpest virus (RPV) under strong synthetic vaccinia virus promoters. v2RVFH-infected cells express high levels of the F and H glycoproteins and show extensive syncytium formation. Cattle vaccinated intramuscularly with as little as 10(3) PFU of v2RVFH and challenged 1 month later with a lethal dose of RPV were completely protected from clinical disease; the 50% protective dose was determined to be 10(2) PFU. Animals vaccinated with v2RVFH did not develop pock lesions and did not transmit the recombinant vaccinia virus to contact animals. Intramuscular vaccination of cattle with 10(8) PFU of v2RVFH provided long-term sterilizing immunity against rinderpest. In addition to being highly safe and efficacious, v2RVFH is a heat-stable, inexpensive, and easily administered vaccine that allows the serological differentiation between vaccinated and naturally infected animals. Consequently, mass vaccination of cattle with v2RVFH could eradicate rinderpest. (+info)