Duck enteritis virus 104388 Duck Plague Only ducks, geese, and swans are susceptible to duck plague. Other aquatic birds do not become infected, and the absence of mortality of American coot, shorebirds, and other waterbirds that may be present during a waterfowl die-off can be an important indication that duck plague may be involved. Susceptibility varies greatly among waterfowl species (Field Manual of Wildlife Diseases). Duck plague is caused by a herpesvirus. Infection often results in an acute, contagious, and fatal disease. As with many other herpesviruses, duck plague virus can establish inapparent infections in birds that survive exposure to it, a state referred to as latency. During latency, the virus cannot be detected by standard methods for virus isolation. Studies of domestic species of waterfowl have detected multiple strains of the virus that vary in their ability to cause disease and death. Little is known about the response of wild waterfowl to strain differences. Duck plague outbreaks are thought to be caused when birds that carry the virus shed it through fecal or oral discharge, thus releasing the virus into food and water with which susceptible birds may have contact. Experimental studies have demonstrated spontaneous virus shedding by duck plague carriers during spring. Changes in the duration of daylight and onset of breeding are thought to be physiological stresses that stimulate virus shedding at this time of year. The carriers are immune to the disease, but the virus shed by them causes infection and disease among susceptible waterfowl. Bird-to-bird contact and contact with virus that has contaminated the environment perpetuate an outbreak. Scavenging and decomposition of carcasses of infected birds also contaminate the environment by releasing viruses from tissues and body fluids. Virus transmission through the egg has been reported, but the role of the egg in the disease cycle remains to be resolved (Field Manual of Wildlife Diseases). Baboon Papio cynocephalus 9556 Bank vole Clethrionomys glareolus 447135 Bear Ursus americanus 9643 Birds Passeroidea 175121 Brown Trout Salmo trutta 8032 Buffalo Bison bison 9901 Carnivores Vulpes 9625 Cat Felis catus 9685 Catfishes Siluriformes 7995 Cattle Bos taurus 9913 Chicken Gallus gallus 9031 Chimpanzee Pan troglodytes 9598 chinchillas Chinchillidae 10150 Copper Pheasant Syrmaticus soemmerringii 9067 Deer Cervus elaphus 9860 Deer mouse Peromyscus maniculatus 10042 Dog Canis familiaris 9615 Ducks Anas 8835 Ferret Mustela putorius furo 9669 Fish Hyperotreti 117565 Gerbil Gerbillina 10045 Goat Capra hircus 9925 Gray wolf Canis lupus 9612 Guinea pig Cavia porcellus 10141 Hamster Mesocricetus auratus 10036 Horse Equus caballus 9796 Human Homo sapiens 9606 Macaque Macaca fascicularis 9541 Mongolian Gerbil Meriones unguiculatus 10047 Monkey Platyrrhini 9479 Mouse Mus musculus 10090 None None Parrot Psittacidae 9224 Pig Sus scrofa 9823 Rabbit Oryctolagus cuniculus 9986 Rainbow trout Oncorhynchus mykiss 8022 Rat Rattus 10114 Raven Corvus corax 56781 sei whale Balaenoptera borealis 9768 Sheep Ovis aries 9940 Squirrel Spermophilus richardsonii 37591 Tree shrew Tupaiidae 9393 Trouts, salmons & chars Salmoninae 504568 Turkey Meleagris gallopavo 9103 Vole Microtus ochrogaster 79684 Water buffalo Bubalus bubalis 391902 Duck Enteritis Virus Vaccine rDEV-UL26/27-P13C Recombinant vector vaccine Research duck enteritis virus [Ref5568:Yang et al., 2021] Intramuscular injection (i.m.) A bivalent duck enteritis virus recombinant vector vaccine that is made of a P1-P2a-33 cassette inserted between UL26 and UL27 of the viral genome (Yang et al., 2021). (Yang et al., 2021)The P1-P2A-3C cassette was inserted into the gene junction between UL26 and UL27. in the DEV vaccine strain genome. For transfection, we used the modified fosmids, C144-UL26/27-P13C, which replaced the parental fosmid C144. After being blindly passaged once in CEFs, DEV-typical plaques appeared in the CEFs transfected with the DNA combinations (Figure 2A). Electron microscopy confirmed the successful rescue of the recombinant viruses. Insertion of the P1-P2A-3C cassette at the proper site was confirmed by PCR and sequencing, using a forward primer specific to the P1 gene and a reverse primer matching the UL26 sequences. The recombinant DEV was designated rDEV-UL26/27-P13C, with the P1 and 3C genes inserted between UL26 and UL27 in the DEV genome. Intramuscular injection (i.m.) (Yang et al., 2021) whole virus Duck Enteritis Virus Vaccine rDEV-US7/8-P13C Recombinant vector vaccine Research duck enteritis virus [Ref5568:Yang et al., 2021] Intramuscular injection (i.m.) A bivalent duck enteritis virus recombinant vector vaccine that is made of a P1-P2a-33 cassette inserted between US7 and US8 of the viral genome (Yang et al., 2021). (Yang et al., 2021) The P1-P2A-3C cassette was inserted into the gene junction between US7 and US8 in the DEV vaccine strain genome. For transfection, we used the modified fosmid C343-US7/8-P13C, which replaced the parental fosmid C343. After being blindly passaged once in CEFs, DEV-typical plaques appeared in the CEFs transfected with the DNA combinations. Electron microscopy confirmed the successful rescue of the recombinant viruses. Insertion of the P1-P2A-3C cassette at the proper site was confirmed by PCR and sequencing, using a forward primer specific to the P1 gene and a reverse primer matching the US8 sequence. The recombinant DEV was designated rDEV-US7/8-P13C, with the P1 and 3C genes inserted between US7 and US8, in the DEV genome. Intramuscular injection (i.m.) (Yang et al., 2021) whole virus (Yang et al., 2021) Groups of 20 ducks were inoculated with 1000 ELD50 of the recombinant viruses to evaluate the antibody responses against DHAV-3 and DEV induced by the recombinant DEVs (Yang et al., 2021)All the animal experiments were performed using SPF ducks housed in filtered-air, negative-pressure isolation units. The ducks were given free access to food and water. To evaluate the protective efficacy of the recombinant viruses against challenge by the virulent DHAV-3 and DEV, each group of 20 ducks was inoculated subcutaneously with 1,000 times the 50% egg lethal dose (1000 ELD50) of the rescued viruses at 1 day of age. At 7 days post-vaccination, 10 ducks in each group were intramuscularly challenged with 100 ELD50 of the virulent DHAV-3 A3 strain, and the remaining 10 ducks were intramuscularly challenged with 1,000 minimum lethal doses of the virulent DEV CSC strain. Ten unvaccinated and unchallenged ducks were used as the healthy controls. The ducks were examined for clinical signs and mortality for 2 weeks after the challenge. The dead and surviving ducks were observed for gross lesions in the liver, spleen, kidneys, esophagus, intestine, thymus, and bursa (Yang et al., 2021) After the challenge, all the ducks in the challenge control group showed signs of disease, including listlessness, ruffled feathers, and anorexia, and died at 4 days post-challenge. Vaccination with rDEV-US7/8-P13C conferred 70% (7/10) protection against DEV challenge. These results suggest that the recombinant viruses also induced solid protection against lethal DEV challenge in ducks. Duck Virus Enteritis Modified Live Virus Vaccine (USDA: 1461.10) International Duck Research Cooperative, Inc. VO_0001737 Live, attenuated vaccine Licensed USA Field Manual of Wildlife Diseases website http://www.nwhc.usgs.gov/publications/field_manual/chapter_16.pdf