The judicious use of medications is a part of any balanced management program. Even so, disease o... more The judicious use of medications is a part of any balanced management program. Even so, disease outbreaks should be considered failures of nutrition, management, biosecurity, cleaning and disinfection, or vaccination programs. Preventative measures most effectively limit the adverse effects of disease but when they fail, medication can, and should be used to end the clinical signs of disease and return the flock to its normal balance. Medications should never be applied to flocks without also addressing the management failures that led to the outbreak (see Diseases of the Chicken, Chapter 27).
Three birds from a flock of 125 Cochin bantam chickens were true hermaphrodites, having both ovar... more Three birds from a flock of 125 Cochin bantam chickens were true hermaphrodites, having both ovarian and testicular tissues. These birds were recognizable by their intermediate comb size, intermediate plumage, and spur development. At necropsy, the left gonad of all three birds was an ovotestis and the right gonad was a testis. Microscopically, both ovarian follicles and seminiferous tubules were present within the ovotestes. Chromosomal analysis of lymphocytes from the whole blood of the third bird revealed triploid ZZW sex chromosomes. This high incidence (2.4%) of hermaphrodism suggests that there may be a hereditary predisposition for genetic intersex.
Hemorrhagic enteritis (HE) is an economically important disease of turkeys caused by a type II av... more Hemorrhagic enteritis (HE) is an economically important disease of turkeys caused by a type II aviadenovirus, hemorrhagic enteritis virus (HEV). The vaccines currently available to the commercial poultry producer are highly effective in preventing disease outbreaks; however, they are immunosuppressive. A recombinant fowl poxvirus (rFPV) expressing the native hexon of HEV has been shown to induce an anti-HEV humoral immune response in turkeys. In this study, the rFPV expressing the native hexon of HEV was compared with a commercial HEV vaccine (vxHEV) for its ability to protect turkeys from virulent HEV challenge. Complete protection from the enteritis of HE was achieved in experimental groups vaccinated with either the rFPV or the vxHEV. Lymphocyte stimulation was measured in turkeys inoculated with rFPV, vxHEV, or a sublethal dose of HEV or not inoculated. No statistically significant immunodepression was observed in turkeys receiving the rFPV.
Induced molting in egg-laying hens is an important method for maximizing hen egg production and q... more Induced molting in egg-laying hens is an important method for maximizing hen egg production and quality as well as hen health in commercial settings; however, there is growing societal concern over its effects on hen well-being. Using individual hens as their own controls, this research examined the behavior of hens subjected to different treatments of induced molting under premolt, molt, and postmolt conditions. Cage pecking increased in fast-induced subjects and aggression increased in fast-induced and nonfast-induced subjects during the molt. Gakel calling and several aspects of its acoustic structure were much higher during the molt condition in fast-induced subjects only. These data suggest that nonfast-induced molting treatments provide an effective method for inducing molting in hens and improving their well-being by minimizing discomfort due to food deprivation. In addition, these data further support that gakel vocalizations in hens may serve as an effective indicator for assessing well-being in a species otherwise behaviorally stoic in expressing stress or discomfort.
Subtype H6 influenza A viruses (IAVs) are commonly detected in wild birds and domestic poultry an... more Subtype H6 influenza A viruses (IAVs) are commonly detected in wild birds and domestic poultry and can infect humans. In 2010, a H6N6 virus emerged in southern China, and since then, it has caused sporadic infections among swine. We show that this virus binds to α2,6-linked and α2,3-linked sialic acids. Mutations at residues 222 (alanine to valine) and 228 (glycine to serine) of the virus hemagglutinin (HA) affected its receptor-binding properties. Experiments showed that the virus has limited transmissibility between ferrets through direct contact or through inhalation of infectious aerosolized droplets. The internal genes of the influenza A(H1N1)pdm09 virus, which is prevalent in swine worldwide, increases the replication efficiency of H6N6 IAV in the lower respiratory tract of ferrets but not its transmissibility between ferrets. These findings suggest H6N6 swine IAV (SIV) currently poses a moderate risk to public health, but its evolution and spread should be closely monitored.
Proceedings of the National Academy of Sciences of the United States of America, Jan 14, 2016
The influenza endonuclease is an essential subdomain of the viral RNA polymerase. It processes ho... more The influenza endonuclease is an essential subdomain of the viral RNA polymerase. It processes host pre-mRNAs to serve as primers for viral mRNA and is an attractive target for antiinfluenza drug discovery. Compound L-742,001 is a prototypical endonuclease inhibitor, and we found that repeated passaging of influenza virus in the presence of this drug did not lead to the development of resistant mutant strains. Reduced sensitivity to L-742,001 could only be induced by creating point mutations via a random mutagenesis strategy. These mutations mapped to the endonuclease active site where they can directly impact inhibitor binding. Engineered viruses containing the mutations showed resistance to L-742,001 both in vitro and in vivo, with only a modest reduction in fitness. Introduction of the mutations into a second virus also increased its resistance to the inhibitor. Using the isolated wild-type and mutant endonuclease domains, we used kinetics, inhibitor binding and crystallography t...
The specific-pathogen-free (SPF) flocks of chickens maintained by the Department of Microbiology ... more The specific-pathogen-free (SPF) flocks of chickens maintained by the Department of Microbiology and Immunology at Cornell University became infected, inadvertently, with chicken anaemia virus (CAV), as demonstrated by seroconversion. Chickens from five flocks representing three different strains were examined for the presence of CAV using nested PCR. Virus was detected in ovaries, infundibula, vas deferentia, testes and spleens. Ovaries were positive in 38 to 72% of the hens in four flocks with 13 to 56 birds examined per flock. Interestingly, the ovaries were often the only positive tissues, while a few hens had only positive spleens. In roosters, the vas deferens was positive in 30 to 79% of the birds with 5 to 19 birds examined per flock; the vas deferens was the only positive tissue in 20 to 37%. Individual cells in the theca externa and rare epithelial cells in the infundibular epithelium were positive for CAV by in situ PCR. Positive cells were not detected in testes or vas d...
An epidemiologic study was conducted to estimate the prevalence of Campylobacter spp. in accredit... more An epidemiologic study was conducted to estimate the prevalence of Campylobacter spp. in accredited Malaysian broiler chicken farms and to study the association between on-farm exposure variables and prevalence of Campylobacter isolation broiler chickens imported into Singapore. The study involved testing imported chickens from 1 Apr 2001 to 31 Jan 2003 for Campylobacter spp. Data on the exposure variables were retrieved from the farm database of the Agri-Food and Veterinary Authority of Singapore. Three putative exposure variables were examined in the study for association: biosecurity, production level and drinking water chlorination. Of the 150 farms tested during the study period, 105 (70%) were positive for Campylobacter. Based on statistical analysis of the 55 farms with complete data, only drinking water source was found to be statistically significant (P = 0.06) associated with Campylobacter spp. isolation in chickens imported into Singapore.
The judicious use of medications is a part of any balanced management program. Even so, disease o... more The judicious use of medications is a part of any balanced management program. Even so, disease outbreaks should be considered failures of nutrition, management, biosecurity, cleaning and disinfection, or vaccination programs. Preventative measures most effectively limit the adverse effects of disease but when they fail, medication can, and should be used to end the clinical signs of disease and return the flock to its normal balance. Medications should never be applied to flocks without also addressing the management failures that led to the outbreak (see Diseases of the Chicken, Chapter 27).
Three birds from a flock of 125 Cochin bantam chickens were true hermaphrodites, having both ovar... more Three birds from a flock of 125 Cochin bantam chickens were true hermaphrodites, having both ovarian and testicular tissues. These birds were recognizable by their intermediate comb size, intermediate plumage, and spur development. At necropsy, the left gonad of all three birds was an ovotestis and the right gonad was a testis. Microscopically, both ovarian follicles and seminiferous tubules were present within the ovotestes. Chromosomal analysis of lymphocytes from the whole blood of the third bird revealed triploid ZZW sex chromosomes. This high incidence (2.4%) of hermaphrodism suggests that there may be a hereditary predisposition for genetic intersex.
Hemorrhagic enteritis (HE) is an economically important disease of turkeys caused by a type II av... more Hemorrhagic enteritis (HE) is an economically important disease of turkeys caused by a type II aviadenovirus, hemorrhagic enteritis virus (HEV). The vaccines currently available to the commercial poultry producer are highly effective in preventing disease outbreaks; however, they are immunosuppressive. A recombinant fowl poxvirus (rFPV) expressing the native hexon of HEV has been shown to induce an anti-HEV humoral immune response in turkeys. In this study, the rFPV expressing the native hexon of HEV was compared with a commercial HEV vaccine (vxHEV) for its ability to protect turkeys from virulent HEV challenge. Complete protection from the enteritis of HE was achieved in experimental groups vaccinated with either the rFPV or the vxHEV. Lymphocyte stimulation was measured in turkeys inoculated with rFPV, vxHEV, or a sublethal dose of HEV or not inoculated. No statistically significant immunodepression was observed in turkeys receiving the rFPV.
Induced molting in egg-laying hens is an important method for maximizing hen egg production and q... more Induced molting in egg-laying hens is an important method for maximizing hen egg production and quality as well as hen health in commercial settings; however, there is growing societal concern over its effects on hen well-being. Using individual hens as their own controls, this research examined the behavior of hens subjected to different treatments of induced molting under premolt, molt, and postmolt conditions. Cage pecking increased in fast-induced subjects and aggression increased in fast-induced and nonfast-induced subjects during the molt. Gakel calling and several aspects of its acoustic structure were much higher during the molt condition in fast-induced subjects only. These data suggest that nonfast-induced molting treatments provide an effective method for inducing molting in hens and improving their well-being by minimizing discomfort due to food deprivation. In addition, these data further support that gakel vocalizations in hens may serve as an effective indicator for assessing well-being in a species otherwise behaviorally stoic in expressing stress or discomfort.
Subtype H6 influenza A viruses (IAVs) are commonly detected in wild birds and domestic poultry an... more Subtype H6 influenza A viruses (IAVs) are commonly detected in wild birds and domestic poultry and can infect humans. In 2010, a H6N6 virus emerged in southern China, and since then, it has caused sporadic infections among swine. We show that this virus binds to α2,6-linked and α2,3-linked sialic acids. Mutations at residues 222 (alanine to valine) and 228 (glycine to serine) of the virus hemagglutinin (HA) affected its receptor-binding properties. Experiments showed that the virus has limited transmissibility between ferrets through direct contact or through inhalation of infectious aerosolized droplets. The internal genes of the influenza A(H1N1)pdm09 virus, which is prevalent in swine worldwide, increases the replication efficiency of H6N6 IAV in the lower respiratory tract of ferrets but not its transmissibility between ferrets. These findings suggest H6N6 swine IAV (SIV) currently poses a moderate risk to public health, but its evolution and spread should be closely monitored.
Proceedings of the National Academy of Sciences of the United States of America, Jan 14, 2016
The influenza endonuclease is an essential subdomain of the viral RNA polymerase. It processes ho... more The influenza endonuclease is an essential subdomain of the viral RNA polymerase. It processes host pre-mRNAs to serve as primers for viral mRNA and is an attractive target for antiinfluenza drug discovery. Compound L-742,001 is a prototypical endonuclease inhibitor, and we found that repeated passaging of influenza virus in the presence of this drug did not lead to the development of resistant mutant strains. Reduced sensitivity to L-742,001 could only be induced by creating point mutations via a random mutagenesis strategy. These mutations mapped to the endonuclease active site where they can directly impact inhibitor binding. Engineered viruses containing the mutations showed resistance to L-742,001 both in vitro and in vivo, with only a modest reduction in fitness. Introduction of the mutations into a second virus also increased its resistance to the inhibitor. Using the isolated wild-type and mutant endonuclease domains, we used kinetics, inhibitor binding and crystallography t...
The specific-pathogen-free (SPF) flocks of chickens maintained by the Department of Microbiology ... more The specific-pathogen-free (SPF) flocks of chickens maintained by the Department of Microbiology and Immunology at Cornell University became infected, inadvertently, with chicken anaemia virus (CAV), as demonstrated by seroconversion. Chickens from five flocks representing three different strains were examined for the presence of CAV using nested PCR. Virus was detected in ovaries, infundibula, vas deferentia, testes and spleens. Ovaries were positive in 38 to 72% of the hens in four flocks with 13 to 56 birds examined per flock. Interestingly, the ovaries were often the only positive tissues, while a few hens had only positive spleens. In roosters, the vas deferens was positive in 30 to 79% of the birds with 5 to 19 birds examined per flock; the vas deferens was the only positive tissue in 20 to 37%. Individual cells in the theca externa and rare epithelial cells in the infundibular epithelium were positive for CAV by in situ PCR. Positive cells were not detected in testes or vas d...
An epidemiologic study was conducted to estimate the prevalence of Campylobacter spp. in accredit... more An epidemiologic study was conducted to estimate the prevalence of Campylobacter spp. in accredited Malaysian broiler chicken farms and to study the association between on-farm exposure variables and prevalence of Campylobacter isolation broiler chickens imported into Singapore. The study involved testing imported chickens from 1 Apr 2001 to 31 Jan 2003 for Campylobacter spp. Data on the exposure variables were retrieved from the farm database of the Agri-Food and Veterinary Authority of Singapore. Three putative exposure variables were examined in the study for association: biosecurity, production level and drinking water chlorination. Of the 150 farms tested during the study period, 105 (70%) were positive for Campylobacter. Based on statistical analysis of the 55 farms with complete data, only drinking water source was found to be statistically significant (P = 0.06) associated with Campylobacter spp. isolation in chickens imported into Singapore.
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