Ictions. At present, only a few studies have evaluated the prevalence of AI in backyard flocks. Government agencies are carefully monitoring and inspecting live bird markets, commercial flocks, and migratory bird populations. However, there remains little surveillance of private poultry flocks which are not confined to the same strict biosecurity practices as their commercial counterparts. Therefore, a cross-sectional study was conducted in non-commercial backyard poultry flocks using a convenience sampling method across three regions of Maryland from July 2011 to August 2011. The objective of this study was to investigate the prevalence and seroprevalence of avian influenza in this potentially vulnerable population and to evaluate biosecurity risk factors associated with positive findings.Serologuc AssayscELISA. Serum was separated from the clot by centrifugation at 1,3006 g for 23727046 10 minutes in a swinging bucket centrifuge and stored at 220uC. Evaluation for antibodies to influenza A viruses in sera was carried out using Synbiotics USDA-licensed screening kit, Flu DETECTH BE. The Flu DETECTH BE kit is designed to detect antibodies against a recombinant SPDP web nucleoprotein. Plates were read using the ELX800 microplate reader (BIO-TEK instruments, INC., Winooski, VT) and ProFILE3 software (Synbiotics Corp., Kansas City, MO). Positive serum was determined based on the serum sample to negative control ratio (SN,0.6) designated by the Synbiotics kit. SN,0.6 is equivalent to 40 inhibition.VirusesInfluenza virus strains A/Mallard/PA/10218/84 (H5N2), A/ Mallard/Alberta/24/01 (H7N3), and A/Quail/Arkansas/202091/93 (H9N2) were generously provided by Dr. Daniel Perez from the University of Maryland (College Park, MD). Viruses were propagated in nine day-old embryonated chicken eggs for 48 hours as previously described [13].Materials and Methods Ethics StatementThis study was approved in accordance with the University of Maryland’s Institutional Review Board (IRB #11-0335), Federal Policy for the DprE1-IN-2 web Protection of Human Subjects (45 CFR 46), and Institutional Animal Care and Use Committee (IACUC # R-1127). Written informed consent was obtained from all participants prior to survey and sample collection.Hemagglutination (HA) and Hemagglutination Inhibition (HI) AssaysHA titers were determined using 50 ul of 0.5 chicken red blood cells in PBS to 50 ul of a two-fold serial dilution of virus and PBS. Microtiter plates were incubated for 30 minutes at room temperature. HA titers were subsequently calculated as the reciprocal value of the highest dilution that caused complete hemagglutination. HI titrations were calculated by performing a serial two-fold dilution of 25 ul of Receptor Destroying Enzyme (RDE) treated sample and control serum with 25 ul of PBS. Twenty five ul of virus dilution containing 4 HA units/25 ul was then added to each well. Wells were incubated at room temperature for 30 minutes and 50 ul of 0.5 chicken red blood cell suspension was added. After 30 minutes HI titers were calculated as the reciprocal of the serum dilution that inhibited hemagglutination. A titer of 1:128 was used to define the reactivity of samples. This was the titer of the last well in a serial dilution of the positive control column that completely inhibited hemagglutination [14].Study Design and PopulationThis study used a cross-sectional survey design and convenience sampling method to determine biosecurity risk factors and disease prevalence among Maryland non-commerc.Ictions. At present, only a few studies have evaluated the prevalence of AI in backyard flocks. Government agencies are carefully monitoring and inspecting live bird markets, commercial flocks, and migratory bird populations. However, there remains little surveillance of private poultry flocks which are not confined to the same strict biosecurity practices as their commercial counterparts. Therefore, a cross-sectional study was conducted in non-commercial backyard poultry flocks using a convenience sampling method across three regions of Maryland from July 2011 to August 2011. The objective of this study was to investigate the prevalence and seroprevalence of avian influenza in this potentially vulnerable population and to evaluate biosecurity risk factors associated with positive findings.Serologuc AssayscELISA. Serum was separated from the clot by centrifugation at 1,3006 g for 23727046 10 minutes in a swinging bucket centrifuge and stored at 220uC. Evaluation for antibodies to influenza A viruses in sera was carried out using Synbiotics USDA-licensed screening kit, Flu DETECTH BE. The Flu DETECTH BE kit is designed to detect antibodies against a recombinant nucleoprotein. Plates were read using the ELX800 microplate reader (BIO-TEK instruments, INC., Winooski, VT) and ProFILE3 software (Synbiotics Corp., Kansas City, MO). Positive serum was determined based on the serum sample to negative control ratio (SN,0.6) designated by the Synbiotics kit. SN,0.6 is equivalent to 40 inhibition.VirusesInfluenza virus strains A/Mallard/PA/10218/84 (H5N2), A/ Mallard/Alberta/24/01 (H7N3), and A/Quail/Arkansas/202091/93 (H9N2) were generously provided by Dr. Daniel Perez from the University of Maryland (College Park, MD). Viruses were propagated in nine day-old embryonated chicken eggs for 48 hours as previously described [13].Materials and Methods Ethics StatementThis study was approved in accordance with the University of Maryland’s Institutional Review Board (IRB #11-0335), Federal Policy for the Protection of Human Subjects (45 CFR 46), and Institutional Animal Care and Use Committee (IACUC # R-1127). Written informed consent was obtained from all participants prior to survey and sample collection.Hemagglutination (HA) and Hemagglutination Inhibition (HI) AssaysHA titers were determined using 50 ul of 0.5 chicken red blood cells in PBS to 50 ul of a two-fold serial dilution of virus and PBS. Microtiter plates were incubated for 30 minutes at room temperature. HA titers were subsequently calculated as the reciprocal value of the highest dilution that caused complete hemagglutination. HI titrations were calculated by performing a serial two-fold dilution of 25 ul of Receptor Destroying Enzyme (RDE) treated sample and control serum with 25 ul of PBS. Twenty five ul of virus dilution containing 4 HA units/25 ul was then added to each well. Wells were incubated at room temperature for 30 minutes and 50 ul of 0.5 chicken red blood cell suspension was added. After 30 minutes HI titers were calculated as the reciprocal of the serum dilution that inhibited hemagglutination. A titer of 1:128 was used to define the reactivity of samples. This was the titer of the last well in a serial dilution of the positive control column that completely inhibited hemagglutination [14].Study Design and PopulationThis study used a cross-sectional survey design and convenience sampling method to determine biosecurity risk factors and disease prevalence among Maryland non-commerc.
