Yazid Abdad - Academia.edu (original) (raw)

Papers by Yazid Abdad

Research paper thumbnail of Seroprevalence and risk factors for Rickettsia felis exposure in dogs from Southeast Queensland and the Northern Territory, Australia

Parasites & vectors, 2013

Background: The recent detection of Rickettsia felis DNA in dogs in Australia suggests that dogs ... more Background: The recent detection of Rickettsia felis DNA in dogs in Australia suggests that dogs are potential mammalian reservoir hosts for this emerging rickettsia. To date, there is no published report addressing the seroprevalence of R. felis in dogs in Australia. Methods: Antigens for R. felis were produced by inoculating confluent XTC-2 monolayer cell cultures with three pools of cat flea (Ctenocephalides felis) homogenates. Infection was confirmed by real-time (qPCR), conventional or nested PCRs targeting the ompB, gltA, 17 kDa and ompA genes. Two hundred and ninety-two dogs from Southeast Queensland and the Northern Territory were tested for the presence of R. felis antibodies using a microimmunofluorescence (IF) test and the seroprevalence and associated risk factors for exposure were determined using both uni-and multi-variate analyses.

Research paper thumbnail of Differential activities of alpha/beta IFN subtypes against influenza virus in vivo and enhancement of specific immune responses in DNA vaccinated mice expressing haemagglutinin and nucleoprotein

Vaccine, 2007

Vaccines are urgently needed to elicit immunity to different influenza virus strains. DNA vaccine... more Vaccines are urgently needed to elicit immunity to different influenza virus strains. DNA vaccines can elicit partial protective immunity, however their efficacy requires improvement. We assessed the capacity of individual type I IFN multigene family members as subtype transgenes to abrogate influenza virus replication in a vaccination/challenge mouse model. Differences in antiviral efficacy were found among the subtypes with IFNA5 and IFNA6 being most effective, while IFNA1 was the least effective in reducing lung virus replication. Mice vaccinated with combinatorial HA/IFNA6 or NP/IFNA6 showed reduced lung viral titres, clinical score, body weight loss, and pulmonary tissue damage compared to IFNA6, HA, or NP viral vaccination alone. In addition, IFNA6 increased IgG2a titres with upregulation of IFN-gamma response in the respiratory tract. We conclude that IFN-alpha 6 has antiviral and immunomodulatory effects, which improve efficacy of DNA vaccines for enhanced control of influenza.

Research paper thumbnail of Molecular evidence supports the role of dogs as potential reservoirs for Rickettsia felis

Vector-Borne and …, Jan 1, 2011

Rickettsia felis causes flea-borne spotted fever in humans worldwide. The cat flea, Ctenocephalid... more Rickettsia felis causes flea-borne spotted fever in humans worldwide. The cat flea, Ctenocephalides felis, serves as vector and reservoir host for this disease agent. To determine the role of dogs as potential reservoir hosts for spotted fever group rickettsiae, we screened blood from 100 pound dogs in Southeast Queensland by using a highly sensitive genus-specific PCR. Nine of the pound dogs were positive for rickettsial DNA and subsequent molecular sequencing confirmed amplification of R. felis. A high prevalence of R. felis in dogs in our study suggests that dogs may act as an important reservoir host for R. felis and as a potential source of human rickettsial infection.

Research paper thumbnail of Differential activities of alpha/beta IFN subtypes against influenza virus in vivo and enhancement of specific immune responses in DNA vaccinated mice expressing …

Vaccine, Jan 1, 2007

Vaccines are urgently needed to elicit immunity to different influenza virus strains. DNA vaccine... more Vaccines are urgently needed to elicit immunity to different influenza virus strains. DNA vaccines can elicit partial protective immunity, however their efficacy requires improvement. We assessed the capacity of individual type I IFN multigene family members as subtype transgenes to abrogate influenza virus replication in a vaccination/challenge mouse model. Differences in antiviral efficacy were found among the subtypes with IFNA5 and IFNA6 being most effective, while IFNA1 was the least effective in reducing lung virus replication. Mice vaccinated with combinatorial HA/IFNA6 or NP/IFNA6 showed reduced lung viral titres, clinical score, body weight loss, and pulmonary tissue damage compared to IFNA6, HA, or NP viral vaccination alone. In addition, IFNA6 increased IgG2a titres with upregulation of IFNgamma response in the respiratory tract. We conclude that IFN-alpha 6 has antiviral and immunomodulatory effects, which improve efficacy of DNA vaccines for enhanced control of influenza.

Research paper thumbnail of An epidemiological and serological study of Rickettsia in Western Australia

Research paper thumbnail of High prevalence of< i> Rickettsia gravesii</i> sp. nov. in< i> Amblyomma triguttatum</i> collected from feral pigs

Veterinary microbiology, Jan 1, 2010

Research paper thumbnail of Rickettsia felis, an emerging flea-transmitted human pathogen

Emerging Health Threats Journal, Jan 1, 2011

Rickettsia felis was first recognised two decades ago and has now been described as endemic to al... more Rickettsia felis was first recognised two decades ago and has now been described as endemic to all continents except Antarctica. The rickettsiosis caused by R. felis is known as flea-borne spotted fever or cat-flea typhus. The large number of arthropod species found to harbour R. felis and that may act as potential vectors support the view that it is a pan-global microbe. The main arthropod reservoir and vector is the cat flea, Ctenocephalides felis, yet more than 20 other species of fleas, ticks, and mites species have been reported to harbour R. felis. Few bacterial pathogens of humans have been found associated with such a diverse range of invertebrates. With the projected increase in global temperature over the next century, there is concern that changes to the ecology and distribution of R. felis vectors may adversely impact public health.

Research paper thumbnail of Seroprevalence and risk factors for Rickettsia felis exposure in dogs from Southeast Queensland and the Northern Territory, Australia

Parasites & vectors, 2013

Background: The recent detection of Rickettsia felis DNA in dogs in Australia suggests that dogs ... more Background: The recent detection of Rickettsia felis DNA in dogs in Australia suggests that dogs are potential mammalian reservoir hosts for this emerging rickettsia. To date, there is no published report addressing the seroprevalence of R. felis in dogs in Australia. Methods: Antigens for R. felis were produced by inoculating confluent XTC-2 monolayer cell cultures with three pools of cat flea (Ctenocephalides felis) homogenates. Infection was confirmed by real-time (qPCR), conventional or nested PCRs targeting the ompB, gltA, 17 kDa and ompA genes. Two hundred and ninety-two dogs from Southeast Queensland and the Northern Territory were tested for the presence of R. felis antibodies using a microimmunofluorescence (IF) test and the seroprevalence and associated risk factors for exposure were determined using both uni-and multi-variate analyses.

Research paper thumbnail of Differential activities of alpha/beta IFN subtypes against influenza virus in vivo and enhancement of specific immune responses in DNA vaccinated mice expressing haemagglutinin and nucleoprotein

Vaccine, 2007

Vaccines are urgently needed to elicit immunity to different influenza virus strains. DNA vaccine... more Vaccines are urgently needed to elicit immunity to different influenza virus strains. DNA vaccines can elicit partial protective immunity, however their efficacy requires improvement. We assessed the capacity of individual type I IFN multigene family members as subtype transgenes to abrogate influenza virus replication in a vaccination/challenge mouse model. Differences in antiviral efficacy were found among the subtypes with IFNA5 and IFNA6 being most effective, while IFNA1 was the least effective in reducing lung virus replication. Mice vaccinated with combinatorial HA/IFNA6 or NP/IFNA6 showed reduced lung viral titres, clinical score, body weight loss, and pulmonary tissue damage compared to IFNA6, HA, or NP viral vaccination alone. In addition, IFNA6 increased IgG2a titres with upregulation of IFN-gamma response in the respiratory tract. We conclude that IFN-alpha 6 has antiviral and immunomodulatory effects, which improve efficacy of DNA vaccines for enhanced control of influenza.

Research paper thumbnail of Molecular evidence supports the role of dogs as potential reservoirs for Rickettsia felis

Vector-Borne and …, Jan 1, 2011

Rickettsia felis causes flea-borne spotted fever in humans worldwide. The cat flea, Ctenocephalid... more Rickettsia felis causes flea-borne spotted fever in humans worldwide. The cat flea, Ctenocephalides felis, serves as vector and reservoir host for this disease agent. To determine the role of dogs as potential reservoir hosts for spotted fever group rickettsiae, we screened blood from 100 pound dogs in Southeast Queensland by using a highly sensitive genus-specific PCR. Nine of the pound dogs were positive for rickettsial DNA and subsequent molecular sequencing confirmed amplification of R. felis. A high prevalence of R. felis in dogs in our study suggests that dogs may act as an important reservoir host for R. felis and as a potential source of human rickettsial infection.

Research paper thumbnail of Differential activities of alpha/beta IFN subtypes against influenza virus in vivo and enhancement of specific immune responses in DNA vaccinated mice expressing …

Vaccine, Jan 1, 2007

Vaccines are urgently needed to elicit immunity to different influenza virus strains. DNA vaccine... more Vaccines are urgently needed to elicit immunity to different influenza virus strains. DNA vaccines can elicit partial protective immunity, however their efficacy requires improvement. We assessed the capacity of individual type I IFN multigene family members as subtype transgenes to abrogate influenza virus replication in a vaccination/challenge mouse model. Differences in antiviral efficacy were found among the subtypes with IFNA5 and IFNA6 being most effective, while IFNA1 was the least effective in reducing lung virus replication. Mice vaccinated with combinatorial HA/IFNA6 or NP/IFNA6 showed reduced lung viral titres, clinical score, body weight loss, and pulmonary tissue damage compared to IFNA6, HA, or NP viral vaccination alone. In addition, IFNA6 increased IgG2a titres with upregulation of IFNgamma response in the respiratory tract. We conclude that IFN-alpha 6 has antiviral and immunomodulatory effects, which improve efficacy of DNA vaccines for enhanced control of influenza.

Research paper thumbnail of An epidemiological and serological study of Rickettsia in Western Australia

Research paper thumbnail of High prevalence of< i> Rickettsia gravesii</i> sp. nov. in< i> Amblyomma triguttatum</i> collected from feral pigs

Veterinary microbiology, Jan 1, 2010

Research paper thumbnail of Rickettsia felis, an emerging flea-transmitted human pathogen

Emerging Health Threats Journal, Jan 1, 2011

Rickettsia felis was first recognised two decades ago and has now been described as endemic to al... more Rickettsia felis was first recognised two decades ago and has now been described as endemic to all continents except Antarctica. The rickettsiosis caused by R. felis is known as flea-borne spotted fever or cat-flea typhus. The large number of arthropod species found to harbour R. felis and that may act as potential vectors support the view that it is a pan-global microbe. The main arthropod reservoir and vector is the cat flea, Ctenocephalides felis, yet more than 20 other species of fleas, ticks, and mites species have been reported to harbour R. felis. Few bacterial pathogens of humans have been found associated with such a diverse range of invertebrates. With the projected increase in global temperature over the next century, there is concern that changes to the ecology and distribution of R. felis vectors may adversely impact public health.