7 research outputs found
Seroanalysis of Felis catus gammaherpesvirus 1 infection in domestic cats
Includes bibliographical references.2015 Summer.We recently described a novel herpesvirus of domestic cats, Felis catus gammaherpesvirus 1 (FcaGHV1). FcaGHV1 is a member of the gammaherpesvirus subfamily, which also includes the human cancer-associated herpesviruses, Epstein-Barr virus (EBV) and Kaposi’s sarcoma-associated herpesvirus (KSHV). To determine FcaGHV1 antigens that elicit a detectable humoral-immune response in naturally-infected domestic cats, I chose to evaluate seven FcaGHV1 proteins. These proteins are conserved across the subfamily and antigenic in other gammaherpesvirus infections. I amplified and cloned each of the seven FcaGHV1 genes into a mammalian expression vector and transfected intact clones into Crandell Rees feline kidney (CRFK) cells. I developed an immunofluorescent antibody test using transfected cells exposed to sera from nine shelter cats diagnosed as FcaGHV1-positive by quantitative PCR (qPCR) of blood-cell DNA. This analysis indicated that tegument proteins ORF52 and ORF38 reacted most consistently with serum from cats with positive FcaGHV1-qPCR reactions. Based on these results, recombinant antigens were used to develop two optimized indirect ELISAs. Genes for ORF52 and ORF38 were cloned into a mammalian expression vector. Antigens were produced in a transient transfection system and purified using immunoprecipitation. Indirect ELISA conditions were optimized using known positive and negative controls. Using the two optimized ELISAs, I screened sera from 133 shelter cats that had been previously tested by FcaGHV1-qPCR. Seroprevalence of FcaGHV1 reactive antibodies was 32%, compared to the previously published 16% prevalence evaluated by qPCR. Nineteen of twenty qPCR positive cats were also seroreactive against one or both antigens on ELISA. Sera from 24 cats were seropositive based upon ELISA testing, but negative using qPCR analysis. Risk factors identified in previous publications were confirmed by ELISA, namely geographic location, male sex, adult age, and association of FcaGHV1 with several co-infections. Based on our knowledge of gammaherpesvirus latency, this ELISA provides evidence of viral exposure, while qPCR viral DNA detection likely represents reactivation from latency or primary infection. The addition of serologic analysis as a measurement of FcaGHV1 exposure will aid in determining association of FcaGHV1 with disease and routes of transmission
Closing the gap on causal processes of infection risk from cross-sectional data:structural equation models to understand infection and co-infection
BACKGROUND: Epidemiological studies of disease exposure risk are frequently based on observational, cross-sectional data, and use statistical approaches as crucial tools for formalising causal processes and making predictions of exposure risks. However, an acknowledged limitation of traditional models is that the inferred relationships are correlational, cannot easily distinguish direct from indirect determinants of disease risk, and are often considerable simplifications of complex interrelationships. This may be particularly important when attempting to infer causality in patterns of co-infection through pathogen-facilitation. METHODS: We describe analyses of cross-sectional data using structural equation models (SEMs), a contemporary advancement on traditional regression approaches, based on our study system of feline gammaherpesvirus (FcaGHV1) in domestic cats. RESULTS: SEMs strongly supported a latent (host phenotype) variable associated with FcaGHV1 exposure and co-infection risk, suggesting these individuals are simply more likely to become infected with multiple pathogens. However, indications of pathogen-covariance (potential facilitation) were also variably detected: potentially among FcaGHV1, Bartonella spp and Mycoplasma spp. CONCLUSIONS: Our models suggest multiple exposures are primarily driven by host phenotypic traits, such as aggressive male phenotypes, and secondarily by pathogen-pathogen interactions. The results of this study demonstrate the application of SEMs to understanding epidemiological processes using observational data, and could be used more widely as a complementary tool to understand complex cross-sectional information in a wide variety of disciplines
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Closing the gap on causal processes of infection risk from cross-sectional data: structural equation models to understand infection and co-infection
Background: Epidemiological studies of disease exposure risk are frequently based on observational, cross-sectional data, and use statistical approaches as crucial tools for formalising causal processes and making predictions of exposure risks. However, an acknowledged limitation of traditional models is that the inferred relationships are correlational, cannot easily distinguish direct from indirect determinants of disease risk, and are often considerable simplifications of complex interrelationships. This may be particularly important when attempting to infer causality in patterns of co-infection through pathogen-facilitation.
Methods: We describe analyses of cross-sectional data using structural equation models (SEMs), a contemporary advancement on traditional regression approaches, based on our study system of feline gammaherpesvirus (FcaGHV1) in domestic cats.
Results: SEMs strongly supported a latent (host phenotype) variable associated with FcaGHV1 exposure and co-infection risk, suggesting these individuals are simply more likely to become infected with multiple pathogens. However, indications of pathogen-covariance (potential facilitation) were also variably detected: potentially among FcaGHV1, Bartonella spp and Mycoplasma spp.
Conclusions: Our models suggest multiple exposures are primarily driven by host phenotypic traits, such as aggressive male phenotypes, and secondarily by pathogen-pathogen interactions. The results of this study demonstrate the application of SEMs to understanding epidemiological processes using observational data, and could be used more widely as a complementary tool to understand complex cross-sectional information in a wide variety of disciplines.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by BioMed Central. The published article can be found at: http://www.parasitesandvectors.com
Closing the gap on causal processes of infection risk from cross-sectional data: structural equation models to understand infection and co-infection
Felis catus gammaherpesvirus 1; a widely endemic potential pathogen of domestic cats
AbstractFelis catus gammaherpesvirus 1 (FcaGHV1), recently discovered in the USA, was detected in domestic cats in Australia (11.4%, 95% confidence interval 5.9–19.1, n=110) and Singapore (9.6%, 95% confidence interval 5.9–14.6, n=176) using qPCR. FcaGHV1 qPCR positive cats were 2.8 times more likely to be sick than healthy. Risk factors for FcaGHV1 detection included being male, increasing age and coinfection with pathogenic retroviruses, feline immunodeficiency virus (FIV) or feline leukaemia virus. FcaGHV1 DNA was detected in multiple tissues from infected cats with consistently high virus loads in the small intestine. FcaGHV1 viral load was significantly higher in FIV-infected cats compared with matched controls, mimicking increased Epstein–Barr virus loads in human immunodeficiency virus-infected humans. FcaGHV1 is endemic in distant geographic regions and is associated with being sick and with coinfections. Horizontal transmission of FcaGHV1 is supported, with biting being a plausible route. A pathogenic role for FcaGHV1 in domestic cats is supported
Novel Gammaherpesviruses in North American Domestic Cats, Bobcats, and Pumas: Identification, Prevalence, and Risk Factors
UnlabelledGammaherpesviruses (GHVs) are a diverse and rapidly expanding group of viruses associated with a variety of disease conditions in humans and animals. To identify felid GHVs, we screened domestic cat (Felis catus), bobcat (Lynx rufus), and puma (Puma concolor) blood cell DNA samples from California, Colorado, and Florida using a degenerate pan-GHV PCR. Additional pan-GHV and long-distance PCRs were used to sequence a contiguous 3.4-kb region of each putative virus species, including partial glycoprotein B and DNA polymerase genes. We identified three novel GHVs, each present predominantly in one felid species: Felis catus GHV 1 (FcaGHV1) in domestic cats, Lynx rufus GHV 1 (LruGHV1) in bobcats, and Puma concolor GHV 1 (PcoGHV1) in pumas. To estimate infection prevalence, we developed real-time quantitative PCR assays for each virus and screened additional DNA samples from all three species (n = 282). FcaGHV1 was detected in 16% of domestic cats across all study sites. LruGHV1 was detected in 47% of bobcats and 13% of pumas across all study sites, suggesting relatively common interspecific transmission. PcoGHV1 was detected in 6% of pumas, all from a specific region of Southern California. The risk of infection for each host varied with geographic location. Age was a positive risk factor for bobcat LruGHV1 infection, and age and being male were risk factors for domestic cat FcaGHV1 infection. Further characterization of these viruses may have significant health implications for domestic cats and may aid studies of free-ranging felid ecology.ImportanceGammaherpesviruses (GHVs) establish lifelong infection in many animal species and can cause cancer and other diseases in humans and animals. In this study, we identified the DNA sequences of three GHVs present in the blood of domestic cats (Felis catus), bobcats (Lynx rufus), and pumas (Puma concolor; also known as mountain lions, cougars, and panthers). We found that these viruses were closely related to, but distinct from, other known GHVs of animals and represent the first GHVs identified to be native to these feline species. We developed techniques to rapidly and specifically detect the DNA of these viruses in feline blood and found that the domestic cat and bobcat viruses were widespread across the United States. In contrast, puma virus was found only in a specific region of Southern California. Surprisingly, the bobcat virus was also detected in some pumas, suggesting relatively common virus transmission between these species. Adult domestic cats and bobcats were at greater risk for infection than juveniles. Male domestic cats were at greater risk for infection than females. This study identifies three new viruses that are widespread in three feline species, indicates risk factors for infection that may relate to the route of infection, and demonstrates cross-species transmission between bobcats and pumas. These newly identified viruses may have important effects on feline health and ecology