Serosurvey for selected pathogens in hunter-killed pronghorns in western Nebraska

Exposure of pronghorns (Antilocapra americana) in western Nebraska in 1983 to selected livestock pathogens was examined by serology and attempted virus isolation. Antibodies were present to the agents of bluetongue, epizootic hemorrhagic disease, and bovine respiratory syncytial virus. There were no serologic reactors to Brucella, and attempts to isolate the viruses of bluetongue and epizootic hemorrhagic disease were negative.     

Serologic survey of selected pathogens in white-tailed and mule deer in western Nebraska

Exposure of free-ranging white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus) in western Nebraska to selected livestock pathogens was determined by serology and attempted virus isolation. Antibodies to bluetongue virus, epizootic hemorrhagic disease virus, and bovine respiratory syncytial virus were present in both species of deer. No serologic reactors to Brucella or Anaplasma were found. Attempts to isolate bluetongue virus were negative.     

Study of the antigenic structure of the E1 glycoprotein of the Venezuelan equine encephalomyelitis virus using monoclonal antibodies]

The collection of eight rat and mouse hybridomas secreting the high affinity monoclonal antibodies to glycoprotein E1 of the Venezuelan equine encephalomyelitis has been obtained. The antigenic structure of E1 protein has been studied with the use of these antibodies for the strains Trinidad, TC-83 and 230 of the virus. Antigenic map of glycoprotein E1 based on competition radioimmunoanalysis is proposed. Five sites are mapped including eight epitopes binding monoclonal antibodies. Antibodies to sites E1-1, E1-3 and E1-5 are crossreactive in interaction with the virus of Venezuelan equine encephalomyelitis, while antibodies to site E1-5 interact also with the virus of tick-borne encephalitis. Antibodies to site E1-1 possess the protective effect and lack the neutralizing effect in tissue cultures. Antibodies to all sites of E1 protein are devoid of ability to neutralize the Venezuelan equine encephalitis virus.     

A serologic survey of pronghorns in Alberta and Saskatchewan, 1970-1972.

To determine the exposure of free-ranging pronghorns (Antilocapra americana Ord) to selected pathogens, serum samples were obtained from 33 live-trapped animals from southwestern Saskatchewan in 1970, and from 26 and 51 animals from southeastern Alberta, in 1971 and 1972, respectively. Antibodies were found to the agents of parainfluenza 3, bovine virus diarrhea, eastern and western encephalomyelitis, infectious bovine rhinotracheitis and the chlamydial group. No serologic reactors were found to the agents of bluetongue, epizootic hemorrhagic disease, brucellosis, or leptospirosis (4 serotypes).     

Prevalence of selected zoonotic diseases in vertebrates from Haiti, 1972.

Vertebrate animals collected in Haiti in 1972 were tested for selected zoonotic diseases. No rabies virus or neutralizing (N) antibody was detected in bats (Artibeus jamaicensis). However, N antibody against St. Louis encephalitis, Western equine encephalitis (WEE), and Eastern equine encephalitis were detected in resident species of birds and WEE antibody in bats. No N antibody against Venezuelan equine encephalitis was found. The possible introduction by migratory birds and local transmission of these arboviruses is discussed.     

Venezuelan Equine Encephalitis Virus Activity in the Gulf Coast Region of Mexico, 2003–2010

Venezuelan equine encephalitis virus (VEEV) has been the causative agent for sporadic epidemics and equine epizootics throughout the Americas since the 1930s. In 1969, an outbreak of Venezuelan equine encephalitis (VEE) spread rapidly from Guatemala and through the Gulf Coast region of Mexico, reaching Texas in 1971. Since this outbreak, there have been very few studies to determine the northward extent of endemic VEEV in this region. This study reports the findings of serologic surveillance in the Gulf Coast region of Mexico from 2003–2010. Phylogenetic analysis was also performed on viral isolates from this region to determine whether there have been substantial genetic changes in VEEV since the 1960s. Based on the findings of this study, the Gulf Coast lineage of subtype IE VEEV continues to actively circulate in this region of Mexico and appears to be responsible for infection of humans and animals throughout this region, including the northern State of Tamaulipas, which borders Texas.     

Serologic survey for selected infectious disease agents in swift and kit foxes from the western United States

A serologic survey of swift fox (Vulpes velox) and kit fox (V. macrotis) from the western USA was conducted for 12 infectious diseases. Samples from swift fox were collected between 1987 and 1992 from Colorado (n = 44), Kansas (n = 10), and Wyoming (n = 9). Samples from kit fox were collected in California (n = 86), New Mexico (n = 18), Utah (n = 9), and Arizona (n = 6). Overall antibody prevalence rates were 33 of 110 (30%) for canine parvovirus (CPV), 9 of 72 (13%) for canine distemper virus (CDV), 23 of 117 (20%) for vesicular stomatitis New Jersey, 16 of 117 (14%) for vesicular stomatitis Indiana, six of 117 (5%) for Cache Valley virus, five of 117 (4%) for Jamestown Canyon virus, one of 97 (1%) for rabies virus, one of 117 (1%) for Colorado tick fever virus, and one of 117 (1%) for western equine encephalitis virus. In addition, antibodies were not found to Yersinia pestis, Francisella tularensis, and Borrelia burgdorferi in serum from 25 Colorado swift fox. Adult swift fox from Colorado had serologic evidence of exposure to CPV more often than juveniles. No juvenile swift fox from Colorado had serum antibodies to CDV. There were season-specific differences in serum antibody prevalence for CPV for swift fox from Colorado. No viruses were isolated from ectoparasites or fox from Colorado.     

Antibodies to bluetongue and epizootic hemorrhagic disease viruses from white-tailed deer blood samples dried on paper strips.

The feasibility of using dried blood samples for serologic testing of white-tailed deer (Odocoileus virginianus) for antibodies to bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) was tested with matched samples of serum and eluted dried whole blood. Results from matched serum virus neutralization (SN) tests indicated that a 1-ml elution from a 1- x 2-cm section of filter paper strip containing dried blood approximated a 1:10 serum dilution. Neutralizing antibody titers detected from 34 matched titrations of serum and dried blood samples were equivalent in 25 (74%) titrations and were within a single dilution in the remaining nine (26%) titrations. Eluted blood samples from SN-positive deer, however, did not produce detectable precipitin lines on agar gel immunodiffusion tests for antibodies to either BTV or EHDV. In a trial using serum and dried blood samples from 108 hunter-killed deer from five locations in Georgia (USA), antibody prevalence and serotype distribution results were similar. Use of dried blood samples for serologic testing for antibodies to BTV and EHDV provides a reliable alternative to serum but should be considered only when serum collection is not feasible.     

Experimental bluetongue disease in white-tailed deer

Nine white-tailed deer and six sheep were experimentally exposed to the California BTV-8 strain of bluetongue virus. The infections were fatal for seven of the nine deer. An additional deer died from exposure to an isolate of bluetongue virus from bighorn sheep. Clinical signs and lesions of bluetongue in deer were described. The incubation period, signs and lesions of bluetongue and epizootic hemorrhagic disease of deer appear to be similar. Virus isolations were made from the blood and a variety of tissues of exposed deer and identified as bluetongue virus. Neutralizing antibodies were detected in all of the convalescent sera.     

Infectious disease survey of Rio Grande wild turkeys in the Edwards Plateau of Texas

State wildlife agencies have translocated thousands of wild turkeys (Meleagris gallopavo) since the 1930s to reestablish this species. Because of threats to the domestic poultry industry and wild birds, screening for selected infectious agents has become routine since the early 1980s. One of the principal sources for Rio Grande wild turkeys (M. gallopavo intermedia) for translocation purposes was the Edwards Plateau of Texas (USA). Unfortunately, turkey abundance has declined in the southern Edwards Plateau since the late 1970s. Surprisingly few studies have addressed wild turkeys in this region, perhaps reflecting its status as the heart of Rio Grande turkey range. We surveyed 70 free-living Rio Grande wild turkeys from Bandera and Kerr counties, Texas, for evidence of exposure to Salmonella typhimurium, S. pullorum, Mycoplasma gallisepticum, M. meleagridis, M. synoviae, Chlamydophila psittaci, and the avian influenza, Newcastle disease, turkey corona, and reticuloendotheliosis viruses. Of these, 80% (56) were seropositive for both M. gallisepticum and M. synoviae on the serum plate antigen test. Ten of these individuals (14% of total) were positive for M. synoviae by hemagglutination inhibition testing. All other serologic tests were negative. Two adult females sampled in Kerr County, whose body mass was significantly less than that of other adult females trapped in the area, tested positive for reticuloendotheliosis virus (REV) proviral DNA on polymerase chain reaction. Reticuloendotheliosis virus was isolated from one of these individuals. The pathogenesis, transmission, and/or population-level influences of M. gallisepticum, M. synoviae, and REV in Rio Grande wild turkeys deserves further study.     

Serological survey for potential disease agents of free-ranging cervids in six selected national parks from Germany

A total of 164 blood samples, collected from free-ranging red deer (Cervus elaphus), roe deer (Capreolus capreolus) and fallow deer (Dama dama) in six German national parks (NP) between 2000 and 2002, were assayed for antibodies against nine viral disease agents. Antibodies were only detected against the alpha-herpesviruses; specifically, bovine herpesvirus-1 (BHV-1) (22 of 157, 14%), cervid herpesvirus-1 (17 of 157, 10.8%), and caprine herpesvirus-1 (11 of 159, 6.9%). Titers ranged from 4 to 102. Most of the seropositive sera, and those with the highest antibody titers, were from red and roe deer in the Harz and Hochharz NP, which are connected and allow migration between the two. The distribution and specificity of antibodies detected in individual deer suggests that the three alpha-herpesviruses are circulating in these deer populations. No antibodies were detected against bovine viral diarrhea virus, epizootic hemorrhagic disease virus, bovine leukemia virus, bluetongue virus, foot-and-mouth disease virus, or sheep and goat poxvirus.     

Serologic survey for pathogens potentially affecting pronghorn (Antilocapra americana) fawn recruitment in Arizona, USA

During the 1990s, pronghorn (Antilocapra americana) populations declined in Arizona, USA. To investigate potential causes of decline, we collected blood samples from hunter-harvested male pronghorn from 2001 to 2003 on four Arizona sites. Sera were tested for antibody to parainfluenza virus type 3 (PI3), bovine viral diarrhea virus, infectious bovine rhinotracheitis virus, bovine respiratory syncytial virus, epizootic hemorrhagic disease virus (EHDV), bluetongue virus (BTV), and Chlamydia psittaci. Antibody against PI3 was found in 33% of the samples, whereas antibody against BTV/EHDV was found in 77%. Antibodies to other pathogens were found at low prevalence rates. Although pronghorn decline in Arizona is probably not directly related to disease, potential reproductive effects of BTV/EHDV and PI3 infection on pronghorn in Arizona merit further study.     

Resistance to Alpha/Beta Interferons Correlates with the Epizootic and Virulence Potential of Venezuelan Equine Encephalitis Viruses and Is Determined by the 5′ Noncoding Region and Glycoproteins

We compared the alpha/beta interferon (IFN-α/β) sensitivities of the TC-83 vaccine strain and 24 enzootic and epizootic Venezuelan equine encephalitis (VEE) isolates. The IFN-resistant or -sensitive phenotype correlated well with epizootic or enzootic potential. IFN-α/β resistance of Trinidad donkey (TRD) virus correlated with virulence determinants in the 5′ noncoding region and glycoproteins. Infection of mice lacking a functional IFN system with the IFN-sensitive TC-83 virus resulted in disease equivalent to that produced by the virulent, IFN-resistant TRD virus, further demonstrating that IFN resistance contributes to VEE virus virulence and is a biological marker of epizootic potential.     

Generation and characterization of closely related epizootic and enzootic infectious cDNA clones for studying interferon sensitivity and emergence mechanisms of Venezuelan equine encephalitis virus

Venezuelan equine encephalitis virus (VEEV) is a reemerging pathogen and a continuing threat to humans and equines in the Americas. Identification of the genetic determinants that enable epizootic VEEV strains to arise and exploit equines as amplification hosts to cause widespread human disease is pivotal to understanding VEE emergence. The sensitivity to murine alpha/beta interferon-mediated antiviral activity was previously correlated to the epizootic phenotype of several VEEV strains. Infectious cDNA clones were generated from an epizootic subtype IC VEEV strain (SH3) isolated during the 1992 Venezuelan outbreak and a closely related enzootic, sympatric subtype ID strain (ZPC738). These VEEV strains had low-cell-culture-passage histories and differed by only 12 amino acids in the nonstructural and structural proteins. Rescued viruses showed similar growth kinetics to their parent viruses in several cell lines, and murine infections resulted in comparable viremia and disease. Unlike what was found in other studies of epizootic and enzootic VEEV strains, the sensitivities to murine alpha/beta interferon did not differ appreciably between these epizootic versus enzootic strains, calling into question the reliability of interferon sensitivity as a marker of epizootic potential.     

Disease survey of free-ranging grey brocket deer (Mazama gouazoubira) in the Gran Chaco, Bolivia

Samples from 17 free-ranging hunter-killed grey brocket deer (Mazama gouazoubira) in the Gran Chaco, Bolivia, were collected during June-August 1999. All 17 deer appeared to be in good condition at the time of death. Gross necropsies were performed, serum was collected for serologic evaluation of selected infectious disease agents, and feces and ectoparasites were collected for evaluation of internal and external parasites. Serologic tests were positive for antibodies against bovine respiratory syncytial virus and four Leptospira interrogans serovars, with questionable results for epizootic hemorrhagic disease virus serotypes 1 and 2. No antibodies were detected to Anaplasma marginale, Babesia bigemina, Babesia bovis, Babesia odocoilei, bluetongue virus (serotypes 2, 10, 11, 13, and 17), bovine viral diarrhea virus, Brucella abortus, foot-and-mouth disease virus, infectious bovine rhinotracheitis virus, Mycobacterium avium subsp. paratuberculosis, and parainfluenza-3 virus. Sixty-four percent (7/11) of the deer had endoparasites. Amblyomma spp. ticks were found on seven deer, flies of the family Hippoboscidae on six deer, and lice on six deer.     

Eastern equine encephalitis in the United States, 1971: Past and prologue

During 1971, surveillance for equine encephalitis in the United States was increased due to an epizootic of Venezuelan equine encephalomyelitis. Of 1,982 specimens from 1,551 equines, 76 isolates of eastern equine encephalitis (EEE) virus were recovered from 67 individuals. The virus was isolated from 50/176 brains, 8/74 spleens, 14/1,127 sera, and 4/147 whole bloods from infected equines in 12 of the 31 states bounded by or east of the Mississippi River and in Texas and Iowa; no specimens were received from 9 of these 31 states. Thus, EEE virus was isolated from equines in 12 of 22 of these states. Determinations of antibody to EEE and western equine encephalitis (WEE) viruses indicated a relatively high prevalence of infection with EEE virus in the eastern USA and similarly high prevalence of antibody to WEE virus in the western USA. These data indicate that equine infections with EEE virus in the eastern USA are considerably more common than previous surveillance data have suggested. Increased surveillance and submission of specimens to diagnostic laboratories for diagnosis of EEE virus infections in equines are suggested so that a greater proportion of the thousands of unspecified equine encephalitis cases occurring in the United States each year can be laboratory confirmed.     

Serosurveillance for Livestock Pathogens in Free-Ranging Mule Deer (Odocoileus hemionus)

Routine disease surveillance has been conducted for decades in mule deer (Odocoileus hemionus) in California for pathogens shared between wildlife and domestic ruminants that may have implications for the animal production industry and wildlife health. Deer sampled from 1990 to 2007 (n = 2,619) were tested for exposure to six pathogens: bluetongue virus (BTV), epizootic hemorrhagic disease virus (EHDV), bovine viral diarrhea virus (BVDV), Leptospira spp., Anaplasma spp. and Brucella spp. We evaluated the relationship between exposure to these pathogens and demographic risk factors to identify broad patterns in seroprevalence across a large temporal and spatial scale. The overall seroprevalence for the entire study period was 13.4% for BTV, 16.8% for EHDV, 17.1% for BVDV, 6.5% for Leptospira spp., 0.2% for Brucella spp., and 17% for Anaplasma spp. Antibodies against BTV and EHDV were most prevalent in the deer populations of southern California. Antibodies against Leptospira spp. and Anaplasma spp. were most prevalent in coastal and central northern California whereas antibodies against BVDV were most prevalent in central-eastern and northeastern California. The overall seroprevalence for Anaplasma spp. was slightly lower than detected in previous studies. North and central eastern California contains large tracts of federal land grazed by livestock; therefore, possible contact between deer and livestock could explain the high BVDV seroprevalence found in these areas. Findings from this study will help to establish baseline values for future comparisons of pathogen exposure in deer, inform on long-term trends in deer population health and provide relevant information on the distribution of diseases that are shared between wildlife and livestock.     

Vector infection determinants of Venezuelan equine encephalitis virus reside within the E2 envelope glycoprotein

Epizootic subtype IAB and IC Venezuelan equine encephalitis viruses (VEEV) readily infect the epizootic mosquito vector Aedes taeniorhynchus. The inability of enzootic subtype IE viruses to infect this mosquito species provides a model system for the identification of natural viral determinants of vector infectivity. To map mosquito infection determinants, reciprocal chimeric viruses generated from epizootic subtype IAB and enzootic IE VEEV were tested for mosquito infectivity. Chimeras containing the IAB epizootic structural gene region and, more specifically, the IAB PE2 envelope glycoprotein E2 precursor gene demonstrated an efficient infection phenotype. Introduction of the PE2 gene from an enzootic subtype ID virus into an epizootic IAB or IC genetic backbone resulted in lower infection rates than those of the epizootic parent. The finding that the E2 envelope glycoprotein, the site of epitopes that define the enzootic and epizootic subtypes, also encodes mosquito infection determinants suggests that selection for efficient infection of epizootic mosquito vectors may mediate VEE emergence.     

Antibodies to bluetongue and epizootic hemorrhagic disease viruses in a barrier island white-tailed deer population.

From 1981 through 1989, serum samples from 855 white-tailed deer (Odocoileus virginianus) from Ossabaw Island, Georgia (USA), were tested for antibodies to bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). During this period, prevalence of precipitating antibodies to BTV and EHDV as determined by agar gel immunodiffusion (AGID) tests decreased from 74% to 3% and from 34% to 1%, respectively. Antibodies were detected in serum samples from 0.5-yr-old deer only during 1981, 1982, and 1983, and with few exceptions, positive serological results after 1983 were restricted to older age classes. A decrease in prevalence of precipitating antibodies to BTV and EHDV in age classes exposed during 1981 indicates that AGID results from white-tailed deer populations underestimate the extent of previous exposure to these viruses. Serum neutralization test results from AGID-positive deer indicated that BTV 11 was the principal serotype responsible for infections during 1981. Since 1983, this serotype has been replaced by BTV 13; however, there has been a low level of transmission within the herd. Infection with EHDV 2 appeared most prevalent during 1982; as with BTV 13, there has been limited transmission in this high density deer population since 1983.     

Exposure of red knots (Calidris canutus rufa) to select avian pathogens; Patagonia, Argentina

As part of the shorebird surveillance, Red Knots (Calidris canutus rufa) were sampled in two Patagonian sites in Argentina, Río Grande and San Antonio Oeste, during 2005-2006. Cloacal swabs and serum samples were collected from 156 birds and tested by virus isolation (Newcastle disease virus), polymerase chain reaction (PCR; avian influenza virus and Plasmodium/Hemoproteus), and for antibodies to St. Louis encephalitis virus. All test results were negative.