Evidence of SARS-CoV-2 Antibody in Mississippi White-Tailed Deer.

Background: Early detection and monitoring of SARS-CoV-2 infections in animal populations living in close proximity to humans is crucial for preventing reverse zoonosis of new viral strains. Evidence accumulated has revealed widespread SARS-CoV-2 infection among white-tailed deer (WTD), (Odocoileus virginianus) populations in the United States except in the southeast region. Therefore, the objective was to conduct surveillance for evidence of SARS-CoV-2 infection among WTD in Mississippi. Materials and Methods: Blood, kidney tissues, and nasal swab samples were collected in 17 counties from hunter-harvested deer during 2021-2022 and 2022-2023.Samples of kidney tissue were collected to evaluate for detecting antibody as a possible alternative to blood that is not always available from dead WTD. Nasal swab samples were tested for SARS-CoV-2 viral RNA by a RT-PCR assay. Sera and kidney tissue samples were tested for SARS-CoV-2 antibody by an enzyme-linked immunoassay (ELISA) and sera by a plaque reduction neutralization test (PRNT80). Results: The results of testing sera and kidney homogenate samples provided the first evidence of SARS-CoV-2 infection among WTD in Mississippi. The infection rate during 2021-2022 was 67% (10/15) based on the detection of neutralizing antibody by the PRNT80 and 26%(16/62) based on the testing of kidney tissue homogenates by an ELISA, and viral RNA was detected in 25% (3/12) of nasal swab samples. In 2022 to 2023, neutralizing antibody was detected in 62% (28/45) of WTD serum samples. In contrast, antibodies were not detected in 220 kidney homogenates by an ELISA nor was viral RNA detected in 220 nasal swab samples. Evidence of WTD activity was common in urban areas during the survey. Conclusion: Overall, the findings documented the first SARS-CoV-2 infection among WTD in Mississippi and showed that WTD commonly inhabited urban areas as a possible source of acquiring infection from humans infected with this virus.

Genomic Analysis of Aedes aegypti in the Northern Chihuahuan Desert of Texas and Mexico.

Background: Aedes aegypti, is the primary vector of dengue, Chikungunya, Zika, and yellow fever viruses. Both natural and human-impacted landscapes have selective pressures on Ae. aegypti, resulting in strong genomic structure even within close geographical distances. Materials and Methods: We assess the genetic structure of this medically important mosquito species at the northern leading edge of their distribution in Southwestern USA. Ae. aegypti were collected during 2017 in the urban communities of El Paso and Sparks, Texas (USA) and in the city of Ciudad Juárez, Mexico. Results: Thousands of nuclear loci were sequenced across 260 captured Ae. aegypti. First, we recovered the genetic structure of Ae. aegypti following geography, with all four major collection communities being genetically distinct. Importantly, we found population structure and genetic diversity that suggest rapid expansion through active-short distance dispersals, with Anapra being the likely source for the others. Next, tests of selection recovered eight functional genes across six outliers: calmodulin with olfactory receptor function; the protein superfamily C-type lectin with function in mosquito immune system and development; and TATA box binding protein with function in gene regulation. Conclusion: Despite these populations being documented in the early 2000s, we find that selective pressures on specific genes have already occurred and likely facilitate Ae. aegypti range expansion.

Evaluation of a Combined Live Attenuated Vaccine against Lumpy Skin Disease, Contagious Bovine Pleuropneumonia and Rift Valley Fever.

The use of effective vaccines is among the most important strategies for the prevention and progressive control of transboundary infectious animal diseases. However, the use of vaccine is often impeded by the cost, a lack of cold chains and other factors. In resource-limited countries in Africa, one approach to improve coverage and reduce cost is to vaccinate against multiple diseases using combined vaccines. Therefore, the objective of this study was to evaluate a combined vaccine for the prevention and control of Lumpy Skin Disease (LSD), Contagious Bovine Pleuropneumonia (CBPP) and Rift Valley fever (RVF). The LSD and CBPP were formulated as a combined vaccine, and the RVF was formulated separately as live attenuated vaccines. These consisted of a Mycoplasma MmmSC T1/44 strain that was propagated in Hayflick-modified medium, RVF virus vaccine, C13T strain prepared in African green monkey cells (Vero), and the LSDV Neethling vaccine strain prepared in primary testis cells. The vaccines were tested for safety via the subcutaneous route in both young calves and pregnant heifers with no side effect, abortion or teratogenicity. The vaccination of calves induced seroconversions for all three vaccines starting from day 7 post-vaccination (PV), with rates of 50% for LSD, 70% for CBPP and 100% for RVF, or rates similar to those obtained with monovalent vaccines. The challenge of cattle vaccinated with the LSD/CBPP and the RVF vaccine afforded full protection against virulent strains of LSDV and RVFV. A satisfactory level of protection against a CBPP challenge was observed, with 50% of protection at 6 months and 81% at 13 months PV. A mass vaccination trial was performed in four regions of Burkina Faso that confirmed safety and specific antibody responses induced by the vaccines. The multivalent LSD/CBPP+RVF vaccine provides a novel and beneficial approach to the control of the three diseases through one intervention and, therefore, reduces the cost and improves vaccination coverage.

Serosurveillance for Severe Acute Respiratory Syndrome Coronavirus 2 Antibody in Feral Swine and White-Tailed Deer in Texas.

Background: Serological evidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been reported in white-tailed deer (WTD) in the United States and Canada. Even though WTD are susceptible to SARS-CoV-2 infection, there is no evidence of infection by this virus in other mammalian species that might interact with WTD in nature. Similar to WTD, feral swine are widely distributed and generally occupy the same range as WTD in Texas. The objective of this study was to determine the prevalence of SARS-CoV-2 neutralizing antibody in WTD during 2020 and 2021 and determine the prevalence of SARS-CoV-2 neutralizing antibody in feral swine during 2018 (prepandemic period) and from March 2020 to February 2021 (pandemic period) in Travis County, Texas. Materials and Methods: Sera samples were collected from hunter-killed WTD and feral swine during the prepandemic and pandemic period and tested for SARS-CoV-2 antibody by a plaque reduction neutralization assay in Vero cells. Results: SARS-CoV-2 antibody was not detected in any of the 166 feral swine sera samples, including 24 samples collected during the prepandemic and 142 samples collected during the pandemic period. Furthermore, SARS-CoV-2 antibody was not detected in the 115 WTD samples collected during late 2020, but antibody was detected in WTD in early 2021. Conclusions: The results indicated that SARS-CoV-2 infection of WTD occurred during early 2021 in Travis County, Texas, but serological evidence of SARS-CoV-2 infection was not detected in the feral swine samples collected from the same locality and during the same time period of the collection of WTD samples.

Clinical and epidemiological characteristics of probable cases of congenital Zika syndrome and dengue antibody levels, Tuxtla Gutierrez, Chiapas, Mexico

Introduction: We previously found that the occurrence of congenital Zika syndrome was under-reported in Mexico. It was postulated that high dengue virus antibody levels found at the population-level in endemic countries might have contributed to the occurrence of the regional pandemic of Zika disease. A case series of suspected cases of congenital Zika syndrome in a maternity hospital in Tuxtla Gutierrez, Chiapas, Mexico was assembled to assess why they were not reported and to explore the hypothesis of dengue virus antibody-dependent enhancement of Zika disease. Methods: We used a quantitative approach to describe clinical and imaging records and used data from interviews of a total of 13 suspected cases of congenital Zika syndrome. We also quantitated dengue 1 and 2 antibodies using an 80% plaque reduction neutralization test of sera specimens obtained from the mothers of these 13 cases and compared them to those of a group of mothers who delivered normal newborns in the same hospital. Results: Only one of the suspected cases was laboratory-confirmed because appropriate specimens were not collected from the newborns as required by the case definition. We found 1) microcephaly, 2) hypoplasia/hypogeneses, thinning or absence of brain structures, 3) multiple birth defects, 4) calcifications, and cysts, 5) meningocele/encephalocele, and 6) hydrocephalus in 100 %, 76.9 %, 38.5 %, 38.5 %, 30.8 %, and 23.1 %, respectively of the case series. The cases clustered geographically, and 77 % occurred between May 2016 to March 2017 and recalled or were told by a doctor they had Zika fever. There was a four-fold increased risk of congenital Zika syndrome among those with dengue 1 antibody as compared to those with dengue 2 antibodies (odds ratio = 3.6; 95 % confidence interval: 0.7, 20.5), reaching only borderline statistical significance. Conclusions: We found in the largest maternal facility of the capital of the State of Chiapas, in Mexico, that only 7.7 % of suspected cases were confirmed, and that the rather complex requirement of cerebrospinal fluid specimens or serological specimens of newborns for suspected cases of congenital Zika syndrome used during the pandemic resulted in low sensitivity of the surveillance system. The finding of higher levels of dengue 1 than dengue 2 antibodies in cases than the referent population, requires further evaluation and may suggest a role for dengue antibody-dependent response in Zika disease.

Introducción: Previamente los autores habían encontrado evidencia de sub-notificación de la ocurrencia del síndrome congénito por Zika en México. Se ha postulado que niveles elevados de anticuerpos contra los virus del dengue a nivel poblacional en los países endémicos hubiese contribuido a la ocurrencia de la pandemia regional de enfermedad por Zika. Ensamblamos una serie de casos sospechosos de síndrome congénito por Zika en un hospital de maternidad en Tuxtla Gutiérrez, Chiapas, México, para evaluar por qué no fueron notificados y explorar la hipótesis de enfermedad por Zika incrementada por anticuerpos anti-dengue. Métodos: Utilizamos un enfoque cuantitativo para describir 13 casos sospechosos de síndrome congénito por revisamos registros clínicos e imágenes, entrevistas. También cuantificamos los niveles de anticuerpos para los virus dengue 1 y 2 en suero de las madres de los casos comparados con los de mujeres que tuvieron recién nacidos normales en el mismo hospital. Resultados: Solamente uno de los 12 casos sospechosos fue confirmado por laboratorio, porque en los demás no se recolectaron especímenes adecuados de los neonatos como lo requería la definición de casos. Encontramos 1) microcefalia, 2) hipoplasia y adelgazamiento de las estructuras cerebrales, 3) malformaciones múltiples, 4) calcificaciones o quistes, 5) meningocele/encefalocele, y 6) hidrocefalia en: 100 %, 76.9 %, 38.5 %, 38.5 %, 30.8 %, y 23.1 %, en ese orden entre los casos sospechosos. Los casos se aglutinaron geográficamente y 77 % ocurrieron entre Mayo del 2016 y Marzo del 2017, y sus madres recordaban que tuvieron o que un profesional de la salud les dijo que tuvieron fiebre por Zika. Encontramos un incremento de casi 4 veces en el riesgo de síndrome congénito por Zika para aquellos con altos niveles de anticuerpos anti-dengue 1 comparado con anticuerpos anti-dengue 2 (cociente de suertes = 3.6; intervalo de confianza del 95 %: 0.7, 20.5), alcanzando solamente una significancia estadística limítrofe. Conclusiones: Encontramos en el establecimiento de atención a la maternidad más grande en la capital de Chiapas, México, que solamente 7.7 % de los casos sospechosos de síndrome congénito por Zika fueron confirmados y que los relativamente complejos requerimientos de la definición de casos de muestras serológicas o de líquido cefalorraquídeo resultó en una baja sensibilidad del sistema de vigilancia. El hallazgo de niveles más altos de anticuerpos a dengue 1 que dengue 2 requiere más evaluación y pudiera sugerir un papel de la respuesta dependiente de anticuerpos al dengue en Zika.

Attenuation and genetic characteristics of a Moroccan strain of Camel pox virus.

Camel pox (CML) is a widespread infectious viral disease of camels that causes huge economic losses to the camel industry. In this study, a local strain of Camel pox virus (CMLV) was attenuated by 175 serial passages in Vero cells and the residual pathogenicity and infectivity were tested in naïve camels at 120, 150 and 175 passage levels. Also, the safety and immunogenicity of the 175th passage were evaluated in camels using a dose of 104.0 Tissue Culture Dose 50% (TCID50) and monitored for up to one-year post vaccination (pv) for neutralizing antibody. Seroconversion was noted at day 14 pv with neutralizing antibody titers ranging from 0.5 and 1.6 logs over the one-year of the study. Among 8 camels inoculated with the P175 strain, 4 were challenged at 12-month pv with 105.7 TCID50/ml of the original virulent CMLV and complete protection was recorded in all animals. Whole genome sequencing detected six mutations in the original CMLV strain that were not present in the attenuated 175th passage of this strain. Overall, the findings of this study indicated that the 175th passage of the CMLV was attenuated, safe and afforded protection to camels against virulent CMLV, and is therefore, a promising vaccine candidate for the prevention of CML in camels.

Estimation of the Minimal Rift Valley Fever Virus Protective Neutralizing Antibody Titer in Human Volunteers Immunized with MP-12 Vaccine Based on Protection in a Mouse Model of Disease.

The Rift Valley fever virus (RVFV) MP-12 vaccine is a promising human and veterinary vaccine. Although the vaccine elicited neutralizing antibody (nAb) in human volunteers, the minimal antibody titer that is needed to afford protection is unknown. Therefore, this study was conducted to determine the minimal nAb titer elicited by the RVFV MP-12 vaccine in human volunteers that protected mice against lethal RVFV challenge as a surrogate assessment of the protective efficacy of the vaccine. Among volunteers who were vaccinated with the MP-12 vaccine during a phase II trial, sera with antibody titers of 1:20 collected 5 years post-vaccination (PV), 1:40 titer collected 2 years PV, and 1:80 titer collected 1 year PV was passively transferred to groups of BALB/c mice. Blood samples were obtained 1 day after passive transfer to determine the RVFV neutralizing nAb titer before challenge with pathogenic RVFV (strain ZH501). Our results indicated that 1 day after passive transfer of the immune sera, an approximate 4-fold reduction in circulating nAb titers was detected in the mice. The presence of RVFV nAb titers in the range of 1:5 to 1:20 were generally protective (75-100% survival). These results suggested that circulating titers of 1:5 or higher offer a high degree of protection by MP-12-elicited antibody in human volunteers. Also, the findings highlighted the value of using the BALB/c mouse RVFV challenge model as a surrogate for evaluating the protective nAb responses elicited by MP-12 and possible use for evaluating the efficacy of other RVFV vaccine candidates.

A Branched and Double Alpha-Gal-Bearing Synthetic Neoglycoprotein as a Biomarker for Chagas Disease.

Chagas disease (CD) is caused by the parasite Trypanosoma cruzi and affects 6-7 million people worldwide. The diagnosis is still challenging, due to extensive parasite diversity encompassing seven genotypes (TcI-VI and Tcbat) with diverse ecoepidemiological, biological, and pathological traits. Chemotherapeutic intervention is usually effective but associated with severe adverse events. The development of safer, more effective therapies is hampered by the lack of biomarker(s) (BMKs) for the early assessment of therapeutic outcomes. The mammal-dwelling trypomastigote parasite stage expresses glycosylphosphatidylinositol-anchored mucins (tGPI-MUC), whose O-glycans are mostly branched with terminal, nonreducing α-galactopyranosyl (α-Gal) glycotopes. These are absent in humans, and thus highly immunogenic and inducers of specific CD anti-α-Gal antibodies. In search for α-Gal-based BMKs, here we describe the synthesis of neoglycoprotein NGP11b, comprised of a carrier protein decorated with the branched trisaccharide Galα(1,2)[Galα(1,6)]Galß. By chemiluminescent immunoassay using sera/plasma from chronic CD (CCD) patients from Venezuela and Mexico and healthy controls, NGP11b exhibited sensitivity and specificity similar to that of tGPI-MUC from genotype TcI, predominant in those countries. Preliminary evaluation of CCD patients subjected to chemotherapy showed a significant reduction in anti-α-Gal antibody reactivity to NGP11b. Our data indicated that NGP11b is a potential BMK for diagnosis and treatment assessment in CCD patients.

Etiologies of Acute Undifferentiated Febrile Illnesses in and near Iquitos from 1993 to 1999 in the Amazon River Basin of Peru.

The objective of this study was to determine the etiology of febrile illnesses among patients from October 1, 1993 through September 30, 1999, in the urban community of Iquitos in the Amazon River Basin of Peru. Epidemiological and clinical data as well as blood samples were obtained from consenting patients at hospitals, health clinics and private residences. Samples were tested for arboviruses in cell cultures and for IgM and IgG antibodies by ELISA. Blood smears were examined for malaria, and sera were tested for antibodies to Leptospira spp. by ELISA and microscopic agglutination. Among 6,607 febrile patients studied, dengue viruses caused 14.6% of the cases, and Venezuelan equine encephalitis virus caused 2.5%, Oropouche virus 1.0%, Mayaro virus 0.4%, and other arboviruses caused 0.2% of the cases. Also, 22.9% of 4,844 patients tested were positive for malaria, and of 400 samples tested, 9% had evidence of acute leptospirosis. Although the study was not designed to assess the importance of these pathogens as a cause of human morbidity in the total population, these results indicate that arboviruses, leptospirosis, and malaria were the cause of approximately 50% of the febrile cases. Although the arboviruses that were diagnosed can produce asymptomatic infections, our findings increased the overall understanding of the relative health burden of these infections, as well as baseline knowledge needed for designing and implementing further studies to better assess the health impact and threat of these pathogens in the Amazon Basin of Peru.

SARS-CoV-2 Neutralizing Antibodies in White-Tailed Deer from Texas.

Serological evidence of SARS-CoV-2 infection among white-tailed deer has been reported from Illinois, Michigan, Pennsylvania, and New York. This study was conducted to determine whether deer in Texas also had evidence of SARS-CoV-2 infection. Archived sera samples collected from deer in Travis County, Texas, during 2018, before and during the pandemic in 2021 were tested for neutralizing antibody to this virus by a standard plaque reduction neutralization assay. SARS-CoV-2 antibody was not detected in 40 deer sera samples collected during 2018, but 37% (20/54) samples collected in 2021 were positive for antibody. The seroprevalence rate between males and females differed significantly (p < 0.05) and the highest rate (82%) was detected in the 1.5-year-old animals. These findings extended the geographical range of prior SARS-CoV-2 infection among white-tailed deer in the United States and further confirm that infection was common among this species.

Evaluation of Two Serological Assays for Diagnosing Zika Virus Infection.

Zika virus (ZIKV) emerged and spread rapidly in South American countries during 2015. Efforts to diagnose ZIKV infection using serological tools were challenging in dengue-endemic areas because of antigenic similarities between both viruses. Here, we assessed the performance of an in-house developed IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA) and the plaque reduction neutralization test (PRNT) to diagnose ZIKV infection. Acute and convalescent paired serum samples from 51 patients who presented with clinical symptoms suggestive of an arbovirus illness in dengue-endemic areas of Honduras, Venezuela, Colombia and Peru were used in the assessment. Samples were tested for ZIKV, dengue and chikungunya virus using a variety of laboratory techniques. The results for the ZIKV-RNA screening and seroconversion detected by the microneutralization test were used to construct a composite reference standard. The overall sensitivity and specificity for the MAC-ELISA were 93.5% and 100.0%, respectively. Contrastingly, the overall sensitivity and specificity for the PRNT were 96.8% and 95.0%, respectively. Restricting the analysis according to IgM or neutralizing antibodies against dengue, the performances of both serological assays were adequate. The findings of this study reveal that the MAC-ELISA and PRNT would provide initial reliable laboratory diagnostic assays for ZIKV infection in dengue-endemic areas.

Characterization of a Dengue Virus Serotype 1 Isolated from a Patient in Ciudad Juarez, Mexico.

Dengue (DEN) is the most important human arboviral disease worldwide. Sporadic outbreaks of DEN have been reported since 1980 in urban communities located along the border in southeast Texas and northern Mexico. Other than the Rio Grande Valley region of TX, autochthonous transmission of DENV has not been reported from any other US border communities. As part of a surveillance program for arthropod-borne viruses in Ciudad Juarez, Mexico, during November 2015, a blood sample was obtained from a female patient who experienced an undifferentiated fever and arthralgia. The plasma of the sample was tested for virus in Vero-76 and C6/36 cells. DENV serotype 1 (DENV-1) was isolated in the C6/36 cells, and nucleotide sequencing of the envelope gene and full genome grouped the DENV-1 isolate in the Central America clade. The patient had not traveled outside of Ciudad Juarez, Mexico, thus suggesting DENV-1 infection was acquired in this community.

Surveillance of Trypanosoma cruzi infection in Triatomine vectors, feral dogs and cats, and wild animals in and around El Paso county, Texas, and New Mexico.

The causative agent of Chagas disease, Trypanosoma cruzi, is transmitted by triatomine vectors. The insect is endemic in the Americas, including the United States, where epidemiological studies are limited, particularly in the Southwestern region. Here, we have determined the prevalence of T. cruzi in triatomines, feral cats and dogs, and wild animals, the infecting parasite genotypes and the mammalian host bloodmeal sources of the triatomines at four different geographical sites in the U.S.-Mexico border, including El Paso County, Texas, and nearby cities in New Mexico. Using qualitative polymerase chain reaction to detect T. cruzi infections, we found 66.4% (n = 225) of triatomines, 45.3% (n = 95) of feral dogs, 39.2% (n = 24) of feral cats, and 71.4% (n = 7) of wild animals positive for T. cruzi. Over 95% of T. cruzi genotypes or discrete typing units (DTUs) identified were TcI and some TcIV. Furthermore, Triatoma rubida was the triatomine species most frequently (98.2%) collected in all samples analyzed. These findings suggest a high prevalence of T. cruzi infections among triatomines, and feral and wild animals in the studied sites. Therefore, our results underscore the urgent need for implementation of a systematic epidemiological surveillance program for T. cruzi infections in insect vectors, and feral and wild animals, and Chagas disease in the human population in the southwestern region of the United States.

Enhancement of Zika virus infection by antibodies from West Nile virus seropositive individuals with no history of clinical infection.

BACKGROUND: Recent outbreaks of Zika Virus (ZIKV) infection and associated microcephaly has raised multiple scientific questions. The close antigenic relatedness between flaviviruses makes diagnosis of specific infection difficult. This relatedness also raises the potential of Antibody Dependent Enhancement (ADE) via cross reactive antibodies to flaviviruses like West Nile Virus (WNV) and Dengue Virus (DENV). Asymptomatic WNV infections are endemic throughout the US creating a large proportion of the population that is seropositive for WNV antibodies. Whether these sero-positive individuals potentially carry ZIKV enhancing antibodies remains unknown. RESULTS: Serum samples obtained from human subjects with symptomatic or asymptomatic WNV infection from a WNV endemic region in Texas were tested for their ability to enhance or neutralize ZIKV infection. Sero-surveillance data demonstrated a ~ 7% prevalence for WNV antibodies in the population. Sera from both symptomatic and asymptomatic WNV seropositive donors effectively neutralized WNV and to some extent DENV infection. Interestingly, WNV+ sera failed to inhibit ZIKV while significantly enhancing infection. Conversely, ZIKV specific sera effectively neutralized ZIKV, with ADE only evident at lower concentrations. The enhancement of ZIKV via WNV antibody positive sera was likely due to non-neutralizing Envelope (E) antibodies as seen with monoclonal ZIKV E antibodies. CONCLUSIONS: Overall, our findings suggest that WNV antibodies in the sera significantly enhance ZIKV infection in Fc receptor positive cells with limited neutralization activity. Further studies in more relevant models of ADE will be needed to confirm the relevance of these findings in vivo.

Serosurvey for dengue virus infection among pregnant women in the West Nile virus enzootic community of El Paso Texas.

All 4 dengue viruses (DENV) cause sporadic outbreaks of human disease in the Rio Grande Valley along the US-Mexico border. In addition, West Nile virus (WNV) is enzootic in most border communities, and is the only arbovirus known to cause human disease in the El Paso, Texas community. In an effort to determine if DENV were also endemic in the El Paso community, a serosurvey was conducted among mothers at the time of delivery of their babies in selected hospitals. Cord-blood plasma samples obtained from mothers were tested for DENV antibody by an enzyme-linked immuno-sorbent assay (ELISA), plaque reduction neutralization test (PRNT) and a multiplex microsphere immunoassay. All DENV antibody positive plasma samples were also tested for WNV antibody by the same assays to consider the possibility that DENV antibody positive samples reflected WNV cross reactive antibody. The results indicated that 0.74% (11/1,472) of the mothers had a previous DENV infection and that 3.3% (48/1,472) had a previous WNV infection. Of these mothers, 0.20% (3/1,472) had antibody to both DENV and WNV as evidence of infection by both viruses. The results indicated that 0.2% (3/1472) of the mothers were positive for antibody to only WNV envelope, thus suggesting an undetermined flavivirus infection. Although 6 of the 11 DENV antibody positive mothers did not have a history of travel to a DENV endemic country, the findings of this survey provided further evidence of local transmission of WNV and suggested the possibility of focal autochthonous transmission of DENV in the El Paso community.

Serological Evidence of West Nile Virus Infection in White-Tailed Deer in Central Texas.

White-tailed deer (WTD) are abundant mammals widely distributed across the United States. As a result, WTD are considered to be excellent sentinels for detecting arboviral activity in certain geographic areas. Evidence of West Nile virus (WNV) antibody in WTD has been reported previously in several states. However, WNV infection in WTD has not been reported from Texas, where the incidence of human West Nile (WN) cases is among the highest in the United States. Therefore, the aim of this study was to determine the prevalence of WNV antibody in WTD in central Texas. Sera samples (n = 644) were collected from deer during the fall and winter in western Travis County, Texas from 2014 to 2018 and tested for WNV immunoglobulin G (IgG) antibody by an indirect enzyme-linked immunosorbent assay (ELISA). ELISA antibody-positive samples were further tested for WNV and St. Louis encephalitis virus (SLEV) antibodies by an 80% plaque-reduction neutralization tests (PRNT80). Overall, 9% (n = 58) and 0.31% (n = 2) of the deer samples had serological evidence of WNV and SLEV infections, respectively. WNV seroprevalence differed significantly by age (p < 0.05), but there was no significant difference between sex. Interestingly, 3.1% (n = 20) of the samples were positive for Flavivirus IgG antibody by ELISA, but negative for SLEV and WNV antibodies, suggesting that other Flaviviruses may be circulating among WTD in Texas. Finally, these results supported WNV infection among WTD and highlight their potential role as sentinels for the detection of WNV in Texas and warrant further studies to determine the role WTD play in the maintenance and transmission of WNV.

Complete genomic sequences of Venezuelan equine encephalitis virus subtype IIID isolates from mosquitoes.

Venezuelan equine encephalitis virus (VEEV) is an important pathogen of medical and veterinary importance in the Americas. In this report, we present the complete genome sequences of five VEEV isolates obtained from pools of Culex (Melanoconion) gnomatos (4) or Culex (Melanoconion) pedroi (1) from Iquitos, Peru. Genetic and phylogenetic analyses showed that all five isolates grouped within the VEEV complex sister to VEEV IIIC and are members of subtype IIID. This is the first report of full-length genomic sequences of VEEV IIID.

Theoretical risk of genetic reassortment should not impede development of live, attenuated Rift Valley fever (RVF) vaccines commentary on the draft WHO RVF Target Product Profile.

In November 2019, The World Health Organization (WHO) issued a draft set of Target Product Profiles (TPPs) describing optimal and minimally acceptable targets for vaccines against Rift Valley fever (RVF), a Phlebovirus with a three segmented genome, in both humans and ruminants. The TPPs contained rigid requirements to protect against genomic reassortment of live, attenuated vaccines (LAVs) with wild-type RVF virus (RVFV), which place undue constraints on development and regulatory approval of LAVs. We review the current LAVs in use and in development, and conclude that there is no evidence that reassortment between LAVs and wild-type RVFV has occurred during field use, that such a reassortment event if it occurred would have no untoward consequence, and that the TPPs should be revised to provide a more balanced assessment of the benefits versus the theoretical risks of reassortment.

Circulation of Rift Valley Fever Virus Antibody in Cattle during Inter-Epizootic/Epidemic Periods in Selected Regions of Tanzania.

Tanzania is one of the sub-Saharan countries that have experienced a number of Rift Valley fever (RVF) outbreaks at intervals of 10-20 years since the first isolation of the virus during the early 1930s. Recent studies have reported serological evidence of inter epizootic/epidemic period circulation of RVF virus (RVFV) in livestock and humans. The aim of this study was to conduct a cross-sectional survey in Tanzania during 2015/16 to further explore the possibility that RVFV was circulating among cattle during the Inter epizootic/epidemic period. A total of 443 cattle samples were collected in Manyara, Dodoma, Singida, and Mbeya regions of Tanzania. The samples were tested for RVFV antibodies using a commercial ELISA kit and a plaque reduction neutralization test. Serum samples were also tested for RVFV viral RNA by an reverse transcription polymerase chain reaction (RT-PCR) assay. An overall RVFV seroprevalence rate of 7.7% (34/443) was detected by ELISA among cattle in all four regions. The Mbeya region cattle had the highest seroprevalence of 26.4% (23/87), followed by Dodoma 5.9% (10/171) and lastly Singida 0.9% (1/101). Of 33 ELISA antibody-positive samples, only 0.2% (1/443) had IgM antibody. Of 36 ELISA antibody-positive and doubtful samples, 32 were positive for neutralizing antibody with titers between 10 and > 10,240. None of the samples were positive for RVFV viral RNA by RT-PCR. The detection of RVFV antibodies in cattle suggested that these animals were involved in an enzootic cycle during the interepidemic period and that the high antibody titers may confer protection of cattle against RVFV.

Schlafen 11 Restricts Flavivirus Replication.

Schlafen 11 (Slfn11) is an interferon-stimulated gene that controls the synthesis of proteins by regulating tRNA abundance. Likely through this mechanism, Slfn11 has previously been shown to impair human immunodeficiency virus type 1 (HIV-1) infection and the expression of codon-biased open reading frames. Because replication of positive-sense single-stranded RNA [(+)ssRNA] viruses requires the immediate translation of the incoming viral genome, whereas negative-sense single-stranded RNA [(-)ssRNA] viruses carry at infection an RNA replicase that makes multiple translation-competent copies of the incoming viral genome, we reasoned that (+)ssRNA viruses will be more sensitive to the effect of Slfn11 on protein synthesis than (-)ssRNA viruses. To evaluate this hypothesis, we tested the effects of Slfn11 on the replication of a panel of ssRNA viruses in the human glioblastoma cell line A172, which naturally expresses Slfn11. Depletion of Slfn11 significantly increased the replication of (+)ssRNA viruses from the Flavivirus genus, including West Nile virus (WNV), dengue virus (DENV), and Zika virus (ZIKV), but had no significant effect on the replication of the (-)ssRNA viruses vesicular stomatitis virus (VSV) (Rhabdoviridae family) and Rift Valley fever virus (RVFV) (Phenuiviridae family). Quantification of the ratio of genome-containing viral particles to PFU indicated that Slfn11 impairs WNV infectivity. Intriguingly, Slfn11 prevented WNV-induced downregulation of a subset of tRNAs implicated in the translation of 11.8% of the viral polyprotein. Low-abundance tRNAs might promote optimal protein folding and enhance viral infectivity, as previously reported. In summary, this study demonstrates that Slfn11 restricts flavivirus replication by impairing viral infectivity.IMPORTANCE We provide evidence that the cellular protein Schlafen 11 (Slfn11) impairs replication of flaviviruses, including West Nile virus (WNV), dengue virus (DENV), and Zika virus (ZIKV). However, replication of single-stranded negative RNA viruses was not affected. Specifically, Slfn11 decreases the infectivity of WNV potentially by preventing virus-induced modifications of the host tRNA repertoire that could lead to enhanced viral protein folding. Furthermore, we demonstrate that Slfn11 is not the limiting factor of this novel broad antiviral pathway.