RESUMO
Vector control has been an essential strategy in Brazil to manage vector-borne diseases, and the use of insecticides plays an important role in this effort. Pyriproxyfen (PPF) has become a common insect growth regulator used to control juvenile stages of mosquitoes by disturbing their growth and development. This study assesses the susceptibility and resistance status of Brazilian Ae. aegypti populations that previously showed low resistance levels to PPF. Eggs of Ae. aegypti were collected from six cities located in the northeast states of Ceará (Quixadá, Icó, and Juazeiro do Norte), and Bahia (Itabuna, Brumado, and Serrinha). We used the Ae. aegypti Rockefeller strain as an experimental control and a strain known to be susceptible to insecticides. Inhibition of emergence rates by 50% of Ae. aegypti populations varied from 0.0098-0.046 µg/L. Mosquitoes from Icó, Serrinha, and Brumado showed low resistance levels [resistance ratio (RR50) = 2.33, 4.52, and 4.83, respectively], whereas moderate levels of resistance were detected in populations from Juazeiro do Norte (RR50=5.83) and Itabuna (RR50=7.88). Aedes aegypti collected from the Quixadá population showed a high resistance level to pyriproxyfen (RR50=11). The evolution of resistance in Brazilian Ae. aegypti populations to PPF can compromise vector control efforts. Continuous monitoring of insecticide resistance in Ae. aegypti is essential for making timely management decisions for effective vector control and management.
Assuntos
Aedes , Inseticidas , Piretrinas , Animais , Inseticidas/farmacologia , Resistência a Inseticidas , Brasil/epidemiologia , Hormônios Juvenis/farmacologia , Mosquitos Vetores , Piretrinas/farmacologiaRESUMO
Zika virus (ZIKV) infection has caused devastating consequences in Brazil as infections were associated with neurological complications in neonates. Aedes aegypti is the primary vector of ZIKV, and the evolution of insecticide resistance (IR) in this species can compromise control efforts. Although relative levels of phenotypic IR in mosquitoes can change considerably over time, its influence on vector competence for arboviruses is unclear. Pyriproxyfen (PPF)-resistant populations of Ae. aegypti were collected from five municipalities located in Northeast of Brazil, which demonstrated different resistance levels; low (Serrinha, Brumado), moderate (Juazeiro do Norte, Itabuna), and high (Quixadá). Experimental per os infection using ZIKV were performed with individuals from these populations and with an insecticide susceptible strain (Rockefeller) to determine their relative vector competence for ZIKV. Although all populations were competent to transmit ZIKV, mosquitoes derived from populations with moderate to high levels of IR exhibited similar or lower susceptibility to ZIKV infection than those from populations with low IR or the susceptible strain. These observations suggest an association between IR and arbovirus infection, which may be attributable to genetic hitchhiking. The use of PPF to control Brazilian Ae. aegypti may be associated with an indirect benefit of reduced susceptibility to infection, but no changes in disseminated infection and transmission of ZIKV among PPF-resistant phenotypes.
Assuntos
Aedes , Inseticidas , Infecção por Zika virus , Zika virus , Animais , Zika virus/genética , Brasil , Mosquitos Vetores , Inseticidas/farmacologia , SalivaRESUMO
Recurrence of local transmission of Zika virus in Puerto Rico is a major public health risk to the United States, where mosquitoes Aedes aegypti (Linnaeus) and Aedes mediovittatus (Coquillett) are abundant. To determine the extent to which Ae. mediovittatus are capable of transmitting Zika virus and the influence of viremia, we evaluated infection and transmission in Ae. mediovittatus and Ae. aegypti from Puerto Rico using serial dilutions of infectious blood. Higher doses of infectious blood resulted in greater infection rates in both mosquitoes. Aedes aegypti females were up to twice as susceptible to infection than Ae. mediovittatus, indicating a more effective midgut infection barrier in the latter mosquito species. Aedes aegypti exhibited higher disseminated infection (40-95%) than Ae. mediovittatus (<5%), suggesting a substantial midgut escape barrier in Ae. mediovittatus. For Ae. aegypti, transmission rates were low over a range of doses of Zika virus ingested, suggesting substantial salivary gland barriers.
Assuntos
Aedes/virologia , Mosquitos Vetores/virologia , Infecção por Zika virus/transmissão , Zika virus/fisiologia , Animais , Humanos , Porto Rico , Especificidade da EspécieRESUMO
Chikungunya virus (CHIKV) is a vector-borne alphavirus transmitted by the bites of mosquitoes, specifically infected, female mosquitoes of the invasive Aedes species. In nature, CHIKV can be maintained by vertical transmission, a phenomenon that relates to the transfer of CHIKV from the infected parent to their offspring within the ovary or during oviposition. In the present study, we conducted laboratory experiments to determine vertical transmission with Ae. albopictus populations from Brazil and Florida. Parental Ae. albopictus females were orally infected with the emergent Asian genotype of CHIKV in the first gonotrophic cycle (infectious blood meal) and tested for vertical transmission following the second (non-infectious blood meal) gonotrophic cycle. CHIKV infection and CHIKV viral titer in parental females were significantly related to population origin, with Brazilian Ae. albopictus showing higher viral dissemination and viral titer than the Florida population. Experimental vertical transmission of CHIKV was documented in one pool of female and four pools of male Ae. albopictus from Brazil (minimum infection rate, MIR, of 0.76% and 2.86%, respectively, for females and males). For the Florida population of Ae. albopictus, only one pool of males was positive for CHIKV infection, with an MIR of 1.06%. Our results demonstrate that Ae. albopictus populations from Brazil and Florida show heterogeneous CHIKV dissemination and vertical transmission, which may contribute to the epidemiology of CHIKV and may be particularly relevant to virus survival during inter-epidemic periods.
Assuntos
Aedes/virologia , Febre de Chikungunya/transmissão , Vírus Chikungunya/fisiologia , Mosquitos Vetores/virologia , Aedes/classificação , Animais , Brasil/epidemiologia , Febre de Chikungunya/epidemiologia , Vírus Chikungunya/genética , Feminino , Florida/epidemiologia , Genótipo , Especificidade de Hospedeiro , Transmissão Vertical de Doenças Infecciosas , Masculino , Mosquitos Vetores/classificaçãoRESUMO
Chikungunya virus is a vector-borne alphavirus transmitted by the bites of infected female Ae. aegypti and Ae. albopictus. In Brazil between 2014 and 2016 almost 320 thousand autochthonous human cases were reported and in Florida numerous imported CHIKV viremic cases (> 3,800) demonstrate the potential high risk to establishment of local transmission. In the present study, we carried out a series of experiments to determine the viral dissemination and transmission rates of different Brazilian and Florida populations of Ae. aegypti and Ae. albopictus at 2, 5, and 13 days post-infection for the emergent Asian genotype of CHIKV. Our results show that all tested populations of Ae. aegypti and Ae. albopictus have a high proportion (> 0.80) of individuals with disseminated infection as early as 2 days-post exposure. We found no significant treatment effects of mosquito population origin effects on viral dissemination rates. Transmission rates had a heterogeneous pattern, with US Ae. aegypti and Brazilian Ae. albopictus having the highest proportion of individuals with successful infection (respectively 0.50 and 0.82 as early as 2 days-post infection). Model results found significant effects of population origin, population origin x species, population origin x days post-infection and population origin x species x days post infection.
Assuntos
Aedes/virologia , Febre de Chikungunya/transmissão , Vírus Chikungunya/fisiologia , Mosquitos Vetores/virologia , Aedes/classificação , Animais , Brasil/epidemiologia , Febre de Chikungunya/epidemiologia , Febre de Chikungunya/virologia , Vírus Chikungunya/genética , Feminino , Florida/epidemiologia , Genótipo , Humanos , Filogeografia , Saliva/virologiaRESUMO
Commercially available assays utilizing antigen or nucleic acid detection chemistries provide options for mosquito control districts to screen their mosquito populations for arboviruses and make timely operational decisions regarding vector control. These assays may be utilized even more advantageously when combined with honey-soaked nucleic acid preservation substrate ('honey card') testing by reducing or replacing the time- and labor-intensive efforts of identifying and processing mosquito pools. We tested artificially inoculated honey cards and cards fed upon individually by West Nile virus (WNV) and Zika virus (ZIKV)-infected mosquitoes with three assays to compare detection rates and the limit of detection for each platform with respect to virus detection of a single infected mosquito and quantify the time interval of virus preservation on the cards. Assays evaluated included CDC protocols for real-time reverse transcriptase polymerase chain reaction (RT-PCR) for WNV and ZIKV, Pro-Lab Diagnostics ProAmpRT WNV loop-mediated amplification (LAMP) and ZIKV LAMP assays, and the Rapid Analyte Measurement Platform (RAMP) WNV assay. Real-time RT-PCR was the most sensitive assay and the most robust to viral RNA degradation over time. To maximize the detection of virus, honey cards should be left in the traps ≤1 d if using LAMP assays and ≤3 d if using real-time RT-PCR to detect viruses from field samples. The WNV RAMP assay, although effective for pool screening, lacks sensitivity required for honey card surveillance. Future studies may determine the minimum number of infectious mosquitoes required to feed on a honey card that would be reliably detected by the LAMP or RAMP assays.
Assuntos
Culex/virologia , Controle de Mosquitos/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Reação em Cadeia da Polimerase/métodos , Vírus do Nilo Ocidental/isolamento & purificação , Zika virus/isolamento & purificação , Animais , Mel/análise , Mel/virologia , Mosquitos Vetores/virologiaRESUMO
BACKGROUND: Dengue viruses (DENV) are considered one of the most important emerging pathogens and dengue disease is a global health threat. The geographic expansion of dengue viruses has led to co-circulation of all four dengue serotypes making it imperative that new DENV control strategies be devised. OBJECTIVES: Here we characterize dengue serotype-specific innate immune responses in Aedes aegypti and Aedes albopictus using DENV from Puerto Rico (PR). METHODS: Ae. aegypti and Ae. albopictus were infected with dengue serotype 1 and 2 isolated from Puerto Rico. DENV infected mosquito samples were collected and temporal change in expression of selected innate immune response pathway genes analyzed by quantitative real time PCR. FINDINGS: The Toll pathway is involved in anti-dengue response in Ae. aegypti, and Ae. albopictus. Infections with PR DENV- 1 elicited a stronger response from genes of the Toll immune pathway than PR DENV-2 in Ae. aegypti but in infected Ae. albopictus expression of Toll pathway genes tended to be similar between the serotypes. Two genes (a ribosomal S5 protein gene and a nimrod-like gene) from Ae. albopictus were expressed in response to DENV. MAIN CONCLUSIONS: These studies revealed a role for antiviral genes in DENV serotype-specific interactions with DENV vectors, demonstrated that infections with DENV-2 can modulate the Toll immune response pathway in Ae. aegypti and elucidated candidate molecules that might be used to interfere with serotype specific vector-virus interactions.
Assuntos
Aedes/virologia , Vírus da Dengue/genética , Insetos Vetores/virologia , Aedes/classificação , Animais , Vírus da Dengue/imunologia , Vírus da Dengue/isolamento & purificação , Insetos Vetores/classificação , Reação em Cadeia da Polimerase em Tempo RealRESUMO
BACKGROUND Dengue viruses (DENV) are considered one of the most important emerging pathogens and dengue disease is a global health threat. The geographic expansion of dengue viruses has led to co-circulation of all four dengue serotypes making it imperative that new DENV control strategies be devised. OBJECTIVES Here we characterize dengue serotype-specific innate immune responses in Aedes aegypti and Aedes albopictus using DENV from Puerto Rico (PR). METHODS Ae. aegypti and Ae. albopictus were infected with dengue serotype 1 and 2 isolated from Puerto Rico. DENV infected mosquito samples were collected and temporal change in expression of selected innate immune response pathway genes analyzed by quantitative real time PCR. FINDINGS The Toll pathway is involved in anti-dengue response in Ae. aegypti, and Ae. albopictus. Infections with PR DENV- 1 elicited a stronger response from genes of the Toll immune pathway than PR DENV-2 in Ae. aegypti but in infected Ae. albopictus expression of Toll pathway genes tended to be similar between the serotypes. Two genes (a ribosomal S5 protein gene and a nimrod-like gene) from Ae. albopictus were expressed in response to DENV. MAIN CONCLUSIONS These studies revealed a role for antiviral genes in DENV serotype-specific interactions with DENV vectors, demonstrated that infections with DENV-2 can modulate the Toll immune response pathway in Ae. aegypti and elucidated candidate molecules that might be used to interfere with serotype specific vector-virus interactions.
Assuntos
Animais , Aedes/classificação , Aedes/virologia , Vírus da Dengue/isolamento & purificação , Vírus da Dengue/genética , Vírus da Dengue/imunologia , Insetos Vetores/classificação , Insetos Vetores/virologia , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Between 2014 and 2016 more than 3,800 imported human cases of chikungunya fever in Florida highlight the high risk for local transmission. To examine the potential for sustained local transmission of chikungunya virus (CHIKV) in Florida we tested whether local populations of Aedes aegypti and Aedes albopictus show differences in susceptibility to infection and transmission to two emergent lineages of CHIKV, Indian Ocean (IOC) and Asian genotypes (AC) in laboratory experiments. All examined populations of Ae. aegypti and Ae. albopictus mosquitoes displayed susceptibility to infection, rapid viral dissemination into the hemocoel, and transmission for both emergent lineages of CHIKV. Aedes albopictus had higher disseminated infection and transmission of IOC sooner after ingesting CHIKV infected blood than Ae. aegypti. Aedes aegypti had higher disseminated infection and transmission later during infection with AC than Ae. albopictus. Viral dissemination and transmission of AC declined during the extrinsic incubation period, suggesting that transmission risk declines with length of infection. Interestingly, the reduction in transmission of AC was less in Ae. aegypti than Ae. albopictus, suggesting that older Ae. aegypti females are relatively more competent vectors than similar aged Ae. albopictus females. Aedes aegypti originating from the Dominican Republic had viral dissemination and transmission rates for IOC and AC strains that were lower than for Florida vectors. We identified small-scale geographic variation in vector competence among Ae. aegypti and Ae. albopictus that may contribute to regional differences in risk of CHIKV transmission in Florida.
Assuntos
Aedes/crescimento & desenvolvimento , Aedes/virologia , Vírus Chikungunya/isolamento & purificação , Mosquitos Vetores/crescimento & desenvolvimento , Mosquitos Vetores/virologia , Tropismo Viral , Animais , Febre de Chikungunya/transmissão , Vírus Chikungunya/classificação , Vírus Chikungunya/genética , Estudos de Coortes , Transmissão de Doença Infecciosa , República Dominicana , Feminino , Florida , Medição de RiscoRESUMO
Locally acquired dengue cases in the continental U.S. are rare. However, outbreaks of dengue-1 during 2009, 2010, and 2013 in Florida and dengue-1 and -2 in Texas suggest vulnerability to transmission. Travel and commerce between Puerto Rico and the U.S. mainland is common, which may pose a risk for traveler-imported dengue cases. Mosquitoes were collected in Florida and used to evaluate their susceptibility to dengue viruses (DENV) from Puerto Rico. Aedes aegypti and Ae. albopictus were susceptible to virus infection with DENV-1 and -2. No significant differences were observed in rates of midgut infection or dissemination between Ae. aegypti or Ae. albopictus for DENV-1 (6-14%). Aedes aegypti was significantly more susceptible to midgut infection with DENV-2 than Ae. albopictus (Ae. aegypti, â¼28%; Ae. albopictus, â¼9%). The dissemination rate with dengue-2 virus for Ae. aegypti (23%) was greater than Ae. albopictus (0%), suggesting that Ae. albopictus is not likely to be an important transmitter of the DENV-2 isolate from Puerto Rico. These results are discussed in light of Florida's vulnerability to DENV transmission.