Name: vector competence analyses on aedes aegypti mosquitoes using zika virus
Uploaded: 2020-05-31T14:00:00
Description: Watch this Scientific Journal Video about Vector Competence Analyses on Aedes aegypti Mosquitoes using Zika Virus at JoVE.com

We acknowledge the staff of the World Reference Center for Emerging Viruses and Arboviruses (WRCEVA): Dr. Robert Tesh, Hilda Guzman, Dr. Kenneth Plante, Dr. Jessica Plante, Dionna Scharton, and Divya Mirchandani, for their tireless work in curating and providing many of the viral strains used for our and other groups&#8217; vector competence experiments. The presented work was funded by the McLaughlin Fellowship Fund (SRA) and NIH grants AI120942 and AI121452.

All procedures performed in these protocols were performed in full compliance with protocols approved&#160;by the Institutional Biosafety Committee and the Institutional Animal Care and Use Committee of the University of Texas Medical Branch at Galveston.
1. Amplify ZIKV in Vero cells
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	<li>Grow Vero cells (CCL-81 or VeroE6) in Dulbecco&#8217;s modification of Eagle&#8217;s minimal essential medium (DMEM) supplemented with 10% v/v heat-inactivated fetal bovine serum (FBS), and 1% (v/v) p...

<ol>
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K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Colonized+Sabethes+cyaneus,+a+Sylvatic+New+World+Mosquito+Species,+Shows+a+Low+Vector+Competence+for+Zika+Virus+Relative+to+Aedes+aegypti.">Colonized Sabethes cyaneus, a Sylvatic New World Mosquito Species, Shows a Low Vector Competence for Zika Virus Relative to Aedes aegypti.</a> Viruses. 10 (8), 434 (2018).</li><li>Roundy, C. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variation+in+Aedes+aegypti+Mosquito+Competence+for+Zika+Virus+Transmission.">Variation in Aedes aegypti Mosquito Competence for Zika Virus Transmission.</a> Emerging Infectious Diseases. 23 (4), 625-632 (2017).</li><li>Wilson, A. J., Harrup, L. 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The methods described here provide a generalized workflow to conduct vector competence analyses. As a general framework, many of these methodologies are conserved throughout the literature. However, there is substantial room for modifications (reviewed in Azar and Weaver1). Virus (e.g., viral lineage, storage of challenge virus, viral passage history), entomology (e.g., laboratory colonization of mosquito populations, innate immunity, the mosquito microbiome/virome), and experimental variables (e....

Vector competence is defined as the ability at the level of species, population, and even an individual, of a given arthropod such as a mosquito, tick, or phlebotomine sand fly, to acquire and transmit an agent biologically with replication or development in the arthropod1,2. With respect to mosquitoes and arthropod-borne viruses (i.e., arboviruses), the agent is imbibed from a viremic host by a female mosquito. Following ingestion, the virus must productively infect one of a small population of midgut epithelial cells3, overcoming various physiological obstacles such as proteolytic degradation by digestive enzymes, the presence of the microbiota (midgut infection barrier, or MIB), and the secreted peritrophic matrix. Infection of the midgut epithelium must be followed by replication of the virus and eventual escape from the midgut into the mosquito&#8217;s open circulatory system, or hemolymph, which represents the onset of a disseminated infection overcoming the midgut escape barrier (MEB). At this point the virus can establish infections of secondary tissues (e.g., nerves, muscles, and fat bodies) and continue to replicate, although such secondary replication may not be strictly necessary for the virus to infect the acinar cells of the salivary glands (overcoming the salivary gland infection barrier). Egress from the salivary gland acinar cells into their apical cavities and then movement into the salivary duct enables inoculation of the virus into subsequent hosts on biting, and completes the transmission cycle1,2,4,5,6,7.
Given this well-characterized and generally conserved mechanism of spread within a mosquito vector, laboratory vector competence assessments are often methodologically similar, although differences in protocols do exist1,2. Generally, after oral virus exposure, mosquitoes are dissected so that individual tissues such as the midgut, legs, ovaries, or salivary glands can be assayed for viral infection, disseminated infection, disseminated infection/potential transovarial transmission, and disseminated infection/potential transmission competence, respectively8. The mere presence of a virus in the salivary glands, however, is not definitive evidence of transmission capability, given evidence of a salivary gland escape/egress barrier (SGEB) in some vector/virus combinations1,2,4,5,7,9. The standard method to prove transmission competence remains mosquito transmission to a susceptible animal10,11,12. However, given that for many arboviruses this necessitates the use of immunocompromised murine models13,14,15,16, this method is often cost-prohibitive. A commonly used alternative is the collection of the mosquito saliva, which can be analyzed by reverse transcription-polymerase chain reaction (RT-PCR) or an infectious assay to demonstrate the presence of the viral genome or infectious particles, respectively. It is worth noting that such in vitro saliva collection methods may overestimate12 or underestimate17 the amount of virus deposited during in vivo feeding, indicating that such data must be interpreted with caution. Nonetheless, the in vitro method is highly valuable when analyzed from the perspective of the mere presence of virus in the saliva, indicating transmission potential.
Two major approaches exist for determining the role of mosquito vectors in arboviral disease outbreaks. The first method involves field surveillance, in which mosquitoes are collected in the context of active transmission18,19,20,21,22,23,24. However, given that infection rates are typically quite low (e.g., the estimated 0.061% infection rate of mosquitoes in areas of active Zika virus (ZIKV) circulation in the United States21), incrimination of potential vector species can be heavily biased by trapping methodology25,26 and random chance (e.g., sampling one infected individual out of 1,600 uninfected)21. Taking this into account, a given study may not acquire sufficient mosquitoes in both raw numbers or species diversity to accurately sample mosquitoes involved in transmission. In contrast, vector competence analyses are undertaken in a laboratory setting, allowing for strict control of parameters such as oral dose. Although not fully capable of representing the true complexity of mosquito infection and transmission capability in a field setting, these laboratory assessments remain powerful tools in the field of arbovirology.
Based on various vector competence analyses with ZIKV in several mosquito species, populations, and methods27,28,29,30,31,32, as well as a recent review of vector competence assessments1, we describe here several of the protocols associated with a typical vector competence workflow. In these experiments, three Ae. aegypti populations from the Americas (the city of Salvador, Brazil; the Dominican Republic; and the lower Rio Grande Valley, TX, USA) were exposed to a single strain of ZIKV (Mex 1-7, GenBank Accession: KX247632.1) at 4, 5, or 6 log10 focus-forming units (FFU)/mL doses by way of artificial bloodmeals. Subsequently, they were analyzed for evidence of infection, disseminated infection, and transmission competence after various times of extrinsic incubation (2, 4, 7, 10, and 14 days) by means of dissection and a cell culture-based infectious assay. Although the present workflow/protocols are optimized for ZIKV, many elements are directly translatable to other mosquito-borne arboviruses in arthropod containment and biosafety levels 2 and 3 (ACL/BSL2 or ACL/BSL3).

<table>
	<tbody>
		<tr>
			<td>3mL Standard Reservoir</td>
			<td>R37P30</td>
			<td>Hemotek Ltd</td>
			<td>Insectary Equipment</td>
		</tr>
		<tr>
			<td>7/32&#34; Stainless Steel 440 Grade C Balls</td>
			<td>4RJH9</td>
			<td>Grainger</td>
			<td>Grinding Media</td>
		</tr>
		<tr>
			<td>Acetone, Histological Grade, Fisher Chemicals, Poly Bottle, 4L, 4/Case</td>
			<td>A16-P4</td>
			<td>FisherScientific</td>
			<td>Fixative</td>
		</tr>
		<tr>
			<td>Adenosine 5&#39;-triphospate disodium salt hydrat, microbial, BioReagent, suitable for cell culture</td>
			<td>A6419-1G</td>
			<td>MilliporeSigma</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>Anti-Flavivirus Group Antigen Antibody, clone D1-4G2-4-15</td>
			<td>MAB10216</td>
			<td>MilliporeSigma</td>
			<td>Primary Antibody for focus forming assay</td>
		</tr>
		<tr>
			<td>Anti-Mouse IgG (H+L) Antibody, Human Serum Adsorbed and Peroxidase-Labeled, 1.0mL/Bottle</td>
			<td>5450-0011</td>
			<td>KPL/Seracare</td>
			<td>Secondary Antibody for focus forming assay</td>
		</tr>
		<tr>
			<td>Bleach</td>
			<td>NC0427256</td>
			<td>FisherScientific</td>
			<td>Decontamination</td>
		</tr>
		<tr>
			<td>Corning, Cell Culture Treated Flasks, 150cm2, Vented Cap, Case of 50</td>
			<td>10-126-34</td>
			<td>FisherScientific</td>
			<td>Cell culture consumable</td>
		</tr>
		<tr>
			<td>Costar Cell Culture Plates, 24-well, 5/bag, 100/case, Corning</td>
			<td>07-200-740</td>
			<td>FisherScientific</td>
			<td>Cell culture consumable</td>
		</tr>
		<tr>
			<td>Costar Cell Culture Plates, 96-well, 5/bag, 100/case, Corning</td>
			<td>07-200-91</td>
			<td>FisherScientific</td>
			<td>Cell culture consumable</td>
		</tr>
		<tr>
			<td>Crystal Violet</td>
			<td>C0775-100G</td>
			<td>MilliporeSigma</td>
			<td>Stain</td>
		</tr>
		<tr>
			<td>Eppendorf Snap Cap Microcentrifuge Safe-Lock 2mL Tubes, 500/Case</td>
			<td>05-402-7</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>Falcon 15mL Conical Centrigue Tubes</td>
			<td>14-959-70C</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>Falcon 50mL Conical Centrigue Tubes</td>
			<td>14-959-49A</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>Falcon Disposable Polystyrene Serological 10mL Pipets, 200/Case</td>
			<td>13-675-20</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>Falcon Disposable Polystyrene Serological 1mL Pipets, 1000/Case</td>
			<td>13-675-15B</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>Falcon Disposable Polystyrene Serological 25mL Pipets, 200/Case</td>
			<td>13-675-30</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>Falcon Disposable Polystyrene Serological 5mL Pipets, 200/Case</td>
			<td>13-675-22</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>Falcon Standard Tissue Culture Dishes</td>
			<td>08-772B</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum-Premium, 500mL</td>
			<td>S11150</td>
			<td>Atlanta Biologicals</td>
			<td>Cell culture reagent</td>
		</tr>
		<tr>
			<td>Fisherbrand Economy Plain Glass Microscope Slides</td>
			<td>12-550-A3</td>
			<td>FisherScientific</td>
			<td>Immobilization of Mosquitos</td>
		</tr>
		<tr>
			<td>FU1 Feeder</td>
			<td>FU1-0</td>
			<td>Hemotek Ltd</td>
			<td>Insectary Equipment; feeding units</td>
		</tr>
		<tr>
			<td>Gibco DPBS with Calcium and Magnesium, 10 x 500mL Bottles</td>
			<td>140-040-182</td>
			<td>FisherScientific</td>
			<td>Cell culture reagent</td>
		</tr>
		<tr>
			<td>Gibco Fungizone, Amphotericin B, 250&#956;g/mL, 50mL/Bottle</td>
			<td>15-290-026</td>
			<td>Fisher Scientific</td>
			<td>Cell culture reagent</td>
		</tr>
		<tr>
			<td>Gibco Penicillin-Streptomycin (10,000 U/mL), 100mL/Bottle, 20 Bottles/Case</td>
			<td>15-140-163</td>
			<td>FisherScientific</td>
			<td>Cell culture reagent</td>
		</tr>
		<tr>
			<td>Gibco, Tryptsin-EDTA (.25%), Phenol red, 20 x 100mL Bottles</td>
			<td>25-200-114</td>
			<td>FisherScientific</td>
			<td>Cell culture reagent</td>
		</tr>
		<tr>
			<td>Gibcom DMEM, High Glucose, 10 x 500mL Bottles</td>
			<td>11-965-118</td>
			<td>FisherScientific</td>
			<td>Cell culture reagent</td>
		</tr>
		<tr>
			<td>Human Blood, Unspecified Gender, Na-Citrate, 1 Unit</td>
			<td>7203706</td>
			<td>Lampire</td>
			<td>Bloodmeal preparation</td>
		</tr>
		<tr>
			<td>InsectaVac Aspirator</td>
			<td>2809B</td>
			<td>Bioquip</td>
			<td>Insectary Equipment</td>
		</tr>
		<tr>
			<td>Methanol, Certified ACS, Fisher Chemicals, Amber Glass Bottle, 4L, 4/Case</td>
			<td>A412-4</td>
			<td>FisherScientific</td>
			<td>Fixative</td>
		</tr>
		<tr>
			<td>Methyl cellulose, viscosity: 3,500-5,600 cP, 2 % in water(20 &#176;C), 250g/Bottle</td>
			<td>M0512-250G</td>
			<td>MilliporeSigma</td>
			<td>Cell culture reagent</td>
		</tr>
		<tr>
			<td>Micro-chem Plus Disinfectant Detergent</td>
			<td>C849T34</td>
			<td>Thomas Scientific</td>
			<td>Decontamination; working dilution of dual quaternary ammonium</td>
		</tr>
		<tr>
			<td>Mineral Oil, BioReagent, for molecular biology</td>
			<td>M5904-5X5ML</td>
			<td>MilliporeSigma</td>
			<td>Immobilization of Mosquitos</td>
		</tr>
		<tr>
			<td>O-rings</td>
			<td>OR37-25</td>
			<td>Hemotek Ltd</td>
			<td>Insectary Equipment</td>
		</tr>
		<tr>
			<td>Plastic Plugs</td>
			<td>PP5-250</td>
			<td>Hemotek Ltd</td>
			<td>Insectary Equipment</td>
		</tr>
		<tr>
			<td>PS6 Power Unit (110-120V)</td>
			<td>PS6120</td>
			<td>Hemotek Ltd</td>
			<td>Insectary Equipment; power source</td>
		</tr>
		<tr>
			<td>Rubis Forceps, Offset blades, superfine points</td>
			<td>4525</td>
			<td>Bioquip</td>
			<td>Insectary Equipment</td>
		</tr>
		<tr>
			<td>Sarstedt Inc, 2mL Screw Cap Microtube, Conical Bottom, O-ring Cap, Sterile, 1000/Case</td>
			<td>50-809-242</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>Sucrose, BioUltra, for molecular biology</td>
			<td>84097-250G</td>
			<td>MilliporeSigma</td>
			<td>Reagent</td>
		</tr>
		<tr>
			<td>ThermoScientific, ART Barrier Low Retention 1000&#956;L Pipette Tips, 100 tips/Rack, 8 Racks/Pack, 4 Packs/Case</td>
			<td>21-402-487</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>ThermoScientific, ART Barrier Low Retention 200&#956;L Pipette Tips, 96 tips/Rack, 10 Racks/Pack, 5 Packs/Case</td>
			<td>21-402-486</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>ThermoScientific, ART Barrier Low Retention 20&#956;L Pipette Tips, 96 tips/Rack, 10 Racks/Pack, 5 Packs/Case</td>
			<td>21-402-484</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>ThermoScientific, ART Barrier Low Retention, Extended Reach 10&#956;L Pipette Tips, 96 tips/Rack, 10 Racks/Pack, 5 Packs/Case</td>
			<td>21-402-482</td>
			<td>FisherScientific</td>
			<td>Plastic consumable</td>
		</tr>
		<tr>
			<td>TissueLyser II</td>
			<td>85300</td>
			<td>QIAGEN</td>
			<td>Homogenization</td>
		</tr>
		<tr>
			<td>TrueBlue Peroxidase Substrate Kit, 200mL</td>
			<td>5510-0030</td>
			<td>Seracare</td>
			<td>Developing solution for focus forming assay</td>
		</tr>
		<tr>
			<td>Vero</td>
			<td>CCL-81</td>
			<td>American Type Culture Collection</td>
			<td>Mammalian cell line to amplify virus and conduct infectious assay</td>
		</tr>
		<tr>
			<td>Vero C1008 [Vero 76, clone E6, Vero E6]</td>
			<td>CRL-1586</td>
			<td>American Type Culture Collection</td>
			<td>Mammalian cell line to amplify virus and conduct infectious assay</td>
		</tr>
	</tbody>
</table>

vector competence analyses on aedes aegypti mosquitoes using zika virus

The procedures presented describe a generalized methodology to infect Aedes aegypti mosquitoes with Zika virus under laboratory conditions to determine the rate of infection, disseminated infection, and potential transmission of the virus in the mosquito population in question. These procedures are widely utilized with various modifications in vector competence evaluations globally. They are important in determining the potential role that a given mosquito (i.e., species, population, individual) may play in the transmission of a given agent.

Three populations of Ae. aegypti from the Americas (Salvador, Brazil; the Dominican Republic; and the Rio Grande Valley, TX, USA) were exposed to an outbreak strain of ZIKV from the Americas (ZIKV Mex 1-7, Chiapas State, Mexico, 2015) over a range of bloodmeal titers (4, 5, and 6 log10 FFU/mL) presented in a washed human erythrocyte-based artificial bloodmeal. At days 2, 4, 7, 10, and 14 postinfection, subsets of mosquitoes were processed to determine infection, dissemination, and potential transmissi...

Watch this Scientific Journal Video about Vector Competence Analyses on Aedes aegypti Mosquitoes using Zika Virus at JoVE.com

Vector Competence Analyses on Aedes aegypti Mosquitoes using Zika Virus

The presented protocol can determine the vector competence of Aedes aegypti mosquito populations for a given virus, such as Zika, in a containment setting.

Vector Competence Analyses on Aedes aegypti Mosquitoes using Zika Virus

The procedures presented describe a generalized methodology to infect Aedes aegypti mosquitoes with Zika virus under laboratory conditions to determine ...

Research

JoVE Journal

Immunology and Infection

A Calcium Bioluminescence Assay for Functional Analysis of Mosquito (Aedes aegypti) and Tick (Rhipicephalus microplus) G Protein-coupled Receptors

A Calcium Bioluminescence Assay for Functional Analysis of Mosquito Aedes aegypti and Tick Rhipicephalus microplus G Protein-coupled Receptors

Arthropod hormone receptors are potential targets for novel pesticides as they regulate many essential physiological and behavioral processes.  The ...

A Protocol for Collecting and Staining Hemocytes from the Yellow Fever Mosquito Aedes aegypti

A Protocol for Collecting and Staining Hemocytes from the Yellow Fever Mosquito Aedes aegypti

 Mosquitoes are vectors for a number  of disease-causing pathogens such as the yellow fever virus, malaria parasites  and filarial worms. Laboratories are ...

Detection of Infectious Virus from Field-collected Mosquitoes by Vero Cell Culture Assay

Mosquitoes transmit a number of distinct viruses including important human pathogens such as West Nile virus, dengue virus, and chickungunya virus. Many ...

Hybridization in situ of Salivary Glands, Ovaries, and Embryos of Vector Mosquitoes

Hybridization in situ of Salivary Glands, Ovaries, and Embryos of Vector Mosquitoes

Mosquitoes are vectors for a diverse set of pathogens including arboviruses, protozoan parasites and nematodes.  Investigation of transcripts and gene ...

Zika Virus Infectious Cell Culture System and the In Vitro Prophylactic Effect of Interferons

Zika Virus Infectious Cell Culture System and the In Vitro Prophylactic Effect of Interferons

Zika Virus (ZIKV) is an emerging pathogen that is linked to fetal developmental abnormalities such as microcephaly, eye defects, and impaired growth. ZIKV ...

Rescue and Characterization of Recombinant Virus from a New World Zika Virus Infectious Clone

Infectious cDNA clones allow for genetic manipulation of a virus, thus facilitating work on vaccines, pathogenesis, replication, transmission and viral ...

Zika Virus Specific Diagnostic Epitope Discovery

High-density peptide microarrays allow screening of more than six thousand peptides on a single standard microscopy slide. This method can be applied for ...

A Simple Flow Cytometry Based Assay to Determine In Vitro Antibody Dependent Enhancement of Dengue Virus Using Zika Virus Convalescent Serum

A Simple Flow Cytometry Based Assay to Determine In Vitro Antibody Dependent Enhancement of Dengue Virus Using Zika Virus Convalescent Serum

Antibody dependent enhancement of infection has been shown to play a major role in Dengue viral pathogenesis. Traditional assays that measure the capacity ...

Evaluation of Zika Virus-specific T-cell Responses in Immunoprivileged Organs of Infected Ifnar1-/- Mice

Evaluation of Zika Virus-specific T-cell Responses in Immunoprivileged Organs of Infected Ifnar1-/- Mice

The Zika virus (ZIKV) can induce inflammation in immunoprivileged organs (e.g., the brain and testis), leading to the Guillain-Barr&#233; syndrome and ...

Rescue of Recombinant Zika Virus from a Bacterial Artificial Chromosome cDNA Clone

The association of Zika virus (ZIKV) infection with neurological complications during the recent worldwide outbreak and the lack of approved vaccines ...