I will be completely honest and start by saying that this week was long and did not go as smoothly as I might have liked! That being said, everything that needed to be completed for the experiment was successfully completed, so the week ended on a positive note.
In recent weeks, our primary goal was rearing the mosquitoes that we would need for our experiment. The eggs that we hatched just a couple weeks ago are now adults. On Monday and Tuesday, those mosquitoes needed to be sorted. The process of sorting is simply separating the female and male mosquitoes. To do this, the mosquitoes are aspirated from their cage and knocked down by chilling them on ice. Once they are knocked down, it is relatively easy to distinguish between male and female mosquitoes. Male mosquitoes have much more plumose or feathery antenna compared to females. Female mosquitoes are then placed in a paper cup in groups of 50. A fine mesh is secured on the top of the cup and the mosquitoes are given sugar water.
Now for the part of the week that did not go as planned… In order to feed the mosquitoes a bloodmeal infected with Zika virus, we need the virus. To do this, the virus is placed in a flask with Vero cells (see the previous post) and allowed to replicate and release from the cells. If this virus is harvested at the opportune time, it can result in a high titer (concentration) of the virus. This high titer is what we were aiming for in the experiment and we anticipated harvesting the virus on Wednesday. However, the virus had not progressed as expected and we had to delay bloodfeeding the mosquitoes by one day. Fortunately, this change was easy enough to adjust for but had me concerned for a day or so.
Before describing the infectious bloodmeal, let me apologize for the poor photo quality of the pictures below. They were on my phone that was sealed in a plastic bag (for safety reasons).
Thursday and Friday were the days we fed our mosquitoes their bloodmeal infected with Zika virus. To do this, the harvested virus was mixed with bovine blood and some ATP (to help with feeding). This mixture is loaded into small feeders that are then attached to a Hemotek system. This feeding system heats the blood so it is similar to the human body, which also improves feeding. In the pictures below, you can see the Hemotek feeders mounted on the individual cups of mosquitoes that were sorted on Monday and Tuesday. While it may be hard to make out, the 3rd picture shows a lot of very happy and bloodfed females!
When the mosquitoes have finished taking their bloodmeal, they have to be sorted (again). This time, we are separating the females that fed from those that didn’t. If the female doesn’t take a bloodmeal, than she can’t be infected with the virus. Therefore, females that didn’t feed were discarded and those that fed on the infectious bloodmeal were sorted into new cages.
The process of bloodfeeding is a pretty involved one, as you might imagine. Because we are working with disease-causing agents that can infect humans, there are a number of precautions that must be taken. The protocols in place ensure the safety of those working in the laboratory as well. Above, you can see one of the people working on this project in a full-body suit, wearing 2 pairs of gloves, and working inside of a glovebox (a sealed area that you can insert your hands in).