奶奶

虽然目前难以衡量流行ulation age-structure of mosquitoes, researchers are developing technologies to understand how time governs the way we think of virus-vector interactions.

Time waits for no virus.

A female mosquito takes a bloodmeal with virus in it. If the virus infects the midgut, travels through the mosquito body, and is then able to infect the salivary glands, the mosquito can inject that virus to a susceptible host the next time it bites, becoming a virus vector. Sounds simple enough (narrator: it is not!).

一种常见的方式矢量 - 病毒配对(本文:“配对”)被认为是有效的(请阅读:善于保持传输的运转)是通过矢量能力的组合,外部孵化期(EIP)和诸如矢量的摘要指标的结合容量(VC)。我们最初着手确定年龄如何影响向量能力和EIP,以及如何更好地将它们插入VC方程,因为每个人都喜欢数学。

向量能力(将传播的暴露蚊子的百分比):Vector competence is a spectrum. Let’s say a pairing has “high” vector competence: 50% of exposed mosquitoes will go on to transmit the virus. On the other hypothetical hand, let’s say a pairing has “low” vector competence: only 10% will transmit. We have, as a field, attributed levels of fitness to higher percentages of vector competence. Bigger is better, right?

EIP(所有这种摩斯高质病毒旅行所需的时间):EIP不是一个数字,而是取决于许多因素的分布,包括病毒和/或载体的固有因素​​,以及诸如温度之类的外部因素(此处未解决)。

我们更喜欢考虑EIP和向量能力的相互作用,而不是分别考虑,因为它解释了蚊子内感染的动态。例如,EIP50是50%的蚊子变得感染力所需的时间。同样,您可以定义EIP10or EIP42if you so desire for the time it takes for 10% and 42% of mosquitoes to transmit, respectively.

矢量能力: Everyone loves math, right? VC is a way of taking vector competence, EIP, and a myriad of other mosquito traits and putting it into a mathematical framework that spits out a number. This value can be used to compare pairings or just determine how well a particular pairing might do under a set of circumstances (like environmental variables). The components of vectorial capacity are:

  1. 咬率(蚊子多久咬人咬人,通常由字母A表示) - 似乎是2because it represents the bite where the mosquito gets infected and the one where she transmits.
  2. Density – how many mosquitoes are there for every human in the population
  3. Mosquito mortality – dead mosquitoes don’t transmit
  4. 向量能力和EIP

随着年龄的增长,我背诵了“年龄只是一个数字”的咒语,以证明我对真正老套的动物双关和幼稚的恶作剧的热爱。但是俗话不是错误的 - 年龄是一个数字,因此,当它影响其他数字时,应考虑到它。例如,蚊子的年龄和死亡率是联系的,因为……好吧,这就是时间的工作方式。

在VC中,将蚊子死亡率计算为通过EIP生活的概率而无需考虑蚊子首次感染的年龄。这可能是有问题的,因为它不考虑与年龄/死亡率相对于其他参数的滑动量表。

我们发现了一些有趣的东西:在我们的配对中,在年轻的蚊子和旧蚊子中,能够传输的EIP和比例几乎相同。很酷:负面结果也是结果!

但是,即使存在所有这些事情,也不会在不咬合的情况下进行传播。因此,思维转向了其他实验,我们测试了年龄对咬人行为的影响Ae. aegypti。We decouple that a2term and separated the bite rate into its two components: the bite where she acquires the virus and the bite where she transmits the virus.

What we actually measured was an overall willingness to bite rather than strictly the rate of biting. Turns out, mosquitoes that were young and spry were more likely to probe and/or feed than their older counterparts.

Observed and predicted probabilities of daily biting. The observed daily biting frequencies (dots) from the laboratory experiments and the fitted daily predictions (green curve) (FromMayton,Tramonte,Wear&Christofferson,,,,2020)

With all of these experimental results, we re-tooled the VC equation to account for mosquito age by looking at traits at the time of the first bite (virus in) and the difference in traits at the second bite (virus out). We then calculated VC for mosquitoes that take infected bloodmeals at age 2 days versus older ladies who don’t get infected until 14 days old.

What we found was that there was a certain window of opportunity for the mosquito to successfully transmit. Outside of that window, a mosquito that got infected would not likely contribute to the transmission cycle because she may die before the EIP or she might not bite again.

Time turned out to be very important. Aside from defining this window of opportunity, it similarly defined a window for the virus. Viruses that get out of the mosquito faster but with lower vector competence have an advantage (up to a point) over viruses that are slower, but maybe have moderately higher vector competence.

显然,如果病毒快速并且具有较高的媒介能力,它将获胜。但是,除此之外,这使我们的传播健身的想法变成了一些潮湿。矢量能力值<20%通常被认为是相当差的,但是给出了足够短的EIP10,,,,in the context of age, we show they out-do vector competence of 45% and longer EIP. Time waits for no virus.

虽然目前很难衡量蚊子的人口年龄结构(可悲的是,您无法剖析它们并计算戒指),但研究人员正在开发技术来做到这一点。当他们成功(玻璃满一半!)时,这种对时间如何控制我们对病毒量相互作用的方式的理解是:传播将意味着一些非常酷的研究尚未到来。

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