Why some viruses could be transmitted by mosquitos and others like AIDS not?
Many mosquito-borne virus have to be ingested by the mosquito and then pass through the midgut travel to the salivary glands and then infect the salivary glands and complete this development prior to future bloodmeals. HIV is likely not adapted to overcome these different barriers in mosquitoes and other biting flies.
Agree with Dustin, and as far as I know too, the viral titer acquired by the mosquito during feeding is not enough to cause the disease.
Dustin is correct, you have to distinguish between mechanical and biological vectors. Mosquitoes are biological vectors, which means that the pathogen (the virus) must replicate in the mosquito tissue before it can be transmitted. Indeed, arboviruses do infect mosquitoes and replicate in the midgut and in the salivary glands, the mosquito is just able to tollerate viral replication, there is no fitness reduction. This is because ZIKV and other arboviruses are thought to be derived from Insect specific viruses, which can only infect mosquitoes. These viruses have evolved to also infect vertebrates, to have more hosts and became arboviruses: Zika, Dengue, West nile... HIV, and the majority of other viruses, have a completely different origin, they were born as vertebrate virus, they infect mammals. So they do not "recognise" mosquito cells and cannot replicate in mosquitoes.
Article Insect-Specific Virus Discovery: Significance for the Arbovi...
La duda persiste para mi , hay que comparar que los arbovirus son más pequeños que el de HIV y pueden ser succionados por el mosquito, el virus de VIH tiene mayor tamaño y el Articulo no refiere estudio de células de mosquitos con el HIV.
Gracias Humberto por Compartir El Articulo: Descubriendo Virus Insecto Especificos
The doubt persists for me, we must compare that the arboviruses are smaller than the HIV virus and can be sucked by the mosquito, the HIV virus is larger and the article does not refer to the study of mosquito cells with HIV.
Thank you Umberto for share this Article: Insect Specific Virus Discovery.......
Dear Marcelo,
This was assessed by researchers at South Africa's NIV (now the NICD) in 1986 for one of our most common domestic mosquitoes and 2 bed bug species, partially due to South Africa's unenviable HIV status: Jupp PG & Lyons S. 1987. Experimental assessment of bedbugs (Cimex lectularius and Cimex hemipterus) and mosquitoes (Aedes aegypti formosus) as vectors of human immunodeficiency virus. AIDS 1(3, Sep):171-4. The researchers found survival of HIV in the bed bugs for a limited number of hours post-bite but none in the mosquito, implying absence of viral replication. They also assessed the possibility of mechanical transmission as a result of interrupted feeding, with virus particles adhering to the mouth-parts - this also does not appear to occur readily, if at all.
Several articles have been written giving rational explanations for why HIV is not vector-borne, e.g., https://www.scientificamerican.com/article/if-a-used-needle-can-tran/
Gracias Alan Kemp. ThansK you Alan Kemp Traducción al español del Articulo de https://www.scientificamerican.com/article/if-a-used-needle-can-tran/ Laurence Corash, Oficial Jefe Medico de Cerus Corporation, Provee la siguiente explicación:
El virus del SIDA (VIH) en las agujas usadas es infeccioso cuando se inyecta en un humano donde el virus puede unirse a las células T y comenzar a replicarse. La célula T humana es una célula huésped muy específica para el VIH. Cuando un mosquito se alimenta de una persona con VIH en su sangre, el VIH entra en el intestino del insecto, que no contiene células T humanas. Por lo tanto, el virus no tiene una célula huésped en la que replicar y se descompone por el sistema digestivo del mosquito. El parásito unicelular que causa la malaria, en contraste, puede sobrevivir y multiplicarse en el intestino del mosquito y madurar en una forma infecciosa. Los esporozoitos resultantes migran a las glándulas salivales del insecto. Debido a que los mosquitos inyectan su saliva cuando muerden, el parásito se pasa al siguiente humano del que se alimenta el insecto. En este caso, la compleja interacción entre el agente infeccioso y el vector (el mosquito) es necesaria para la transmisión. El VIH, sin embargo, se deteriora en el intestino antes de que el mosquito muerde de nuevo y por lo tanto no se transmite a la próxima víctima del insecto. Mi pregunta: ¿Habra alguna sustancia secretada por las células intestinales del mosquito que cure el VIH? Will there be any substance secreted by the intestinal cells of the mosquito that cures HIV?
Hi Jorge,
The size of the virus is not relevant in its transmission through arthropods, mosquitoes can take a large volume of liquids. Consider that Plasmodium is larger than any virus and still it can enter and replicate in mosquitoes.
To answer your question: I'd say no, there are not specific anti-HIV mechanism in mosquitoes (I think). What Laurence Corash said, which is correct, is that basically the virus die both because it is digested in mosquito (which is normal, it also happens if a human ingests non-pathogenic viruses, they are just digested. Viruses are proteins and DNA after all. They need to enter and parasite cells to survive and replicates, in mosquitoes as Corash said there are no T-Cells, so no "home" for the virus.
They cannot get protected from digestive enzymes and cannot replicate, so they get degraded.
La hipótesis está lanzada, la ciencia no es de creencias, sino de demostraciones que se pueden replicar, Una enfermedad que destruye, tanto ligada a la conducta humana como factor de transmisión, implica investigar toda posibilidad de tratamiento, puede que sea alguna sustancia digestiva del mosquito que no afecte al humano pero si letal para el HIV?. Como NO estoy trabajando en un Laboratorio de Investigación de alta complejidad, queda la hipótesis para investigarla quien la pueda hacer. Y de ser cierta. se podría curar IV el VIH. Rojas ahí está la idea para que se lo haga en Chile.
The hypothesis is launched, the science is not of beliefs, but of demonstrations that can be replicated. A disease that destroys, both linked to human behavior as a transmission factor, involves investigating any possibility of treatment, it may be some digestive substance of the Mosquito that does not affect the human but is lethal for HIV ?. Since I am not working in a highly complex Research Laboratory, there is the hypothesis to investigate who can do it. And to be true. Could be an IV treatment for HIV.
There are many approaches that pathogens take to work with vector and host (plant or animal).
1) Mouthparts act as a dirty needle. Old paradigm. At least some of these cases have been studied further and are actually #3 below.
2) Mouthparts act as a syringe. A small quantity of liquid from last meal is retained in the mouthparts and spit back out at the start of a new probing site.
3) Mouthparts have specific biochemical binding sites to retain the pathogen between hosts. (aphid borne viruses)
4) Mouthparts are colonized by the pathogen but pathogen does not pass through gut wall (sharpshooters and Pierce's disease of grape).
5) Pathogen is circulative (passes through gut wall, travels through haemolymph, enters salivary glands, is injected into new host). No replication of pathogen in the vector.
6) Pathogen replicates somewhere in the insect along the pathway described in 5.
If #1 happens, one would expect some level of disease transmission for all arthropods. I suspect that pathogen mortality is high if the pathogen is only surface contamination. I can think of specific cases for all except option #5.
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