Endosymbiotic Wolbachia bacteria are potent modulators of pathogen infection and transmission in multiple naturally and artificially infected insect species, including important vectors of human pathogens. Anopheles mosquitoes are naturally uninfected with Wolbachia, and stable artificial infections have not yet succeeded in this genus. Recent techniques have enabled establishment of somatic Wolbachia infections in Anopheles. Here, we characterize somatic infections of two diverse Wolbachia strains (wMelPop and wAlbB) in Anopheles gambiae, the major vector of human malaria. After infection, wMelPop disseminates widely in the mosquito, infecting the fat body, head, sensory organs and other tissues but is notably absent from the midgut and ovaries. Wolbachia initially induces the mosquito immune system, coincident with initial clearing of the infection, but then suppresses expression of immune genes, coincident with Wolbachia replication in the mosquito. Both wMelPop and wAlbB significantly inhibit Plasmodium falciparum oocyst levels in the mosquito midgut. Although not virulent in non-bloodfed mosquitoes, wMelPop exhibits a novel phenotype and is extremely virulent for approximately 12–24 hours post-bloodmeal, after which surviving mosquitoes exhibit similar mortality trajectories to control mosquitoes. The data suggest that if stable transinfections act in a similar manner to somatic infections, Wolbachia could potentially be used as part of a strategy to control the Anopheles mosquitoes that transmit malaria. Infection with Wolbachia bacteria has been shown to reduce pathogen levels in multiple mosquito species. Anopheles mosquitoes (the obligate vectors of human malaria) are naturally uninfected with Wolbachia, and stable artificial infections have not yet succeeded in this genus; however somatic infections can be established that can be used to assess the effect of Wolbachia infection in Anopheles. Here, we show that infection with two different Wolbachia strains (wMelPop and wAlbB) can significantly reduce levels of the human malaria parasite Plasmodium falciparum in Anopheles gambiae. After infection, Wolbachia disseminate throughout the mosquito but are notably absent from the gut and ovaries. The mosquito immune system is first induced in response to Wolbachia infection, but is then suppressed as the infection progresses. The Wolbachia strain wMelPop is highly virulent to Anopheles only after blood feeding. If stable infections can be established in Anopheles, and they act in a similar manner to somatic infections, Wolbachia could potentially be used as part of a strategy to control malaria.

SARS-CoV-2 emerged from animals and is now easily transmitted between people. Sporadic detection of natural cases in animals alongside successful experimental infections of pets, such as cats, ferrets and dogs, raises questions about the susceptibility of animals under natural conditions of pet ownership. Here, we report a large-scale study to assess SARS-CoV-2 infection in 919 companion animals living in northern Italy, sampled at a time of frequent human infection. No animals tested PCR positive. However, 3.3% of dogs and 5.8% of cats had measurable SARS-CoV-2 neutralizing antibody titers, with dogs from COVID-19 positive households being significantly more likely to test positive than those from COVID-19 negative households. Understanding risk factors associated with this and their potential to infect other species requires urgent investigation.

Significance: Factors influencing Wolbachia transfer into new species remain poorly understood. This is important as Wolbachia can influence speciation and is being developed as a novel arthropod-borne disease control approach. We show the native microbiota of Anopheles impede vertical transmission of Wolbachia . Antibiotic microbiome perturbation enables Wolbachia transmission in two Anopheles species. Mosquitoes with altered microbiomes do not exhibit blood meal-induced mortality associated with Wolbachia infection, suggesting that mosquitoes are killed by interactions between Wolbachia and other bacteria present in the mosquito. We identified Asaia as the bacterium responsible for inhibiting Wolbachia transmission, and partially responsible for blood meal-induced mortality. These results suggest that microbial interactions profoundly affect the host, and that microbiome incompatibility may influence distribution of Wolbachia in arthropods.

The scientific community has responded to the coronavirus disease 2019 (COVID-19) pandemic by rapidly undertaking research to find effective strategies to reduce the burden of this disease. Encouragingly, researchers from a diverse array of fields are collectively working towards this goal. Research with infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is undertaken in high-containment laboratories; however, it is often desirable to work with samples at lower-containment levels. To facilitate the transfer of infectious samples from high-containment laboratories, we have tested methods commonly used to inactivate virus and prepare the sample for additional experiments. Incubation at 80°C, a range of detergents, Trizol reagents, and UV energies were successful at inactivating a high titer of SARS-CoV-2. Methanol and paraformaldehyde incubation of infected cells also inactivated the virus. These protocols can provide a framework for in-house inactivation of SARS-CoV-2 in other laboratories, ensuring the safe use of samples in lower-containment levels.