Genomic and microscopic evidence of stable high density and maternally inherited <i>Wolbachia</i> infections in <i>Anopheles</i> mosquitoes

AbstractWolbachia, a widespread bacterium that can reduce pathogen transmission in mosquitoes, has been detected within populations of Anopheles (An.) malaria vectors. In the An. gambiae complex, the primary vectors in Sub-Saharan Africa, Wolbachia strains are at low density and infection frequencies in wild populations. PCR-independent evidence is required to determine whether Wolbachia strains are true endosymbionts in Anopheles given most studies to date have used nested-PCR to identify strains. Here we report high-density strains found in geographically diverse populations of An. moucheti and An. demeilloni. Fluorescent in situ hybridization localized a heavy infection in the ovaries of An. moucheti and maternal transmission was observed. Genome sequencing of both strains obtained genome depths and coverages comparable to other known infections. Notably, homologs of cytoplasmic incompatibility factor (cif) genes were present indicating these strains possess the capacity to induce the phenotype cytoplasmic incompatibility which allows Wolbachia to spread through populations. The characteristics of these two strains suggest they are ideal candidates for Wolbachia biocontrol strategies in Anopheles.</jats:p

Long‐term persistence of neutralizing SARS‐CoV‐2 antibodies in pets

We monitored the severe acute respiratory syndrome coronavirus 2 antibody response in seven dogs and two cats by using two multispecies ELISA tests, plaque reduction neutralisation test and virus neutralization. SARS-CoV-2 neutralizing antibodies in pets persisted up to 10 months since the first positive testing, thus replicating observations in COVID-19 human patients

Microbial interactions in the mosquito gut determineSerratiacolonization and blood-feeding propensity

How microbe–microbe interactions dictate microbial complexity in the mosquito gut is unclear. Previously we found that, Serratia, a gut symbiont that alters vector competence and is being considered for vector control, poorly colonized Aedes aegypti yet was abundant in Culex quinquefasciatus reared under identical conditions. To investigate the incompatibility between Serratia and Ae. aegypti, we characterized two distinct strains of Serratia marcescens from Cx. quinquefasciatus and examined their ability to infect Ae. aegypti. Both Serratia strains poorly infected Ae. aegypti, but when microbiome homeostasis was disrupted, the prevalence and titers of Serratia were similar to the infection in its native host. Examination of multiple genetically diverse Ae. aegypti lines found microbial interference to S. marcescens was commonplace, however, one line of Ae. aegypti was susceptible to infection. Microbiome analysis of resistant and susceptible lines indicated an inverse correlation between Enterobacteriaceae bacteria and Serratia, and experimental co-infections in a gnotobiotic system recapitulated the interference phenotype. Furthermore, we observed an effect on host behavior; Serratia exposure to Ae. aegypti disrupted their feeding behavior, and this phenotype was also reliant on interactions with their native microbiota. Our work highlights the complexity of host–microbe interactions and provides evidence that microbial interactions influence mosquito behavior

SARS-CoV-2 neutralising antibodies in Dogs and Cats in the United Kingdom.

Companion animals are susceptible to SARS-CoV-2 infection and sporadic cases of pet infections have occurred in the United Kingdom. Here we present the first large-scale serological survey of SARS-CoV-2 neutralising antibodies in dogs and cats in the UK. Results are reported for 688 sera (454 canine, 234 feline) collected by a large veterinary diagnostic laboratory for routine haematology during three time periods; pre-COVID-19 (January 2020), during the first wave of UK human infections (April-May 2020) and during the second wave of UK human infections (September 2020-February 2021). Both pre-COVID-19 sera and those from the first wave tested negative. However, in sera collected during the second wave, 1.4% (n=4) of dogs and 2.2% (n=2) cats tested positive for neutralising antibodies. The low numbers of animals testing positive suggests pet animals are unlikely to be a major reservoir for human infection in the UK. However, continued surveillance of in-contact susceptible animals should be performed as part of ongoing population health surveillance initiatives

Pairwisde beta diversity metrics for the <i>Ae</i>. <i>aegypti</i> lines reared at the LSTM and UTMB insectaries.

The dissimilarities between the pairs of lines of Ae. aegypti at each insectary were analyzed by principal component analysis of Bray-Curtis dissimilarity index. PERMANOVA analysis, LSTM: Iquitos vs Thailand p-value = 0.001, Juchitan vs Thailand p-value = 0.001, Iquitos vs Thailand p-value = 0.001, Galveston vs Thailand p-value = 0.001, Galveston vs Juchitan p-value = 0.001, Galveston vs Iquitos p-value = 0.001. UTMB: Iquitos vs Thailand p-value = 0.001, Juchitan vs Thailand p-value = 0.001, Iquitos vs Thailand p-value = 0.001, Galveston vs Thailand p-value = 0.001, Galveston vs Juchitan p-value = 0.001, Galveston vs Iquitos p-value = 0.001.) (TIF)</p

Heatmap showing the correlation between bacterial taxa co-occurrence between the different mosquito strains and rearing insectaries.

Saturated greens indicate strong co-occurrence between the bacteria taxa, while saturated purple indicates strong exclusion, and whites indicate no positive or negative correlation. We show that Klebsiella co-occurs with Enterobacter taxa, whilst Serratia and Cedecea taxa appear to exclude other bacterial taxa. (TIF)</p

Alpha and beta diversity metrics for the <i>Ae</i>. <i>aegypti</i> lines reared at the LSTM and UTMB insectaries.

(A, C): The species richness (Chao1 index) was calculated from 20 individuals from each line (Galveston, Thailand, Iquitos, Juchitan) at each insectary. The level of species richness differed between individuals from the LSTM (ANOVA, p-value Ae. aegypti was analyzed by principal component analysis of Bray-Curtis dissimilarity index. The bacterial community structure of the lines differed in individuals from LSTM (PERMANOVA, p-value = 0.001) and UTMB (PERMANOVA, p-value = 0.001).</p

Diversity of the microbiome in individuals reared at the LSTM or UTMB insectaries.

Structure of bacterial communities was determined by deep sequencing the V3-V4 region of the bacterial 16S gene in adults from 4 different lines of Ae aegypti (Galveston, Thailand, Iquitos, Juchitan) reared in two different insectaries at UTMB and LSTM. The Bacterial community structure is represented (A) by the species richness index Chao1 and (B) by principal component analysis of Bray-Curtis dissimilarity index. Mosquito lines reared at LSTM are shown in purple, mosquitoes reared to UTMB are shown in turquoise.</p

Pairwise comparisons of mosquito lines reared in each insectary.

The microbiomes of mosquito lines reared in the same insectary are more similar compared to those reared in a different insectary. Results from a pairwise differential abundance analysis are shown for each pair of lines as the percent of genera that are significantly different between the pairs after correcting for multiple comparisons. A light blue color indicates a higher degree of dissimilarity between the lines.</p

Relative abundance of bacteria in each line.

The dominant bacterial genera are different between insectaries and between lines. The relative abundance of the 20 most abundant genera in shown for 20 individuals from each line at LSTM and UTMB insectaries. Bacterial genera were assigned to OTUs clustered with a 97% sequence identity cutoff and taxonomically classified with the SILVA database.</p