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Background: Canine leishmaniasis (CanL) is caused by Leishmania infantum (L. infantum) that is transmitted by sand fly vectors with dogs acting as the main reservoir. Methods: The present study aimed to determine the seroprevalence of CanL in dogs from Egypt and assessed the associated risk factors. The study was conducted from 2019 to 2020 in five governorates situated in Northern Egypt. Serum samples from 450 asymptomatic dogs were serologically examined by use of enzyme-linked immunosorbent assay (ELISA). Results: Overall, the seroprevalence rate of CanL was 21.3% and the highest rates were observed in Cairo and Giza governorates. The univariable analysis revealed that the seropositivity of CanL was strongly related to the dogs' ages, length of hair, absence of veterinary care or application of insecticides, and the type of floor of their shelters. The risk factors that were found to be associated with CanL in exposed dogs were: age group 2-4 years old (OR = 12, 95% CI: 1.6-92.3); short hair (OR = 2.07, 95% CI: 1.2-3.6); absence of veterinary care (OR = 2.7, 95% CI: 1.3-5.8); no application of insecticides (OR = 3.09, 95% CI: 1.5-6.5) and their residence in a shelter with an earthen floor (OR = 1.42, 95% CI: 0.7-2.9). Conclusions: Based on the present results, CanL is present in Egyptian dogs and this increases the possibility of transmission by sand fly to humans with whom they have contact. Consequently, an efficient monitoring programme and effective control measures are important to reduce the risk of infection. [ABSTRACT FROM AUTHOR]

Background: The Middle East respiratory syndrome coronavirus (MERS-CoV) is a highly pathogenic zoonotic betacoronavirus and a global public health concern. Better undersetting of the immune responses to MERS-CoV is needed to characterize the correlates of protection and durability of the immunity and to aid in developing preventative and therapeutic interventions. Although MERS-CoV-specific circulating antibodies could persist for several years post-recovery, their waning raises concerns about their durability and role in protection. Nonetheless, memory B and T cells could provide long-lasting protective immunity despite the serum antibodies levels., Methods: Serological and flow cytometric analysis of MERS-CoV-specific immune responses were performed on samples collected from a cohort of recovered individuals who required intensive care unit (ICU) admission as well as hospital or home isolation several years after infection to characterize the longevity and quality of humoral and cellular immune responses., Results: Our data showed that MERS-CoV infection could elicit robust long-lasting virus-specific binding and neutralizing antibodies as well as T- and B-cell responses up to 6.9 years postinfection regardless of disease severity or need for ICU admission. Apart from the persistent high antibody titers, this response was characterized by B-cell subsets with antibody-independent functions as demonstrated by their ability to produce tumor necrosis factor α (TNF-α), interleukin (IL)-6, and interferon γ (IFN-γ) cytokines in response to antigen stimulation. Furthermore, virus-specific activation of memory CD8+ and CD4+ T cell subsets from MERS-recovered patients resulted in secretion of high levels of TNF-α, IL-17, and IFN-γ., Conclusions: MERS-CoV infection could elicit robust long-lasting virus-specific humoral and cellular responses., Competing Interests: Potential conflicts of interest. A. M. H. reports consultation fees from SaudiVax ltd and US10849972B2 patent (Trimeric S1-CD40L fusion protein vaccine against Middle East respiratory syndrome-coronavirus), US10806784B1 patent (composition and method for treating MERS), US11154612B2 patent (MERS-CoV vaccine with trimeric S1-CD40L fusion protein), US11219685B1 patent (Intranasal MERS-CoV vaccine), US20220008530A1 patent application (MERS-CoV VACCINE COMPOSITION), US20220054629A1 patent application (nucleic acid based vaccine against middle east respiratory syndrome-coronavirus). All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2022. Published by Oxford University Press on behalf of Infectious Diseases Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Phlebotomine sand flies transmit the haemoflagellate Leishmania, the causative agent of human leishmaniasis. The Leishmania promastigotes are confined to the gut lumen and are exposed to the gut microbiota within female sand flies. Here we study the colonisation resistance of yeast and bacteria in preventing the establishment of a Leishmania population in sand flies and the ability of Leishmania to provide colonisation resistance towards the insect bacterial pathogen Serratia marcescens that is also pathogenic towards Leishmania., Methods: We isolated microorganisms from wild-caught and laboratory-reared female Lutzomyia longipalpis, identified as Pseudozyma sp. Asaia sp. and Ochrobactrum intermedium. We fed the females with a sugar meal containing the microorganisms and then subsequently fed them with a bloodmeal containing Leishmania mexicana and recorded the development of the Leishmania population. Further experiments examined the effect of first colonising the sand fly gut with L. mexicana followed by feeding with, Serratia marcescens, an insect bacterial pathogen. The mortality of the flies due to S. marcescens was recorded in the presence and absence of Leishmania., Results: There was a reduction in the number of flies harbouring a Leishmania population that had been pre-fed with Pseudozyma sp. and Asaia sp. or O. intermedium. Experiments in which L. mexicana colonised the sand fly gut prior to being fed an insect bacterial pathogen, Serratia marcescens, showed that the survival of flies with a Leishmania infection was significantly higher compared to flies without Leishmania infection., Conclusions: The yeast and bacterial colonisation experiments show that the presence of sand fly gut microorganisms reduce the potential for Leishmania to establish within the sand fly vector. Sand flies infected with Leishmania were able to survive an attack by the bacterial pathogen that would have killed the insect and we concluded that Leishmania may benefit its insect host whilst increasing the potential to establish itself in the sand fly vector. We suggest that the increased ability of the sand fly to withstand a bacterial entomopathogen, due to the presence of the Leishmania, may provide an evolutionary pressure for the maintenance of the Leishmania-vector association.