Detoxification enzymes associated with insecticide resistance in laboratory strains of Anopheles arabiensis of different geographic origin

Background The use of insecticides to control malaria vectors is essential to reduce the prevalence of malaria and as a result, the development of insecticide resistance in vector populations is of major concern. Anopheles arabiensis is one of the main African malaria vectors and insecticide resistance in this species has been reported in a number of countries. The aim of this study was to investigate the detoxification enzymes that are involved in An. arabiensis resistance to DDT and pyrethroids. Methods The detoxification enzyme profiles were compared between two DDT selected, insecticide resistant strains of An. arabiensis, one from South Africa and one from Sudan, using the An. gambiae detoxification chip, a boutique microarray based on the major classes of enzymes associated with metabolism and detoxification of insecticides. Synergist assays were performed in order to clarify the roles of over-transcribed detoxification genes in the observed resistance phenotypes. In addition, the presence of kdr mutations in the colonies under investigation was determined. Results The microarray data identifies several genes over-transcribed in the insecticide selected South African strain, while in the Sudanese population, only one gene, CYP9L1, was found to be over-transcribed. The outcome of the synergist experiments indicate that the over-transcription of detoxification enzymes is linked to deltamethrin resistance, while DDT and permethrin resistance are mainly associated with the presence of the L1014F kdr mutation. Conclusions These data emphasise the complexity associated with resistance phenotypes and suggest that specific insecticide resistance mechanisms cannot be extrapolated to different vector populations of the same species

DDT and pyrethroid resistance in Anopheles arabiensis from South Africa

BACKGROUND: Pyrethroid resistance has been well documented in Anopheles arabiensis, one of the major African malaria vectors, and the predominant malaria vector in South Africa. METHODS: In this study, the genetic basis of pyrethroid resistance in a selected laboratory strain of An. arabiensis from South Africa was investigated using a custom-made microarray, known as the An. gambiae detoxification chip. RESULTS: A large number of P450 genes were over-transcribed, as well as a suite of redox genes and glutathione S-transferases. The five genes that showed the highest level of gene transcription when compared with an insecticide susceptible strain were: CYP6AG2, CYPZ1, TPX2, CYPZ2 and CYP6P1. CONCLUSIONS: Permethrin resistance in South African An. arabiensis is associated with increased transcription of multiple genes, and a large proportion of these genes were also previously recorded as over-transcribed in another An. arabiensis strain selected for resistance to DDT with cross-resistance to deltamethrin. The deltamethrin resistance developed de novo in the DDT-selected strain and is most likely due to increased transcription of those genes associated with DDT resistance. However, of particular interest was the fact that the strain selected for resistance to pyrethroids did not develop de novo resistance to DDT. These differences are compared and discussed.National Research Foundation Scarce Skills Scholarships and DAAD (LN), National Research Foundation and the National Health Laboratory Service-Research Trust to LLK, partial funding from the Department of Science and Technology, National Research Foundation Research Chair Initiative grant to Maureen Coetzee.http://www.parasitesandvectors.com/content/6/1/229am201

DDT and pyrethroid resistance in Anopheles arabiensis from South Africa

BACKGROUND: Pyrethroid resistance has been well documented in Anopheles arabiensis, one of the major African malaria vectors, and the predominant malaria vector in South Africa. METHODS: In this study, the genetic basis of pyrethroid resistance in a selected laboratory strain of An. arabiensis from South Africa was investigated using a custom-made microarray, known as the An. gambiae detoxification chip. RESULTS: A large number of P450 genes were over-transcribed, as well as a suite of redox genes and glutathione S-transferases. The five genes that showed the highest level of gene transcription when compared with an insecticide susceptible strain were: CYP6AG2, CYPZ1, TPX2, CYPZ2 and CYP6P1. CONCLUSIONS: Permethrin resistance in South African An. arabiensis is associated with increased transcription of multiple genes, and a large proportion of these genes were also previously recorded as over-transcribed in another An. arabiensis strain selected for resistance to DDT with cross-resistance to deltamethrin. The deltamethrin resistance developed de novo in the DDT-selected strain and is most likely due to increased transcription of those genes associated with DDT resistance. However, of particular interest was the fact that the strain selected for resistance to pyrethroids did not develop de novo resistance to DDT. These differences are compared and discussed.National Research Foundation Scarce Skills Scholarships and DAAD (LN), National Research Foundation and the National Health Laboratory Service-Research Trust to LLK, partial funding from the Department of Science and Technology, National Research Foundation Research Chair Initiative grant to Maureen Coetzee.http://www.parasitesandvectors.com/content/6/1/229am201

Variable contribution identification and visualization in multivariate statistical process monitoring

CITATION: Rossouw, R. F.; Coetzer, R. L. J. & Le Roux, N. J. 2020. Variable contribution identification and visualization in multivariate statistical process monitoring. Chemometrics and Intelligent Laboratory Systems, 198. doi:10.1016/j.chemolab.2019.103894The original publication is available at https://www.sciencedirect.com/journal/chemometrics-and-intelligent-laboratory-systemsMultivariate statistical process monitoring (MSPM) has received book-length treatments and wide spread application in industry. In MSPM, multivariate data analysis techniques such as principal component analysis (PCA) are commonly employed to project the (possibly many) process variables onto a lower dimensional space where they are jointly monitored given a historical or specified reference set that is within statistical control. In this paper, PCA and biplots are employed together in an innovative way to develop an efficient multivariate process monitoring methodology for variable contribution identification and visualization. The methodology is applied to a commercial coal gasification production facility with multiple parallel production processes. More specifically, it is shown how the methodology is used to specify the optimal principal component combinations and biplot axes for visualization and interpretation of process performance, and for the identification of the critical variables responsible for performance deviations, which yielded direct benefits for the commercial production facility.https://www.sciencedirect.com/science/article/pii/S0169743919305088?via%3DihubPublishers versio

Drug resistance and viral tropism in HIV-1 subtype C-infected patients in KwaZulu-Natal, South Africa: implications for future treatment options

Article approval pendingDrug resistance poses a significant challenge for the successful application of highly active antiretroviral therapy (HAART) globally. Furthermore, emergence of HIV-1 isolates that preferentially use CXCR4 as a coreceptor for cell entry, either as a consequence of natural viral evolution or HAART use, may compromise the efficacy of CCR5 antagonists as alternative antiviral therapy

Insecticide resistance and the future of malaria control in Zambia.

BACKGROUND: In line with the Global trend to improve malaria control efforts a major campaign of insecticide treated net distribution was initiated in 1999 and indoor residual spraying with DDT or pyrethroids was reintroduced in 2000 in Zambia. In 2006, these efforts were strengthened by the President's Malaria Initiative. This manuscript reports on the monitoring and evaluation of these activities and the potential impact of emerging insecticide resistance on disease transmission. METHODS: Mosquitoes were captured daily through a series of 108 window exit traps located at 18 sentinel sites. Specimens were identified to species and analyzed for sporozoites. Adult Anopheles mosquitoes were collected resting indoors and larva collected in breeding sites were reared to F1 and F0 generations in the lab and tested for insecticide resistance following the standard WHO susceptibility assay protocol. Annual cross sectional household parasite surveys were carried out to monitor the impact of the control programme on prevalence of Plasmodium falciparum in children aged 1 to 14 years. RESULTS: A total of 619 Anopheles gambiae s.l. and 228 Anopheles funestus s.l. were captured from window exit traps throughout the period, of which 203 were An. gambiae malaria vectors and 14 An. funestus s.s.. In 2010 resistance to DDT and the pyrethroids deltamethrin, lambda-cyhalothrin and permethrin was detected in both An. gambiae s.s. and An. funestus s.s.. No sporozoites were detected in either species. Prevalence of P. falciparum in the sentinel sites remained below 10% throughout the study period. CONCLUSION: Both An. gambiae s.s. and An. funestus s.s. were controlled effectively with the ITN and IRS programme in Zambia, maintaining a reduced disease transmission and burden. However, the discovery of DDT and pyrethroid resistance in the country threatens the sustainability of the vector control programme

Serological evidence of Rift Valley fever virus circulation in sheep and goats in Zambezia Province, Mozambique

Rift Valley fever (RVF) is endemic in most parts of Africa and has also been reported to occur in the Arabian Peninsula. It is responsible for significant morbidity and mortality, particularly in livestock, but also in humans. During the last two decades several outbreaks of RVF have been reported in countries in Southern Africa. In contrast to other countries, no clinical disease has been reported in Mozambique during this period. In a serological study conducted in 2007 in five districts of Zambe´zia Province, Mozambique, of a total of 654 small ruminants sampled (277 sheep and 377 goats), 35.8% of sheep sera and 21.2% of goat sera were positive for RVF virus (RVFV) antibodies in a virus neutralization test (VN) and in an IgG enzymelinked immunosorbent assay (ELISA). In 2010, a cross-sectional survey was conducted in 313 sheep and 449 goats in two districts of the same province. This study revealed an overall seropositivity rate of 9.2% in sheep and 11.6% in goat and an increased likelihood of being seropositive in older animals (OR = 7.3; p,0.001) using an IgG ELISA. 29 out of 240 animals assessed for RVF specific IgM by ELISA were positive, suggesting recent exposure to RVFV. However, a longitudinal study carried out between September 2010 and April 2011 in a cohort of 125 of these animals (74 sheep and 51 goats) failed to demonstrate seroconversion. The results of the study indicate that RVFV circulates sub-clinically in domestic small ruminants in Zambe´ zia Province.The work was supported by the SIDA/SAREC project UEM, the Italian Project at the Biotechnology Center – UEM (AID 9397), and by the Utrecht University, The Netherlands.http://www.plosntds.orgam2014ab201

The use of dog collars offers significant benefits to rabies vaccination campaigns : the case of Zanzibar, Tanzania

SUPPLEMENTARY MATERIAL : FILE S1: Questionnaire used during the KAP survey in Zanzibar. FILE S2: Overview of the vaccination date and survey date for each ward included in the study. FILE S3: Supplementary tables derived from the data collected in this study.DATA AVAILABILITY STATEMENT : The survey data file is available from the Open Science Framework database (https://osf.io/56wkj/) (accessed on 27 July 2023).Tools and resources that could increase dog vaccination coverage have become increasingly critical towards progressing the goal to eliminate dog-mediated human rabies by 2030. In this regard, dog collars that are fitted during vaccination campaigns could potentially enhance owner participation. The use of dog collars will, however, increase the cost per dog vaccinated and the impact and benefit of this practice should be elucidated. This study evaluated the impact of dog collars by testing the perception and related behavioural influences in communities in Zanzibar. In this cross-sectional investigation—conducted approximately two months after the implementation of a mass dog vaccination (MDV) where dog collars were provided to vaccinated dogs—data were collected from 600 respondents in 56 municipal wards in Zanzibar. Descriptive analyses and logistic regressions were undertaken to determine the impact the collars had on respondents with regards to (i) engaging with the community dogs, (ii) health seeking behaviour after exposure, and (iii) overall participation during dog vaccination campaigns. From the data, it was evident that the collars had a positive impact on the community’s perception of dogs, with 57% of the respondents feeling safer around a dog with a collar, while 66% of the respondents felt less safe around a dog without a collar. Furthermore, the collars had a positive impact on participation during dog vaccination campaigns. Of the 142 respondents who owned dogs, 64% reported that the collars made them more likely to take their dogs for vaccination, and 95% felt that the collar was an important sign of the dog’s vaccination status. This study demonstrated that dog collars could not only improve participation during dog vaccination campaigns, but that they could also play a significant role in the community’s perception of rabies vaccination campaigns and vaccinated dogs in general.Boehringer Ingelheim.https://www.mdpi.com/journal/tropicalmedam2023BiochemistryGeneticsMicrobiology and Plant PathologySDG-03:Good heatlh and well-bein

Cognition in schizophrenia improves with treatment of severe obstructive sleep apnoea: a pilot study

Previous studies have shown that people with schizophrenia have high rates of Obstructive Sleep Apnoea (OSA). Despite this, intervention studies to treat OSA in this population have not been undertaken. The ASSET (Assessing Sleep in Schizophrenia and Evaluating Treatment) pilot study investigated Continuous Positive Airway Pressure (CPAP) treatment of severe OSA in participants recruited from a clozapine clinic in Adelaide. Participants with severe untreated OSA (Apnoea-Hypopnoea Index (AHI) > 30), were provided with CPAP treatment, and assessed at baseline and six months across the following domains: physical health, quality of sleep, sleepiness, cognition, psychiatric symptoms and CPAP adherence. Six of the eight ASSET participants with severe OSA accepted CPAP. At baseline, half of the cohort had hypertension, all were obese with a mean BMI of 45, and they scored on average 1.47 standard deviations below the normal population in cognitive testing. The mean AHI was 76.8 and sleep architecture was markedly impaired with mean rapid eye movement (REM) sleep 4.1% and mean slow wave sleep (SWS) 4.8%. After six months of treatment there were improvements in cognition (BACS Z score improved by an average of 0.59) and weight loss (mean weight loss 7.3 ± 9 kg). Half of the participants no longer had hypertension and sleep architecture improved with mean REM sleep 31.4% of the night and mean SWS 24% of the night. Our data suggests CPAP may offer novel benefits to address cognitive impairment and sleep disturbance in people with schizophrenia.Hannah Myles, Nicholas Myles, Ching Li Chai Coetzer, Robert Adams, Madhu Chandratilleke, Dennis Liu, Jeremy Mercer, Andrew Vakulin, Andrew Vincent, Gary Wittert, Cherrie Galletl