Lassa virus in novel hosts: insights into the epidemiology of lassa virus infections in southern Nigeria

Identification of the diverse animal hosts responsible for spill-over events from animals to humans is crucial for comprehending the transmission patterns of emerging infectious diseases, which pose significant public health risks. To better characterize potential animal hosts of Lassa virus (LASV), we assessed domestic and non-domestic animals from 2021-2022 in four locations in southern Nigeria with reported cases of Lassa fever (LF). Birds, lizards, and domestic mammals (dogs, pigs, cattle and goats) were screened using RT-qPCR, and whole genome sequencing was performed for lineage identification on selected LASV positive samples. Animals were also screened for exposure to LASV by enzyme-linked immunosorbent assay (ELISA). Among these animals, lizards had the highest positivity rate by PCR. Genomic sequencing of samples in most infected animals showed sub-lineage 2 g of LASV. Seropositivity was highest among cattle and lowest in pigs. Though the specific impact these additional hosts may have in the broader virus-host context are still unknown - specifically relating to pathogen diversity, evolution, and transmission - the detection of LASV in non-rodent hosts living in proximity to confirmed human LF cases suggests their involvement during transmission as potential reservoirs. Additional epidemiological data comparing viral genomes from humans and animals, as well as those circulating within the environment will be critical in understanding LASV transmission dynamics and will ultimately guide the development of countermeasures for this zoonotic health threat.

Food and Water Insecurity in Sexual and Gender Minority Groups Living With HIV in Lagos, Nigeria

BACKGROUND

Food and water insecurity are associated with poor health outcomes that may be exacerbated by social marginalization and barriers to health care experienced by sexual and gender minorities (SGM) in resource-limited settings. We explored factors associated with food and water insecurity in SGM with HIV.

SETTING

A longitudinal study of 357 men who have sex with men, transgender women, and other gender-identifying people in Lagos, Nigeria.

METHODS

Laboratory testing, interviews, food and water assessments, and anthropometry were performed quarterly. Robust Poisson regression with generalized estimating equations was used to evaluate factors potentially associated with food and water insecurity.

RESULTS

From 2014 to 2018, 357 SGM with HIV completed either the food or water assessments. At baseline, participants identified as cisgender men who have sex with men 265 (74.2%), transgender women 63 (17.7%), or as nonbinary/other gender 29 (8.1%). Food insecurity and water insecurity were reported by 63/344(18.3%) and 113/357(31.7%), respectively, at any visit. Food and water insecurity each decreased with ongoing study participation. Food insecurity was associated with nonpartnered relationship status, CD4 count <500 cells/mm 3 , and lack of access to piped water. Water insecurity was associated with age 25 years or older, living with a man, transactional sex, and food insecurity.

CONCLUSIONS

Food and water insecurity were common among SGM in Nigeria and decreased with continued study participation, suggesting amenability to intervention when SGM are successfully engaged in care. Targeted interventions to support food and water security may improve HIV-related outcomes, such as CD4 count.

Transmitted, pre-treatment and acquired antiretroviral drug resistance among men who have sex with men and transgender women living with HIV in Nigeria

BACKGROUND

Across sub-Saharan Africa, men who have sex with men (MSM) and transgender women (TGW) have disproportionately poor HIV treatment outcomes. Stigma and criminalization create barriers to health-care engagement and adherence to antiretroviral therapy (ART), potentially promoting the development of HIV drug resistance (HIVDR). We evaluated transmitted, pre-treatment and acquired HIVDR among MSM and TGW in Lagos and Abuja, Nigeria.

METHODS

Adults with HIV RNA ≥1,000 copies/ml in the TRUST/RV368 cohort, including incident cases diagnosed via 3-monthly screening, underwent HIVDR testing using the Sanger sequencing method. Major mutations conferring resistance to nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs) and protease inhibitors (PIs) were identified from the 2017 IAS-USA list. World Health Organization surveillance drug resistance mutations (SDRMs) were identified in ART-naive participants.

RESULTS

From March 2013 to June 2017, 415 participants with median age 24 (interquartile range [IQR] 21-27) years, CD4⁺ T-cell count 370 (IQR 272-502) cells/mm³, and HIV RNA 4.73 (IQR 4.26-5.15) log₁₀ copies/ml underwent HIVDR testing. SDRMs were observed in 36 of 373 ART-naive participants (9.7%, 95% confidence interval [95% CI 6.8, 13.1%]), including 8 of 39 incident cases (20.5%, [95% CI] 9.3, 36.5%). Among 42 ART-experienced participants, NNRTI resistance was detected in 18 (42.9%, 95% CI 27.7, 59.0%) and NRTI resistance in 10 (23.8%, 95% CI 12.0, 39.4%). No PI resistance was detected.

CONCLUSIONS

The high prevalence of transmitted and acquired drug resistance among Nigerian MSM and TGW living with HIV suggests the need for programmatic solutions to improve uninterrupted access to ART and timely switch to second-line regimens in cases of viral failure.

Platelet Factor 4 Inhibits and Enhances HIV-1 Infection in a Concentration-Dependent Manner by Modulating Viral Attachment

Platelet factor 4 (PF4) has been recently shown to inhibit infection by a broad range of human immunodeficiency virus type 1 (HIV-1) isolates in vitro. We found that the inhibitory effects of PF4 are limited to a defined concentration range where PF4 exists largely in a monomeric state. Under these conditions, PF4 bound the HIV-1 envelope protein and inhibited HIV-1 attachment to the cell surface. However, as concentrations increased to the point where PF4 exists largely in tetrameric or higher-order forms, viral infection in vitro was enhanced. Enhancement could be inhibited by mutations in PF4 that shift the oligomeric equilibrium toward the monomeric state, or by using soluble glycosaminoglycans (GAGs) to which tetrameric PF4 avidly binds. We conclude that at physiologically relevant concentrations, oligomeric PF4 enhances infection by HIV-1 by interacting with the viral envelope protein as well as cell surface GAGs, enhancing virus attachment to the cell surface. This effect was not specific to HIV-1, as enhancement was seen with some but not all other viruses tested. The biphasic effects of PF4 on HIV-1 infection suggest that native PF4 will not be a useful antiviral agent and that PF4 could contribute to the hematologic abnormalities commonly seen in HIV-infected individuals by enhancing virus infection in the bone marrow.

Immuno-chromatographic wicking assay for the rapid detection of dengue viral antigens in mosquitoes (Diptera: Culicidae)

There is a threat for dengue virus (DENV) reemergence in many regions of the world, particularly in areas where the DENV vectors, Aedes aegypti (L.) and Aedes albopictus (Skuse), are readily available. However, there are currently no accurate and reliable diagnostic methods to provide critical, real-time information for early detection of DENV within the vector populations to implement appropriate vector control and personal protective measures. In this article, we report the ability of an immuno-chromatographic assay developed by VecTOR Test Systems Inc. to detect DENV in a pool of female Aedes mosquitoes infected with any of the four viral serotypes. The DENV dipstick assay was simple to use, did not require a cold chain, and provided clear results within 30 min. It was highly specific and did not cross-react with samples spiked with West Nile, yellow fever, Japanese encephalitis, Rift Valley fever, chikungunya, Venezuelan equine encephalomyelitis, Ross River, LaCrosse, or Caraparu viruses. The DENV assay can provide real-time critical information on the presence of DENV in mosquitoes to public health personnel. Results from this assay will allow a rapid threat assessment and the focusing of vector control measures in high-risk areas.