Risque de transmission de certains arbovirus à travers le don de sang à Bamako / Risk of transmission of certain arbovirus through blood donation in the city of Bamako

Introduction. Au Mali, le dépistage de certains virus tels que la dengue, Zika et la fièvre de la vallée du Rift n'est pas systématique au centre national de transfusion sanguine (CNTS). Le risque peut être considérable en raison de leurs courtes périodes de virémie asymptomatique dans la population dont l'incidence est variable et parfois extrêmement élevée. Cette étude avait pour objectif d'explorer la possibilité de transmission de certains arbovirus à travers le don de sang au CNTS de Bamako. Méthodes. Il s'agissait d'une étude transversale, de juillet 2019 à juin 2020 à Bamako. Au total deux cents (200) donneurs de sang du CNTS ont été inclus. Les examens ont été réalisés au Centre d'Infectiologie Charles Mérieux (CICM) de Bamako avec le dépistage du génome des virus responsables de la Dengue, de la fièvre de la Vallée du Rift, et du Zika à l'aide de la technique de la RT-PCR en temps réel. Le Test de Dépistage Rapide (TDR) a été utilisé pour la détection des anticorps IgG et IgM spécifiques de la Dengue. Résultats. Le sexe masculin représente 84% (168/200). Le TDR a détecté 4,5% (9/200) de Dengue IgG positifs et aucun cas de Dengue IgM positif. La technique de RT-PCR n'a détecté aucun des trois virus. Conclusion. Cette étude prouve que le risque de transmission de certains arbovirus à travers le don de sang existe, mais il semble être minime au CNTS de Bamako

Background. In Mali, screening for certain viruses such as dengue, Zika, and Rift Valley fever is not systematic at the national blood transfusion center (CNTS). The risk can be considerable due to their short periods of asymptomatic viremia in the population with variable and sometimes extremely high incidence. The objective of this study was to explore the possibility of transmission of certain arboviruses through blood donation at the CNTS of Bamako. Methods. This was a cross-sectional study, from July 2019 to June 2020 in Bamako. A total of two hundred (200) blood donors from the CNTS were included. The examinations were performed at the Centre d'Infectiologie Charles Mérieux (CICM) in Bamako with the screening of the genome of viruses responsible for Dengue, Rift Valley fever, and Zika using the real-time RT-PCR technique. The Rapid Screening Test (RST) was used for the detection of Dengue-specific IgG and IgM antibodies. Results. Male sex represented 84% (168/200). The RDT detected 4.5% (9/200) of IgG positive Dengue and no IgM positive Dengue cases. The RT-PCR technique did not detect any of the three viruses. Conclusion. This study proves that the risk of transmission of certain arboviruses through blood donation exists, but it seems to be minimal at the CNTS of Bamako.

Effect Of Sodium Nitrite Exposure On The Immune Responses Against Of Rift Valley Fever Vaccine In Mice

Objective: Daily exposure to food preservatives constitutes a major crisis to children especially during vaccination so; the aim of the study is to assess the effect of sodium nitrite on the immune responses against Rift Valley fever vaccine (RVFV) in Swiss mice. Methods: Mice were divided into four equal groups: group 1 (control) was orally administrated with distilled water (2 ml/kg b. wt.); group 2 was orally administrated with the acceptable daily intake (ADI) of sodium nitrite 0.07 mg/kg b. wt. daily for 21 d, group 3 was vaccinated with inactivated RVFV two times and group 4 was orally given sodium nitrite and vaccinated as group 3. Blood samples were collected from all groups two weeks after booster vaccination. The leucocytic indices and the neutrophil-lymphocyte ratio (NLR) were determined to assess the cell-mediated immunity. The humoral immunity was evaluated using direct enzyme-linked immune-sorbent assay (ELISA) test and serum neutralization test (SNT). Results: Sodium nitrite significantly increased the neutrophil index and the NLR whereas; it decreased the total leucocytic count and lymphocyte index in both non-vaccinated and vaccinated mice. Moreover, sodium nitrite significantly decreased both the IgG titer and the efficiency of vaccination through increasing the ED50 value. Conclusion: Sodium nitrite existed an immune-suppressive effect on both cellular and humoral immune responses in mice.

Packaging of Rift Valley fever virus pseudoviruses and establishment of a neutralization assay method

Rift Valley fever (RVF) is an acute, febrile zoonotic disease that is caused by the RVF virus (RVFV). RVF is mainly prevalent on the Arabian Peninsula, the African continent, and several islands in the Indian Ocean near southeast Africa. RVFV has been classified by the World Organisation for Animal Health (OIE) as a category A pathogen. To avoid biological safety concerns associated with use of the pathogen in RVFV neutralization assays, the present study investigated and established an RVFV pseudovirus-based neutralization assay. This study used the human immunodeficiency virus (HIV) lentiviral packaging system and RVFV structural proteins to successfully construct RVFV pseudoviruses. Electron microscopy observation and western blotting indicated that the size, structure, and shape of the packaged pseudoviruses were notably similar to those of HIV lentiviral vectors. Infection inhibition assay results showed that an antibody against RVFV inhibited the infective ability of the RVFV pseudoviruses, and an antibody neutralization assay for RVFV detection was then established. This study has successfully established a neutralization assay based on RVFV pseudoviruses and demonstrated that this method can be used to effectively evaluate antibody neutralization.

An Alternative Inactivant for Rift Valley Fever Virus using Cobra Venom-derived L-Amino Oxidase, which is Related to its Immune Potential

ABSTRACT Vaccine improvement depends on the formulation, adjuvant type and inactivant used. The type of formulation may interfere with immunogenicity. The present work aimed to evaluate the inactivation activity and related immune potential of the Cobra venom-derived LAO enzyme compared to the currently used inactivants (BPL and formalin) for both animal and human vaccines. The RVF virus was completely inactivated within 6 hrs, 4 hrs and 2 hrs after treatment with Formalin, LAO and BPL, respectively. The vaccine potency [ED50] was arranged in a descending order from formalin (0.016) to BPL (0.005) and LAO (0.002). The total IgG levels, Neutralizing Index (NI) and Interferon levels were significantly increased compared to those detected after immunization with the BPL- and Formalin-inactivated vaccine candidates.

Emerging Rift Valley fever in China: What should be known?

Rift Valley fever is an important viral infection that is rarely reported in Asia. The recent emergence of this infection in China is a big global interest. In this short article, the author reviewed and presented important information on this disease.

Efficacy of seed extracts of Annona squamosa and Annona muricata (Annonaceae) for the control of Aedes albopictus and Culex quinquefasciatus (Culicidae)

Objective: To evaluate the potential efficacy of seed extracts of Annona squamosa and Annona muricata used as natural insecticides to control adult and larvae of the vectors Aedes albopictus and Culex quinquefasciatus under laboratory conditions. Methods:Aqueous and oil extracts of the two plants were prepared from dried seeds. Preliminary identifications of the chemical components of each seed extracts were performed using micro-reactional and GCP techniques. Larvae and adults of Aedes albopictus and Culex quinquefasciatus were collected from the breeding sites in coastal and highlands regions of Madagascar. WHO standardized tests of susceptibility for larvae and imaginal stage of mosquitoes were realized to determine mortality and LC50 of mosquitoes. Results: Chemical identifications showed that these extracts contain alkaloids and flavonoids compounds that probably confer their biological insecticidal proprieties. CPG analysis showed also the presence of various fatty acids. On adult mosquitoes, significant insecticidal effects were observed with both aqueous and oil extracts of the two plant seeds compared to mortality induced by deltamethrin, an insecticide used as reference. Extracts of Annona muricata induced high mortality rate to both species of mosquito compared to extracts of Annona squamosa at all concentrations tested. The LC50 of seed extracts ranged from 1% to 5% for adults and 0.5% to 1% for larvae. Conclusions: The seed extracts of these two plants may be used as mosquito controlling agents and offer a new approach to a less costly, practical and environmentally friendly control of vector borne diseases.

Efficacy of seed extracts of Annona squamosa and Annona muricata (Annonaceae) for the control of Aedes albopictus and Culex quinquefasciatus (Culicidae)

Objective: To evaluate the potential efficacy of seed extracts of Annona squamosa and Annona muricata used as natural insecticides to control adult and larvae of the vectors Aedes albopictus and Culex quinquefasciatus under laboratory conditions. Methods: Aqueous and oil extracts of the two plants were prepared from dried seeds. Preliminary identifications of the chemical components of each seed extracts were performed using micro-reactional and GCP techniques. Larvae and adults of Aedes albopictus and Culex quinquefasciatus were collected from the breeding sites in coastal and highlands regions of Madagascar. WHO standardized tests of susceptibility for larvae and imaginal stage of mosquitoes were realized to determine mortality and LC50 of mosquitoes. Results: Chemical identifications showed that these extracts contain alkaloids and flavonoids compounds that probably confer their biological insecticidal proprieties. CPG analysis showed also the presence of various fatty acids. On adult mosquitoes, significant insecticidal effects were observed with both aqueous and oil extracts of the two plant seeds compared to mortality induced by deltamethrin, an insecticide used as reference. Extracts of Annona muricata induced high mortality rate to both species of mosquito compared to extracts of Annona squamosa at all concentrations tested. The LC50 of seed extracts ranged from 1% to 5% for adults and 0.5% to 1% for larvae. Conclusions: The seed extracts of these two plants may be used as mosquito controlling agents and offer a new approach to a less costly, practical and environmentally friendly control of vector borne diseases.