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Lassa fever is an acute and highly contagious international infectious disease. It is an acute infectious disease caused by the Lassa virus, mainly transmitted by rodents, and mainly prevalent in West African countries such as Nigeria, Libya, Sierra Leone, and Guinea. Lassa virus is a member of the family and genus of sand viruses, generally associated with chronic infections in rodent hosts. Lassa virus is a polymorphic two segment ribonucleic acid (RNA) virus with an envelope, sensitive to lipid
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Figure 1. Comparison of the responses induced in vitro by LASV (a) and MOPV (b) in human cells.( Russier, Marion,2012)
Lassa fever is characterized by multiple symptoms, usually with several key manifestations observed, especially in the early stages of infection (as shown in the figure):
Figure 2. Lassa fever of symptoms.
Although these symptoms represent the core early features of Lassa fever, in some cases, the disease may develop into more severe complications such as bleeding, shock, or multiple organ dysfunction. This highlights the importance of early detection and timely medical intervention.
During the invasion phase, LFV utilizes surface glycoproteins (GPC) as its core viral target, first binding to the host cell surface's alpha dystrophin polysaccharide (α - Dystromlycan, α - DG) (the main receptor widely expressed in vascular endothelial cells, macrophages, and renal tubular epithelial cells). In the immune escape process, the NP of LFV can directly bind to the host retinoic acid-induced gene I (RIG-I) (innate immune recognition target), blocking its recognition of viral RNA and inhibiting the production of type I interferon (IFN - α/β). At the same time, the virus Z protein (matrix protein) will degrade the host signal transduction and transcriptional activation factor 1 (STAT1) through the ubiquitination pathway, blocking the downstream signaling pathway of IFN and preventing the host from initiating antiviral immune response; During the pathological injury stage, infected macrophages secrete a large amount of tumor necrosis factor alpha (TNF - α) and interleukin-6 (IL-6), which bind to the TNFR1/TNFR2 (TNF - α receptor) and IL-6R (IL-6 receptor) on the surface of host cells, respectively, activating the inflammatory signaling pathway, leading to activation of endothelial cells, disruption of tight junctions, increased vascular permeability, and systemic bleeding (such as gastrointestinal bleeding and nosebleeds).
The incubation period of Lassa fever is 6-21 days. The onset is slow, and symptoms include general discomfort, fever, sore throat, cough, nausea, vomiting, diarrhea, muscle pain, and chest and abdominal pain. Fever is characterized by persistent or relaxed fever, and inflammation and exudation of the eyes and conjunctiva are common. The vast majority of human infections manifest as mild or asymptomatic, while others manifest as severe multi system diseases. Diseases are particularly severe during pregnancy, and the vast majority of pregnant women may experience miscarriage. Severe cases often result in hypotension or shock, pleural effusion, bleeding, epileptic seizures, encephalopathy, facial disease, and neck edema, often accompanied by proteinuria and blood concentration.
Due to the lack of specific manifestations of Lassa fever, diagnosis is difficult.
1. Patients with fever, purulent pharyngitis, and proteinuria are more likely to develop Lassa fever.
2. Isolation of Lassa virus, with a 4-fold increase in Lassa virus antibodies, positive IgM antibodies. Any positive result can confirm the diagnosis.
1. Symptomatic Supportive Treatment
Rest in bed, maintain water and electrolyte balance, replenish blood volume, prevent and treat shock, closely monitor heart and lung function, monitor blood pressure and kidney function, and use antibiotics when secondary bacterial infections occur.
2. Antiviral Therapy
Ribavirin can be used during the fever period and should be applied as early as possible. Treatment within one week of the disease can reduce mortality. Preferred intravenous administration. Children should be given medication according to their weight, the same as adults.
3. Pregnancy
When Lassa fever infects pregnant women in the late stages of pregnancy, inducing childbirth is necessary for the mother to have a good chance of survival. This is because the virus has an affinity for the placenta and other highly vascular tissues. No matter what action is taken, the fetus has only one in ten chances of survival. Therefore, the focus has always been on saving the mother's life.
Recombinant Lassa Fever Virus (LASV) VLP Antigens are artificially synthesized antigenic substances constructed through genetic engineering technology. They are formed by the self-assembly of key structural proteins of LASV in appropriate host systems, and do not contain the viral genome. As LASV itself is a polymorphic, enveloped two-segment RNA virus (as noted in the original document), these VLP Antigens retain the morphological structure and core antigenic epitopes similar to natural LASV, while lacking replication ability and infectivity—ensuring high biological safety while maintaining strong antigenicity. The core biological characteristics of recombinant lassa fever virus (lasv) vlp antigens is as following:
| Core biological characteristics | Details |
| Strong Antigenicity | By simulating the spatial structure of natural LASV, recombinant LASV VLP antigens can effectively recognize and bind to B and T cells in the host immune system, inducing the production of specific anti LASV antibodies (including IgM and IgG, especially neutralizing antibodies that can block viral infection). |
| High Specificity | Based on the conserved or lineage specific sequence design of LASV structural proteins, these antigens only react specifically with antibodies (or immune cells targeting LASV) against LASV. This avoids cross reactivity with other viruses or unrelated pathogens in the sand particle virus family, which is crucial for improving the accuracy of Lassa fever diagnosis. |
| Excellent Security | Due to the absence of viral genome, recombinant LASV VLP antigens cannot replicate or cause infection in host cells. This eliminates safety risks such as "virulence reversal" that may exist in traditional inactivated or attenuated viral antigens, making it suitable for sensitive scenarios. |
About 15-20% of hospitalized patients with Lassa fever will die from the disease. The overall mortality rate is estimated to be 1%, but during epidemics, the mortality rate may reach as high as 50%. The mortality rate of pregnant women in late pregnancy exceeds 80%. Almost all of these cases will result in fetal death. Some survivors may experience the lasting effects of this disease, which may include partial or complete deafness. Due to treatment with ribavirin, the mortality rate has decreased. Due to treatment with ribavirin and human anti-Lassa virus glycoprotein monoclonal antibody, the mortality rate has decreased.
Controlling the number of Mastomys rodents is unrealistic, so the focus of measures is to keep rodents away from homes and food supplies, encourage effective personal hygiene, store food and other food in rodent proof containers, and dispose of garbage in places far from homes to help maintain a clean home. It is recommended to wear gloves, masks, laboratory coats, and goggles when in contact with infected individuals to avoid contact with blood and bodily fluids. Many countries monitor these issues through public health departments. In underdeveloped countries, such organizations may not have the necessary means to effectively control the epidemic.
Reference
| Target | Cat. No. | Product Name | Size | Species | |
| LASV | DAG-WT370 | Recombinant Lassa Fever Virus (LASV) VLP lineage II | 1 mg | / | Inquiry |
| DAG-WT371 | Recombinant Lassa Fever Virus (LASV) VLP lineage III | 1 mg | / | Inquiry | |
| DAG-WT372 | Recombinant Lassa Fever Virus (LASV) VLP lineage IV | 1 mg | / | Inquiry |
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