• Vaccine Name: ML29 L-AttV, rLCMV(IGR/S-S) (Mopiea/Lassa reassortant)
• Target Pathogen: Lassa Fever Virus
• Target Disease: Lassa fever
• Manufacturer: Profectus Biosciences; University of Texas Medical Branch
• Type: Reassortant
• Status: Research
• Host Species for Licensed Use: None
• Antigen: LASV GPC, LASV NP(Salami et al., 2019)
• LASVsSgp1 nucleoprotein gene engineering:
  • Type: Recombinant vector construction
  • Description: ML29 reassortant vaccine expressing the GP and NP of LASV and the Z and L proteins of Mopeia virus (MOPV) (Zapata et al., 2013).
  • Detailed Gene Information: Click Here.
• LASVsSgp2 glycoprotein gene engineering:
  • Type: Recombinant vector construction
  • Description: ML29 reassortant vaccine expressing the GP and NP of LASV and the Z and L proteins of Mopeia virus (MOPV) (Zapata et al., 2013)
  • Detailed Gene Information: Click Here.
• Preparation: The Mopeia/Lassa (ML29) reassortant virus used in this study can be an effective, broadly cross-reactive Lassa vaccine. The large (L) genomic segment of ML29 is derived from the mild MOPV. The S segment of ML29 encodes the NP and GP gene products derived from LASV. ML29 appears to be even more attenuated than its parental MOPV both in vitro and in vivo. (Zapata et al., 2013)
• Immunization Route: Five of the 8 were given ML29 subcuta- neously (s.c.) and 3 were given ML29 intragastrically (i.g.)

Macaque Response

• Vaccination Protocol: Eight macaques were inoculated with an attenuated LASV vaccine ML-29, in order to determine whether they could still elicit LASV- specific immune responses without developing signs of arenavirus disease. Five of the 8 were given ML29 subcutaneously (s.c.) and 3 were given ML29 intragastrically (i.g.). (Zapata et al., 2013)
• Immune Response: SIV-positive animals were classified as slow, median or rapid progressors based on their physical signs and SIV viral loads at set point, i.e. 3 months after infection. Seven of the 8 SIV/ML29 monkeys experienced a drop in SIV titers (median 20%) during the first week after ML29 inoculation, but those titers returned the following week. In both SIV-infected and non-infected controls, showed a decrease in percentage of circulating NK (CD16+) cells a week after vaccination (Figure 5A and B). The CD14+ (monocyte) population showed a modest increase in the SIV-infected group and a marked increase in the control group one week after ML29 vaccination.Anti-LASV IgG antibodies were detected by ELISA from weeks 1 to week 5 and then monthly until the time of death. All animals showed good titers of anti-Lassa IgG except for those 3 given ML29 by the i.g. route. Seven of the 8 SIV-infected vaccines had vigorous ML29-specific cell-mediated immunity by the first week after vaccination.
  
  (Zapata et al., 2013)
• Side Effects: Two rapid-progressors were euthanized on days 34 and 63 and two median progressors were euthanized on days 57 and 105 after ML29 vaccination (Table 1, Figures 2 and 3). The first euthanized animal (SIV/ML- 3) had high SIV loads and wasted appearance prior to ML29 vaccination. This animal developed a barely- detectable ML29 viremia (103 pfu/ml of plasma) 3 weeks after vaccination. (This titer of 103 pfu ML29/ml is still below the >104 pfu/ml considered to be a disease sign related to poor prognosis in LHF). Transient ML29 viremia (80 pfu/ml of plasma) was also detected one week after vaccination in the second euthanized monkey (SIV/ML-1), and in a long-term surviving monkey (SIV/ ML-8 had 20 pfu/ml plasma) 3 weeks after vaccination. (Zapata et al., 2013)
• Challenge Protocol: 93 days after infection with SIVmac251, eleven rhesus macaques were enrolled in this study. (Zapata et al., 2013)