In conclusion, the results of this study show that health care workers also face a number of barriers in their efforts to provide good PMTCT services at different levels of the health services in Hanoi. These include a high workload, a lack of equipment and materials, lack of training and skills updating, the common fear of the type of patients who may present with HIV, and little support to improve their performance. These weak points can be addressed by a number of feasible interventions. Results of the study contribute to the picture of the PMTCT programme not only in low-prevalence settings, as in Asian countries, but also in high-prevalence settings with weak health care systems, such as African countries, and may require different interventions to improve the quality of the service. Inhibition of Lassa Virus Glycoprotein Cleavage and Multicycle Replication by Site 1 Protease-Adapted α(1)-Antitrypsin Variants BACKGROUND: Proteolytic processing of the Lassa virus envelope glycoprotein precursor GP-C by the host proprotein convertase site 1 protease (S1P) is a prerequisite for the incorporation of the subunits GP-1 and GP-2 into viral particles and, hence, essential for infectivity and virus spread. Therefore, we tested in this study the concept of using S1P as a target to block efficient virus replication. METHODOLOGY/PRINCIPAL FINDING: We demonstrate that stable cell lines inducibly expressing S1P-adapted α(1)-antitrypsin variants inhibit the proteolytic maturation of GP-C. Introduction of the S1P recognition motifs RRIL and RRLL into the reactive center loop of α(1)-antitrypsin resulted in abrogation of GP-C processing by endogenous S1P to a similar level observed in S1P-deficient cells. Moreover, S1P-specific α(1)-antitrypsins significantly inhibited replication and spread of a replication-competent recombinant vesicular stomatitis virus expressing the Lassa virus glycoprotein GP as well as authentic Lassa virus. Inhibition of viral replication correlated with the ability of the different α(1)-antitrypsin variants to inhibit the processing of the Lassa virus glycoprotein precursor. CONCLUSIONS/SIGNIFICANCE: Our data suggest that glycoprotein cleavage by S1P is a promising target for the development of novel anti-arenaviral strategies. Lassa virus (LASV) belongs to the family Arenaviridae, which are enveloped, single-stranded RNA viruses distributed worldwide. Based on their antigenic relationships and geographic distribution, arenaviruses are divided into two major groups. The Old World group includes the prototype of this family, lymphocytic choriomeningitis virus (LCMV), and LASV, which is endemic in West African countries and causes every year thousands of human infections with hemorrhagic fever as a severe clinical manifestation [1] . The New World group includes among others Machupo, Junin, Guanarito and Sabia viruses which can cause viral hemorrhagic fever (VHF). With the exception of the New World virus Tacaribe, which was isolated from Artibeus bats, arenaviruses are rodent-borne viruses [2] .