The development of HIV vaccines targeting gp41 membrane-proximal external region (MPER): challenges and prospects

A human immunodeficiency virus type-1 (HIV-1) vaccine which is able to effectively prevent infection would be the most powerful method of extinguishing pandemic of the acquired immunodeficiency syndrome (AIDS). Yet, achieving such vaccine remains great challenges. The membrane-proximal external region (MPER) is a highly conserved region of the envelope glycoprotein (Env) gp41 subunit near the viral envelope surface, and it plays a key role in membrane fusion. It is also the target of some reported broadly neutralizing antibodies (bNAbs). Thus, MPER is deemed to be one of the most attractive vaccine targets. However, no one can induce these bNAbs by immunization with immunogens containing the MPER sequence(s). The few attempts at developing a vaccine have only resulted in the induction of neutralizing antibodies with quite low potency and limited breadth. Thus far, vaccine failure can be attributed to various characteristics of MPER, such as those involving structure and immunology; therefore, we will focus on these and review the recent progress in the field from the following perspectives: (1) MPER structure and its role in membrane fusion, (2) the epitopes and neutralization mechanisms of MPER-specific bNAbs, as well as the limitations in eliciting neutralizing antibodies, and (3) different strategies for MPER vaccine design and current harvests.

Origin and Phylogenetic Characteristics of Dengue Virus Isolated from the Large Outbreak of Dengue in Guangdong Province in 2014 / 中山大学学报(医学科学版)

[Objects]To isolate and identify the pathogen of the large outbreak of dengue in Guangdong province in 2014. To understand the origin and the phylogenetic characteristics of the isolates ,and provide scientific foundation for the surveillance and prevention of dengue fever.[Methods]Collected the patient serum samples over all the Guangdong province during the 2014 outbreakperiod,isolated and identified the virus from these samples. Amplified complete E gene and complete genome with certain primers and sequenced all the products. Then the Phylogenetic ,Bayesian phylogeography and mutations analysis were carried.[Results]40 DENV-1 strains were isolated and identified. 40 complete E gene sequences and 6 complete genome sequences of DENV-1 were obtained. Phylogenetic analysis with E gene sequences revealed that the 40 isolates were classified into two genotypes including 16 genotypeⅠ(Asia)and 24 genotypeⅤ(America/Africa). 14 genotypeⅠisolates were clustered closest with isolates from Guangdong province(2013)and Sigapore(2013)which share the nucletide identities of 99.6% ~ 99.9%,other two genotypeⅠisolates were clustered with strains from Malaysia (2013) and both share the nucletide identities of 99.7%;24 genotypeⅤisolates were all classified in one clade with striains from Bangladesh(2009),China(2009)and Bhutan(2013)which share nucletide identities of 99.0%-99.9%. Further analysis with six complete genome sequences showed that five isolates were clustered closest with strains isolated from Guangdong province(2013)share the nucletide identities of 99.6%-99.8% while the sixth stains closest with strains isolated from Myanmar(2002)share the nucletide identities of 98.8%. The isolates have five amino acid mutations compared with strains epidemic in Guangdong province in 2013,three mutations(S88V,E203G,T275R)are in the EⅡdomain and one mutation (S305P)is in the EⅢdomain which associated with virulence.[Conclusions]During the outbreak in Guangdong province in 2014, DENV-1 is the predominant causative serotype,and there are at least two different kinds of genotypes of DENV-1 largely epidemiced in the whole province. Evolution analysis reveals the multiple origins of the isolates which may origin from Guangdong province , Sigapore,Malaysia,Myanmar so that we should enhance the study and surveillance of autochthonous and vectors in order to understand the epidemic way of dengue in Guangdong province. The isolates have had four mutations in the domain associated with virulence which remain further study to know their biological effects.