Neutralization sensitivity of HIV-1 subtype B' clinical isolates from former plasma donors in China

A defucosylated bispecific multivalent molecule exhibits broad HIV-1-neutralizing activity and enhanced antibody-dependent cellular cytotoxicity against reactivated HIV-1 latently infected cells

OBJECTIVE

Current treatments cannot completely eradicate HIV-1 owing to the presence of latently infected cells, which harbor transcriptionally silent HIV-1. However, defucosylated antibodies can readily kill latently infected cells after their activation to express envelope glycoprotein (Env) through antibody-dependent cellular cytotoxicity (ADCC). We herein aimed to test a defucosylated bispecific multivalent molecule consisting of domain-antibody and single-domain CD4, LSEVh-LS-F, for its HIV-1 neutralizing activity and ADCC against the reactivated latently infected cells, compared with the nondefucosylated molecule LSEVh-LS.

METHODS

LSEVh-LS-F's neutralizing activity against a panel of newly characterized Chinese HIV-1 clinical isolates was assessed by using TZM-bl-based and PBMC-based assays. LSEVh-LS-F-mediated ADCC in the presence of natural killer cells against cell lines that stably express Env proteins, HIV-1-infected cells and LRA-reactivated HIV-1 latent cells, was measured using a lactate dehydrogenase (LDH) cytotoxicity assay or flow cytometry.

RESULTS

LSEVh-LS-F and LSEVh-LS were equally effective in neutralized infection of all HIV-1 isolates tested with IC50 and IC90 values 3∼4-fold lower than those of VRC01. LSEVh-LS-F was more effective in natural killer-mediated killing of HIV-1 Env-expressing cell lines, HIV-1-infected cells, latency reactivation agents-reactivated ACH2 cells and reactivated latently infected resting CD4+ T cell line as well as resting CD4+ T lymphocytes isolated from patients receiving HAART.

CONCLUSION

LSEVh-LS-F exhibits broad HIV-1 neutralizing activity and enhanced ADCC against HIV-1-infected cells, reactivated latently infected cell lines and primary CD4+ T cells, thus being a promising candidate therapeutic for eradicating the HIV-1 reservoir.

Escape from humoral immunity is associated with treatment failure in HIV-1-infected patients receiving long-term antiretroviral therapy

Interindividual heterogeneity in the disease progression of HIV-1-infected patients receiving long-term antiretroviral therapy suggests that some host-related factors may have limited treatment efficacy. To understand the nature of factors contributing to treatment failure, we performed a retrospective cohort study of 45 chronically HIV-1-infected individuals sharing a similar demographics and route of infection, compared the differences between virologically suppressed (VS) and treatment failure (TF) patients with respect to clinical, immunological and virological characteristics. We found that the baseline diversity of HIV-1 env quasispecies was the major difference between VS and TF group, and higher baseline diversity in TF patients. We further predicted TF-related env mutations using a selection pressure-based approach, followed by an analysis of these mutations based on the available three-dimensional structures of gp120/gp41 or their complexes with neutralizing antibodies. Notably, almost all of the identified residues could be mapped to the epitopes of known HIV-1 neutralizing antibodies, especially the epitopes of broadly neutralizing antibodies, and these mutations tended to compromise antibody-antigen interactions. These results indicate that the escape of HIV-1 from host humoral immunity may play a direct role in TF in long-term antiretroviral-experienced patients and that based on env gene sequence of the viruses in the patients.

Profiling the neutralizing antibody response in chronically HIV-1 CRF07_BC-infected intravenous drug users naïve to antiretroviral therapy

Characterizing neutralizing antibody (NAb) responses in individuals infected with diverse HIV-1 strains is necessary to reveal the novel targets for regional preventive and therapeutic strategies development. We evaluated the prevalence, breadth, and potency of NAb responses in 98 CRF07_BC-infected individuals using a large, multi-subtype panel of 30 tier 2-3 Env-pseudotyped viruses. Furthermore, we compared the neutralization pattern of CRF07_BC-infected people with that of subtype B’-infected individuals in China. Of the 98 plasma samples tested, 18% neutralized more than 80% of viruses in the panel, and 53% neutralized more than 50%, suggesting the presence of broadly NAbs in these individuals. A preferential intra-subtype neutralization of CRF07_BC was found. Notably, CRF07_BC-infected individuals generated higher neutralization titers against intra-subtype viruses than subtype B’-infected individuals with longer infection length. However, subtype B’-infected individuals mounted broader neutralization responses against inter-subtype viruses than CRF07_BC infection with shorter infection time, indicating the transition from narrow autologous to broad heterologous neutralization over time. Neutralization activity of the top six plasmas from each cohort was attributable to IgG fraction, and half of them developed CD4 binding site antibody reactivity. Heatmap analysis identified three statistically robust clusters of plasmas that offer valuable resources for further in-depth virological and immunological study.

A phloem-limited fijivirus induces the formation of neoplastic phloem tissues that house virus multiplication in the host plant

A number of phloem-limited viruses induce the development of tumours (enations) in the veins of host plants, but the relevance of tumour induction to the life cycle of those viruses is unclear. In this study, we performed molecular and structural analyses of tumours induced by rice black-streaked dwarf virus (RBSDV, genus Fijivirus) infection in maize plants. The transcript level of the maize cdc2 gene, which regulates the cell cycle, was highly elevated in tumour tissues. Two-dimensional electrophoresis identified 25 cellular proteins with altered accumulation in the tumour tissues. These proteins are involved in various metabolic pathways, including photosynthesis, redox, energy pathways and amino acid synthesis. Histological analysis indicated that the tumours predominantly originated from hyperplastic growth of phloem, but those neoplastic tissues have irregular structures and cell arrangements. Immunodetection assays and electron microscopy observations indicated that in the shoots, RBSDV is confined to phloem and tumour regions and that virus multiplication actively occurs in the tumour tissue, as indicated by the high accumulation of non-structural proteins and formation of viroplasms in the tumour cells. Thus, the induction of tumours by RBSDV infection provides a larger environment that is favourable for virus propagation in the host plant.

Complete genome sequence of the cold-active bacteriophage VMY22 from Bacillus cereus

The cold-active bacteriophage VMY22, belonging to the Podoviridae family, was isolated from Mingyong Glacier in China. Sequence analysis revealed that the genome is 18,609 bp long, with an overall G + C content of 36.4 mol%, and 25 open reading frames (ORFs). The sequence contains 46 potential promoters, 6 transcription terminators, and no tRNAs. Most of the ORFs show a high degree of similarity to B103 (NC_004165). Two noteworthy findings were made. First, one of the predicted proteins, ORF 19, shows high sequence similarity to the bacteriocin biosynthesis protein from Bacillus cereus. From this information, we propose that the VMY22 phage is at an intermediate phase in its coevolution with its bacterial host. Second, seven of the hypothetical proteins appear to be unique to this cold-active B. cereus phage (i.e., not found in temperate-active B. cereus phages). These observations add to our current knowledge about the coevolution of bacteriophages and their hosts. The identification of a novel group of gene and protein structures and functions will lead to a better understanding of cold-adaptation mechanisms in bacteria and their bacteriophages.

Prevalence of rotavirus, norovirus and enterovirus in diarrheal diseases in Himachal Pradesh, India

Diarrheal diseases are responsible for a significant proportion of mortality and morbidity all around the globe. The contribution of viruses to gastroenteritis incidences in humans is well established. In the present study, we have studied the prevalence of rotavirus, norovirus and enterovirus in Himachal Pradesh, a north Indian state. A total of 287 (111 children and 176 adults) stool samples of gastroenteritis patients were screened for the viruses using RT-PCR method. 34.5 % samples were positive for the viral pathogens of gastroenteritis. Rotavirus was the predominant virus detected in the study with 49.5 and 14.8 % positivity in children and adults, respectively. Enterovirus was present in 5.6 % cases whereas norovirus had least prevalence (1.4 %). Co infection (rotavirus and enterovirus) was witnessed at the prevalence rate of 0.6 %. Among different age groups, the prevalence of studied viruses was highest in the children belonging to the age groups of <5 years. Rotavirus infections were found to be significantly associated with vomiting and trend of higher rates of fever and dehydration was seen in children along with diarrhea. Seasonal distribution shows circulation of diarrheagenic viruses throughout the year. This is the first report of prevalence of various diarrheagenic viruses circulating in this region. The outcome of the study from this cohort provides a baseline data which can be used to design the preventive strategies in the otherwise unexplored state of Himachal Pradesh.

Genotypes of hepatitis C virus in relapsed and non-respondent patients and their response to anti-viral therapy in district Mardan, Khyber Pakhtunkhawa, Pakistan

Hepatitis C is a blood-borne infectious disease of liver, caused by a small enveloped, positive-single stranded RNA virus, called the hepatitis C virus (HCV). HCV belongs to the Flaviviridae family and has 6 genotypes and more than 100 subtypes. It is estimated that 185 million people are infected with HCV worldwide and 5% of these are in Pakistan. The study was designed to evaluate different genotypes of HCV circulating in District Mardan and to know about the behavior of these genotypes to different anti-viral regimes. In this study 3,800 patients were exposed to interferon alfa-2a plus Ribavirin treatment for 6-months and subjected to real-time PCR to check the viral response. Among these 3,677 (97%) patients showed no detectable HCV RNA while 123 (3%) patients (non-responders) remained positive for HCV RNA. Genotypes of their analyzed showed that most of them belonged to the 3a genotype. Non-responders (123) and relapsed (5) patients were subjected to PEG-interferon and Ribavirin therapy for next 6 months, which resulted into elimination of HCV RNA from 110 patients. The genotypes of the persisting resistant samples to anti-viral treatment were 3b, 2a, 1a and 1b. Furthermore, viral RNA from 6 patients remained un-typed while 4 patients showed mixed infections. HCV was found more resistant to antiviral therapy in females as compared to mals. The age group 36-45 in both females and males was found most affected by infection. In general 3a is the most prevalent genotype circulating in district Mardan and the best anti-viral therapy is PEG-interferon plus Ribavirin but it is common practice that due to the high cost patients receive interferon alfa-2a plus Ribavirin with consequent resistance in 3% patients given this treatment regime.