High level serum neutralizing antibody against HIV-1 in Chinese long-term non-progressors

Invasive Haemophilus influenzae disease among adults in Japan during 2014-2018

PURPOSE

We describe the epidemiology of invasive Haemophilus influenzae disease (IHD) among adults in Japan.

METHODS

Data for 200 adult IHD patients in 2014-2018 were analyzed. The capsular type of H. influenzae was determined by bacterial agglutination and polymerase chain reaction (PCR), and non-typeable Haemophilus influenzae (NTHi) was identified by PCR.

RESULTS

The annual incidence of IHD (cases per 100,000 population) was 0.12 for age 15-64 years and 0.88 for age ≥ 65 years in 2018. The median age was 77 years, and 73.5% were aged ≥ 65 years. About one-fourth of patients were associated with immunocompromising condition. The major presentations were pneumonia, followed by bacteremia, meningitis and other than pneumonia or meningitis (other diseases). The case fatality rate (CFR) was 21.2% for all cases, and was significantly higher in the ≥ 65-year group (26.1%) than in the 15-64-year group (7.5%) (p = 0.013). The percentage of cases with pneumonia was significantly higher in the ≥ 65-year group than in the 15-64-year group (p < 0.001). The percentage of cases with bacteremia was significantly higher in the 15-64-year group than in the ≥ 65-year group (p = 0.027). Of 200 isolates, 190 (95.0%) were NTHi strains, and the other strains were encapsulated strains. 71 (35.5%) were resistant to ampicillin, but all were susceptible to ceftriaxone.

CONCLUSION

The clinical presentations of adult IHD patients varied widely; about three-fourths of patients were age ≥ 65 years and their CFR was high. Our findings support preventing strategies for IHD among older adults, including the development of NTHi vaccine.

Broadly Neutralizing Antibody Responses in a Subset of HIV-1-Infected Individuals in Chennai, India

Identification of broadly neutralizing antibodies (NAbs) generated during the course of HIV-1 infection is essential for effective HIV-1 vaccine design. The magnitude and breadth of neutralizing activity in the sera from 46 antiretroviral treatment-naive HIV-1 clade C-infected individuals was measured in a single round infection assay using TZM-bl cells and multisubtype panel of env-pseudotyped viruses. Higher levels of NAb response (NAb titer 500 to >40 000) were measured in these patients against tier 1 and tier 2 viruses. The average magnitude of the NAb responses of chronically infected individuals against heterologous viruses was consistently higher than the response observed from individuals with long-term nonprogressor ( P = .086). To conclude, high titers of HIV-1 cross-neutralizing activity were observed in the sera from a subset of HIV-1-infected individuals in Chennai, India. Additional studies of the epitopes recognized by these antibodies may facilitate the discovery of an effective vaccine immunogen.

Design and characterization of a peptide mimotope of the HIV-1 gp120 bridging sheet

The Bridging Sheet domain of HIV-1 gp120 is highly conserved among the HIV-1 strains and allows HIV-1 binding to host cells via the HIV-1 coreceptors. Further, the bridging sheet domain is a major target to neutralize HIV-1 infection. We rationally designed four linear peptide epitopes that mimic the three-dimensional structure of bridging sheet by using molecular modeling. Chemically synthesized peptides BS3 and BS4 showed a fair degree of antigenicity when tested in ELISA with IgG purified from HIV(+) broadly neutralizing sera while the production of synthetic peptides BS1 and BS2 failed due to their high degree of hydrophobicity. To overcome this limitation, we linked all four BS peptides to the COOH-terminus of GST protein to test both their antigenicity and immunogenicity. Only the BS1 peptide showed good antigenicity; however, no envelope specific antibodies were elicited upon mice immunization. Therefore we performed further analyses by linking BS1 peptide to the NH2-terminus of the E2 scaffold from the Geobacillus Stearothermophylus PDH complex. The E2-BS1 fusion peptide showed good antigenic results, however only one immunized rabbit elicited good antibody titers towards both the monomeric and oligomeric viral envelope glycoprotein (Env). In addition, moderate neutralizing antibodies response was elicited against two HIV-1 clade B and one clade C primary isolates. These preliminary data validate the peptide mimotope approach as a promising tool to obtain an effective HIV-1 vaccine.

Immunogenicity and safety of 10-valent pneumococcal non-typeable Haemophilus influenzae protein D-conjugate vaccine (PHiD-CV) co-administered with routine childhood vaccines in Taiwan

BACKGROUND/PURPOSE

The immunogenicity and safety of the 10-valent pneumococcal nontypeable Haemophilus influenzae (H. Influenzae) protein D conjugate vaccine (PHiD-CV), co-administered with routine childhood vaccines, were assessed in Taiwanese infants.

METHODS

In this open study, 230 healthy infants were primed with three doses of PHiD-CV (Synflorix) and diphtheria, tetanus, acellular pertussis, hepatitis B (HBV), inactivated poliomyelitis and Haemophilus influenzae type b (Hib) conjugate vaccine (DTPa-HBV-IPV/Hib vaccine) at 1.5, 3 and 6 months of age and two doses of oral human rotavirus vaccine at 1.5 and 3 months. Pneumococcal immune responses were assessed 1 month post-dose three, by 22F-inhibition ELISA and opsonophagocytic activity (OPA) assay. Local and general solicited/unsolicited symptoms and serious adverse events (SAEs) were recorded.

RESULTS

At least 95.4% of participants had an antibody concentration ≥ 0.2 μg/mL against each vaccine serotype. At least 96.1% of participants had an OPA titer ≥ 8 against each vaccine serotype except 6B (87.3%). All infants, but one, were seropositive for antibodies against nontypeable H. influenzae protein D. Immune responses to the co-administered vaccines were good and in line with previous reports. PHiD-CV was well tolerated, with low (≤ 6.3%) incidences of grade 3 solicited local symptoms. The frequencies of general symptoms were in line with other pneumococcal conjugate vaccine studies. There were no systematic increases in incidences of solicited general or local symptoms with successive doses. There were no reports of grade 3 fever (rectal temperature > 40 °C) or SAEs considered to be causally related to vaccination.

CONCLUSION

PHiD-CV co-administered with routine childhood vaccines within the first 6 months of life, was highly immunogenic, and well tolerated in Taiwanese infants.

Epidemiological and microbiological characteristics of culture-proven acute otitis media in Taiwanese children

BACKGROUND/PURPOSE

Acute otitis media (AOM) is one of the most common diseases in children. Here, we describe the epidemiological and microbiological characteristics of AOM in Taiwanese children over a 10-year period.

METHODS

We retrospectively enrolled pediatric patients with culture-proven AOM who were treated at Mackay Memorial Hospital, Taipei between 1999-2008. The data include demographic characteristics, clinical history, and microbiological characteristics.

RESULTS

Six hundred and fourteen patients were included. The male:female ratio was 1.4 (p<0.001). Greater than three-fourths of the patients (476 [77.5%]) were < 5 years of age, and most patients were 1-2 years of age. The most common isolated pathogen was Streptococcus pneumoniae (419 patients [68.2%]), followed by nontypeable Haemophilus influenzae (NTHi; 118 patients [19.2%]). The distributions of age, gender, use of tympanocentesis, history of previous AOM, and use of antibiotic between patients infected with the two pathogens were not significantly different. However, the number of patients with AOM caused by S. pneumoniae, but not NTHi, decreased during the study period (p=0.004). Three hundred and eighty-seven children (63.0%) with AOM developed spontaneous otorrhea. Compared with patients who underwent tympanocentesis, those with spontaneous otorrhea were younger (27.0±16.4 vs. 31.1±15.2 months of age, p=0.004), more likely to have a previous history of AOM (p=0.019), and more likely to receive more antibiotics (p=0.012). The third most common pathogen was S. pyogenes (25 patients [4.1%]). S. pyogenes occurred more often in children > 5 years of age and was associated with spontaneous otorrhea (p<0.001).

CONCLUSION

S. pneumoniae and NTHi are common causes of culture-confirmed AOM in Taiwanese children. Although S. pyogenes is not as common, it usually causes AOM in children > 5 years of age and is associated with spontaneous otorrhea.

Loss of memory B cells during chronic HIV infection is driven by Foxo3a- and TRAIL-mediated apoptosis

Loss of memory B cells occurs from the onset of HIV-1 infection and persists into the chronic stages of infection. Lack of survival of these cells, even in subjects being treated, could primarily be the consequence of an altered local microenvironment induced by HIV infection. In this study we showed that memory B cell survival was significantly decreased in aviremic successfully treated (ST) subjects compared with subjects who control viral load as a result of natural immunity (elite controller [EC]) or with uninfected control (HIV-) subjects. The lower survival levels observed in memory B cells from ST subjects were the result of disrupted IL-2 signaling that led to increased transcriptional activity of Foxo3a and increased expression of its proapoptotic target TRAIL. Notably, memory B cell survival in ST subjects was significantly enhanced by the addition of exogenous IL-2 in a Foxo3a-dependent manner. We further showed that Foxo3a silencing by siRNA resulted in decreased expression of TRAIL and apoptosis levels in memory B cells from ST subjects. Our results thus establish a direct role for Foxo3a/TRAIL signaling in the persistence of memory B cells and provide a mechanism for the reduced survival of memory B cells during HIV infection. This knowledge could be exploited for the development of therapeutic and preventative HIV vaccines.

Broadly cross-neutralizing antibodies in HIV-1 patients with undetectable viremia

Several recent studies have identified HIV-infected patients able to produce a broad neutralizing response, and the detailed analyses of their sera have provided valuable information to improve future vaccine design. All these studies have excluded patients on antiretroviral treatment and with undetectable viral loads, who have an improved B cell profile compared to untreated patients. To better understand the induction of neutralizing antibodies in patients on antiretroviral treatment with undetectable viremia, we have screened 508 serum samples from 364 patients (173 treated and 191 untreated) for a broadly neutralizing antibody (bNAb) response using a new strategy based on the use of recombinant viruses. Sera able to neutralize a minipanel of 6 recombinant viruses, including envelopes from 5 different subtypes, were found in both groups. After IgG purification, we were able to confirm the presence of IgG-associated broadly neutralizing activity in 3.7% (7 of 191) of untreated patients with detectable viremia and 1.7% (3 of 174) of aviremic patients receiving antiretroviral treatment. We thus confirm the possibility of induction of a broad IgG-associated neutralizing response in patients on antiretroviral treatment, despite having undetectable viremia. This observation is in stark contrast to the data obtained from long-term nonprogressors, whose little neutralizing activity has been attributed to the low levels of viral replication.

Applying bioinformatics for antibody epitope prediction using affinity-selected mimotopes - relevance for vaccine design

To properly characterize protective polyclonal antibody responses, it is necessary to examine epitope specificity. Most antibody epitopes are conformational in nature and, thus, cannot be identified using synthetic linear peptides. Cyclic peptides can function as mimetics of conformational epitopes (termed mimotopes), thereby providing targets, which can be selected by immunoaffinity purification. However, the management of large collections of random cyclic peptides is cumbersome. Filamentous bacteriophage provides a useful scaffold for the expression of random peptides (termed phage display) facilitating both the production and manipulation of complex peptide libraries. Immunoaffinity selection of phage displaying random cyclic peptides is an effective strategy for isolating mimotopes with specificity for a given antiserum. Further epitope prediction based on mimotope sequence is not trivial since mimotopes generally display only small homologies with the target protein. Large numbers of unique mimotopes are required to provide sufficient sequence coverage to elucidate the target epitope. We have developed a method based on pattern recognition theory to deal with the complexity of large collections of conformational mimotopes. The analysis consists of two phases: 1) The learning phase where a large collection of epitope-specific mimotopes is analyzed to identify epitope specific “signs” and 2) The identification phase where immunoaffinity-selected mimotopes are interrogated for the presence of the epitope specific “signs” and assigned to specific epitopes. We are currently using computational methods to define epitope “signs” without the need for prior knowledge of specific mimotopes. This technology provides an important tool for characterizing the breadth of antibody specificities within polyclonal antisera.