Heterogeneity of the fibre sequence in subgenus C adenoviruses

Adenoviral-Vectored Centralized Consensus Hemagglutinin Vaccine Provides Broad Protection against H2 Influenza a Virus

Several influenza pandemics have occurred in the past century, one of which emerged in 1957 from a zoonotic transmission of H2N2 from an avian reservoir into humans. This pandemic caused 2–4 million deaths and circulated until 1968. Since the disappearance of H2N2 from human populations, there has been waning immunity against H2, and this subtype is not currently incorporated into seasonal vaccines. However, H2 influenza remains a pandemic threat due to consistent circulation in avian reservoirs. Here, we describe a method of pandemic preparedness by creating an adenoviral-vectored centralized consensus vaccine design against human H2 influenza. We also assessed the utility of serotype-switching to enhance the protective immune responses seen with homologous prime-boosting strategies. Immunization with an H2 centralized consensus showed a wide breadth of antibody responses after vaccination, protection against challenge with a divergent human H2 strain, and significantly reduced viral load in the lungs after challenge. Further, serotype switching between two species C adenoviruses enhanced protective antibody titers after heterologous boosting. These data support the notion that an adenoviral-vectored H2 centralized consensus vaccine has the ability to provide broadly cross-reactive immune responses to protect against divergent strains of H2 influenza and prepare for a possible pandemic.

Adenovirus Type 6: Subtle Structural Distinctions from Adenovirus Type 5 Result in Essential Differences in Properties and Perspectives for Gene Therapy

Adenovirus vectors are the most frequently used agents for gene therapy, including oncolytic therapy and vaccine development. It’s hard to overestimate the value of adenoviruses during the COVID-19 pandemic as to date four out of four approved viral vector-based SARS-CoV-2 vaccines are developed on adenovirus platform. The vast majority of adenoviral vectors are based on the most studied human adenovirus type 5 (HAdV-C5), however, its immunogenicity often hampers the clinical translation of HAdV-C5 vectors. The search of less seroprevalent adenovirus types led to another species C adenovirus, Adenovirus type 6 (HAdV-C6). HAdV-C6 possesses high oncolytic efficacy against multiple cancer types and remarkable ability to induce the immune response towards carrying antigens. Being genetically very close to HAdV-C5, HAdV-C6 differs from HAdV-C5 in structure of the most abundant capsid protein, hexon. This leads to the ability of HAdV-C6 to evade the uptake by Kupffer cells as well as to distinct opsonization by immunoglobulins and other blood proteins, influencing the overall biodistribution of HAdV-C6 after systemic administration. This review describes the structural features of HAdV-C6, its interaction with liver cells and blood factors, summarizes the previous experiences using HAdV-C6, and provides the rationale behind the use of HAdV-C6 for vaccine and anticancer drugs developments.

Adenovirus Isolated From a Cat Is Related to Human Adenovirus 1

An adenovirus (AdV) has been isolated from the rectal swab of a domestic cat (Felis catus) and named feline adenovirus (FeAdV) isolate. It replicates and causes cytopathological effects in many human, feline, other mammalian cell lines that have both Coxsackie-adenovirus-receptor and integrins. Its antigens cross-react with anti-human adenovirus antibodies in immunofluorescence and immunocytochemistry assays. Electron microscopy revealed typical extracellular icosahedral particles and pseudo arrays inside cells. Sequence analysis of hexon and fiber genes indicates that this virus might belong to human adenovirus (HAdV) C species and might be a variant of type 1. In the fiber protein, three altered amino acids occur in the shaft; four altered residues are found in the knob region as compared to a European HAdV might be type 1 isolate (strain 1038, D11). One alteration affects amino acid 442 forming an RGS motif in an alanine rich region that might be an alternative way to bind integrins with subsequent internalization. Substitutions in the hexon sequence are silent. As compared to published HAdV sequences, the fiber is related to the original American prototype and recently described Taiwanese HAdV 1 isolates, but the hexon sequences are related to adenovirus isolates from France, Germany, Japan, and Taiwan. Serology carried out on FeAdV infected M426 cells indicates a prevalence of IgG in 80% of domestic cats in Delaware, United States. FeAdV isolate seems to be a recently recognized virus with possible pathogenic effects and, simultaneous human and feline infections are possible. Further molecular and biological characterization of this feline adenovirus isolate, as well as studies on both human and feline epidemiology and pathomechanisms, especially in endangered big cats, are warranted. FeAdV might have further practical advantages. Namely, it could be utilized in both human and feline AIDS research, developed into diagnostic tools, and gene therapy vectors in the near future.

Retinal transduction profiles by high-capacity viral vectors

Retinal gene therapy with adeno-associated viral (AAV) vectors is safe and effective in humans. However, the limited cargo capacity of AAV prevents their use for therapy of those inherited retinopathies (IRs) due to mutations in large (>5kb) genes. Viral vectors derived from Adenovirus (Ad), Lentivirus (LV) and Herpesvirus (HV) can package large DNA sequences but do not target efficiently retinal photoreceptors (PRs) where the majority of genes responsible for IRs are expressed.

Here, we have evaluated the mouse retinal transduction profiles of vectors derived from 16 different Ad serotypes, 7 LV pseudotypes, and from a bovine HV. Most of the vectors tested transduced efficiently the retinal pigment epithelium (RPE). We found that LV-GP64 tends to transduce more PRs than the canonical LV-VSVG albeit this was restricted to a narrow region. We observed more extensive PR transduction with HdAd1, 2 and 5/F35++ than with LV, although none of them outperformed the canonical HdAd5 or matched the extension of PR transduction achieved with AAV2/8.

Pattern of epithelial cell abnormality in Pap smear: A clinicopathological and demographic correlation

BACKGROUND

In the low resource settings of a developing country, a conventional Papanicolaou (Pap) test is the mainstay screening system for cervical cancer. In order to counsel women and to organize a public health system for cervical cancer screening by Pap smear examination, it is imperative to know the pattern of premalignant and malignant lesions. This study was undertaken to find out the prevalence of an abnormal Pap smear, in a tertiary hospital of a developing country, and to carry out a clinicopathological and demographical analysis for establishing the pattern of epithelial cell abnormality in a Pap smear.

MATERIALS AND METHODS

A cross-sectional descriptive study was carried out in a total of 1699 patients who underwent Pap smear examination. The prevalence of epithelial cell abnormality in the Pap smear was calculated in proportions / percentages. Specimen adequacy and reporting was assessed according to the revised Bethesda system.

RESULTS

Among the total of 1699 patients who had their Pap smear done, 139 (8.18%) revealed epithelial cell abnormality. Altogether 26 smears revealed high-grade lesions and malignancy, most of which were found to be in women belonging to the 30 - 39 and ≥ 45 age group. A total of 75 (53.96%) women were in the 20 - 44 age group and 64 (46.04%) were in the ≥ 45 age group. A bimodal age distribution was detected in the epithelial cell abnormality, with the bulk being diagnosed in patients aged 45 or above. Overall one-third of the patients with an abnormal Pap smear result showed healthy cervix in per vaginal examination.

CONCLUSIONS

A raised prevalence of epithelial cell abnormality reflects the lack of awareness about cervical cancer screening. Women aged 45 or above harbor the bulk of premalignant and malignant lesions in the Pap smear, signifying that these women are among the under users of cytological screening.

Serotype chimeric human adenoviruses for cancer gene therapy

Cancer gene therapy consists of numerous approaches where the common denominator is utilization of vectors for achieving therapeutic effect. A particularly potent embodiment of the approach is virotherapy, in which the replication potential of an oncolytic virus is directed towards tumor cells to cause lysis, while normal cells are spared. Importantly, the therapeutic effect of the initial viral load is amplified through viral replication cycles and production of progeny virions. All cancer gene therapy approaches rely on a sufficient level of delivery of the anticancer agent into target cells. Thus, enhancement of delivery to target cells, and reduction of delivery to non-target cells, in an approach called transductional targeting, is attractive. Both genetic and non-genetic retargeting strategies have been utilized. However, in the context of oncolytic viruses, it is beneficial to have the specific modification included in progeny virions and hence genetic modification may be preferable. Serotype chimerism utilizes serotype specific differences in receptor usage, liver tropism and seroprevalence in order to gain enhanced infection of target tissue. This review will focus on serotype chimeric adenoviruses for cancer gene therapy applications.

Characterization of human adenovirus serotypes 5, 6, 11, and 35 as anticancer agents

Human adenovirus type 5 (Ad5) has been the most popular platform for the development of oncolytic Ads. Alternative Ad serotypes with low seroprevalence might allow for improved anticancer efficacy in Ad5-immune patients. We studied the safety and efficacy of rare serotypes Ad6, Ad11 and Ad35. In vitro cytotoxicity of the Ads correlated with expression of CAR and CD46 in most but not all cell lines. Among CAR-binding viruses, Ad5 was often more active than Ad6, among CD46-binding viruses Ad35 was generally more cytotoxic than Ad11 in cell culture studies. Ad5, Ad6, and Ad11 demonstrated similar anticancer activity in vivo, whereas Ad35 was not efficacious. Hepatotoxicity developed only in Ad5-injected mice. Predosing with Ad11 and Ad35 did not increase infection of hepatocytes with Ad5-based vector demonstrating different interaction of these Ads with Kupffer cells. Data obtained in this study suggest developing Ad6 and Ad11 as alternative Ads for anticancer treatment.

Evidence of frequent recombination among human adenoviruses

Genome stability is a prerequisite for the production and use of adenoviruses for therapy of genetic diseases and cancer. To test the premise that the adenoviral genome is stable, the phylogenetic relationships of 16 adenovirus C (AdC) field isolates were studied in four genome regions: hexon, fiber, polymerase and E1A. The phylogenetic relationships in the fiber gene concurred with those in the hexon region. In contrast, the non-structural regions had marks of frequent recombination, to the point that an isolate of one serotype could contain non-structural proteins that were identical to the genes from a different serotype. Our results suggest that recombination among circulating adenoviruses is very frequent and plays an important role in shaping the phylogenetic relationships of adenovirus genomes. Analysis of the available complete genome sequences of AdB, AdC and AdD species showed that recombination shuffles genome fragments within a species, but not between species. One of the AdC field isolates possessed the fiber gene of AdC type 6, but a hexon gene that was distinct from all AdC serotypes. This strain could not be typed unambiguously in a neutralization test and might represent a novel serotype of AdC. Comparison of the right end (nt 18838–33452) of this isolate with that of the ATCC Ad6 strain showed clear evidence of multiple recombination events.

Adenovirus type 7 peptide diversity during outbreak, Korea, 1995-2000

To understand the molecular basis of observed regional shifts in the genome types of adenovirus type 7 (Ad7) isolated in Korea during nationwide outbreaks from 1995 to 2000, the genetic variabilities of Ad7d and Ad7l were studied by sequence analysis of hexon, fiber, E3, and E4 open reading frame (ORF) 6/7 peptides. One amino acid change in the receptor-binding domain of fiber and 6 amino acid variations in E4 ORF 6/7 were identified between 2 genome types, while no variations were found in hexon and E3. Phylogenetic trees based on hexon, fiber, and E4 suggested that the Ad7 epidemic was probably caused by the introduction of the Japanese Ad7d strains. Our data also provide evidence that the rapid divergence of Ad7d to a novel genome type Ad7l could have been due to viral strategies involving multiple sequence changes in E4. This result suggests fiber and E4 ORF 6/7 peptides participate in the evolution of Ad7.

Invasive adenoviral infection in a recipient of unrelated bone marrow transplantation: Problems with diagnostic PCR

A hematopoietic stem cell transplantation (SCT) recipient developed severe diarrhea and fever. A rapid test for the presence of adenovirus (AdV)-specific antigen in the patient's stools was positive; however, AdV genome was not detected by conventional or real-time polymerase chain reaction (PCR). AdV was confirmed by specific PCR for AdV serotype 7 and by an AdV hexon/fiber gene DNA sequence homology search of the PCR product. We suspect that conventional/real-time PCR failed to detect AdV due to nine silent single base substitutions in the extracted AdV genome. Treatment with 1 mg/kg cidofovir (CDV) intravenously three times a week was effective.