Characterization of a new insect cell line that is derived from the neonate larvae of Papilio xuthus (Lepidoptera: Papilionidae) and its susceptibility to AcNPV

Effects of hTERT transfection on the telomere and telomerase of Periplaneta americana cells in vitro

Telomere and telomerase are crucial factors in cell division and chromosome stability. Telomerase activity in most cells depends on the transcription control by the telomerase reverse transcriptase (TERT). The introduction of an exogenous human TERT (hTERT) in cultured cells could enhance telomerase activity and elongate the lifespan of various cells. Telomere elongation mechanisms vary between insects and are complex and unusual. Whether the use of exogenous hTERT can immortalize primary insect cells remains to be investigated. In this study, we used a recombinant virus expressing hTERT to infect primary cultured cells of Periplaneta americana and evaluated its effects on insect cell immortalization. We found that hTERT was successfully expressed and promoted the growth of P. americana cells, shortening their doubling time. This was due to the ability of hTERT to increase the activity of telomerase in P. americana cells, thus prolonging the telomeres. Our study lays the foundation for understanding the mechanisms of telomere elongation in P. americana, and suggests that the introduction of hTERT into insect cells could be an efficient way to establish certain insect cell lines.

A database of crop pest cell lines

We have developed an online database describing the known cell lines from Coleoptera, Diptera, Hemiptera, Hymenoptera, and Lepidoptera that were developed from agricultural pests. Cell line information has been primarily obtained from previous compilations of insect cell lines. We conducted in-depth Internet literature searches and drew on Internet sources such as the Cellosaurus database (https://web.expasy.org/cellosaurus/), and inventories from cell line depositories. Here, we report on a new database of insect cell lines, which covers 719 cell lines from 86 species. We have not included cell lines developed from Drosophila because they are already known from published databases, such as https://dgrc.bio.indiana.edu/cells/Catalog. We provide the designation, tissue and species of origin, cell line developer, unique characteristics, its use in various applications, publications, and patents, and, when known, insect virus susceptibility. This information has been assembled and organized into a searchable database available at the link https://entomology.ca.uky.edu/aginsectcellsdatabase which will be updated on an ongoing basis.

Study of the heterologous gene expression characteristics of a new clone of a cell line derived from Papilio xuthus and its serum-free adaptation

The baculovirus expression vector system using insect cells as a bioreactor has been used for in vitro expression of recombinant proteins and plays an important role in the fields of biology, agronomy, and medicine. Screening suitable host cell lines is an important part of the construction of insect cell baculovirus expression systems. In previous research, we used a single-cell cloning process with the Papilio xuthus cell line RIRI-PX1 and obtained the monoclonal cell line RIRI-PX1-C31. In this study, we compared the basic biological and recombinant protein expression characteristics of RIRI-PX1-C31 and its parent cell line RIRI-PX1 and found that the expression of recombinant β-galactosidase in RIRI-PX1-C31 was significantly higher than that in the parental cell line. Further serum-free adaptation studies confirmed that RIRI-PX1-C31 can adapt to the growth environment of Express Five Serum-free medium and that its expression level of recombinant β-galactosidase was significantly higher than that before adaptation.

An embryonic cell line from the American cockroach Periplaneta americana L. (Blattaria: Blattidae) exhibits susceptibility to AcMNPV

Although the baculovirus expression vector system (BEVS) is widely used in the production of recombinant proteins, only a few lepidopteran insect cell lines have been successfully used so far. This study aimed at evaluating the characteristics of an embryonic cell line from the American cockroach Periplaneta americana L., RIRI-PA1, and determining whether it could be used in recombinant protein expression. Wild type Autographa californica multiple nucleopolyhedrovirus (AcMNPV-wt) and green fluorescent protein (GFP)-replicating recombinant baculoviruses (AcMNPV-GFP) were used to infect RIRI-PA1 respectively, demonstrating that RIRI-PA1 cells could be infected by AcMNPV and express recombinant proteins. Within 24 h of infection with AcMNPV-GFP, the GFP expression was higher than that in Sf21 cells. Furthermore, the infection of RIRI-PA1 cells increased gradually (multiplicity of infection, 10) within 24 h, while in Sf21 cells, the infection only began to increase within 48 h. However, after exposure for 96-168 h, the virus progeny and recombinant protein production of RIRI-PA1 cells was lower than those of Sf21 cells. Western blotting revealed that RIRI-PA1 cells could express recombinant GFP, and the protein expression level positively correlated with the multiplicity of infection. In conclusion, this is the first report that a cell line from P. americana has shown susceptibility to infection from a baculovirus and likewise express recombinant protein. Although the yield of recombinant GFP was not as high as that of Sf21 cells, the results nonetheless showed that RIRI-PA1 had an infection rate advantage in the short term (within 24 h of infection), which is of great value for further development and utilization.

Screening of single-cell clonal lines from Papilio demoleus Linnaeus cell lines for exogenous protein expression and adaptation in serum-free culture

In this paper, four established cell lines derived from newly hatched larvae of Papilio demoleus Linnaeus and 57 single-cell clones derived from the 3 lines were used as test materials. Recombinant β-galactosidase baculovirus AcMNPV-Gal was used to infect the P. demoleus L. cell lines and the single-cell clones, and recombinant protein expression in each cell line was detected and compared. Three clonal cell lines, RIRI-PaDe-1-C1, RIRI-PaDe-2-C6 and RIRI-PaDe-3-C52, which showed significantly higher β-galactosidase expression levels than those of the parental cell lines, were selected. Five types of commercial serum-free media for insect cells, Express Five SFM, Ex-Cell 405, Sf-900III SFM, Sf-900II SFM and HyClone Serum-Free Media, were used to adapt RIRI-PaDe-2-C6 cells and RIRI-PaDe-3-C52 cells to serum-free culture conditions, and the growth characteristics of the cells and the exogenous protein expression characteristics before and after adaptation were compared. The results showed that RIRI-PaDe-2-C6 cells could stably proliferate in Ex-Cell 405, RIRI-PaDe-3-C52 cells could stably proliferate in Express Five SFM and Ex-Cell 405, and the rate of proliferation of and the level of expression of β-galactosidase in RIRI-PaDe-3-C52 cells were significantly increased in Express Five SFM.

Establishment of an embryonic cell line from the American cockroach Periplaneta americana (Blattaria: Blattidae) and a preliminary study of telomerase activity changes during the culturing process

Despite the pest status and medicinal value of the American cockroach Periplaneta americana, few attempts have been made to establish cell lines from this insect owing to the difficulty of culturing Blattarian cells. Here, we describe the establishment of the RIRI-PA1 line from P. americana embryo tissue following primary culture in modified Grace's medium containing 20% fetal bovine serum. RIRI-PA1 was found to primarily consist of attached spindle-shaped and giant cells, which attach themselves to their container. The population-doubling time of 40th-passage cells was approximately 84.8 h. The average chromosome number at the 30th passage was 42, with 40% of cells demonstrating substantial variations, with the highest number of variations of 78 and lowest of 24. The identity of RIRI-PA1 was confirmed by comparing the COI gene of these cells to that of P. americana embryo tissue. Telomerase activity decreased in primary cells after 7 d of culture and 5th-passage cells in comparison to embryo tissues; however, compared to the other cultured cells tested, the telomerase activity significantly increased at the 20th passage. We propose that the stagnation periods and cessation of proliferation observed relate to cellular telomerase activity, but the relationship between insect cell proliferation and telomerase as well as the regulatory mechanism involved remains to be elucidated.

Available Lepidopteran Insect Cell Lines

This chapter lists the known cell lines from Lepidoptera, largely based on previous compilations of insect cell lines published by W. Fred Hink. More than 320 lines from 65 species are listed. The official designation is given for each cell line as well as the species, tissue source, and, when known, the susceptibilities to baculoviruses.

Establishment and characterization of an embryonic cell line from Sarconesiopsis magellanica

Sarconesiopsis magellanica (Le Guillou) (Diptera: Calliphoridae) is a necrophagous fly that is important in both human and veterinary medicines. This insect has been registered in Colombia as a biological indicator in estimating post-mortem interval. Insect cell cultures are an important biotechnological tool for basic and applied studies, and cell cultures derived from S. magellanica embryonic tissues are described in this study. S. magellanica embryonated eggs were taken for tissue explants. These were seeded in L-15, Grace/L-15, Eagle MEM, MM, VP12, MM/VP12, and Schneider culture media. The morphological, cytogenetic, biochemical, and molecular characteristics of the cell cultures were examined. Cell growth was achieved in the L15, Grace/L15, and Schneider culture media, and the confluent monolayers were obtained 8, 10, and 19 days after the embryonated eggs were explanted. However, the Schneider medium was the most efficient to develop the subcultures, and 21 passages have been maintained. The cell morphology of the primary cell cultures was initially heterogeneous, but in the confluent monolayer and in the subcultures there was greater cell morphology uniformity, fibroblastoid types being predominant. Cultured cells had a chromosomal number of 12, and the karyotypic complement consisted of five pairs of somatic chromosomes and one sexual pair. The cell culture isozyme patterns of S. magellanica coincided with adult samples from the same species. The molecular analysis, using RAPD-PCR, demonstrated the authentication of the cell cultures of this fly and their differentiation from other cultures derived from two sand flies species. This cell line is a new in vitro model that will be used in biomedical and biotechnological studies.