[Homozygous CFAP65 mutation induces multiple morphological abnormalities of sperm flagella: A preliminary genetic study].

OBJECTIVE: To search for the possible pathogenic genes for multiple morphological anomalies of sperm flagella (MMAF). METHODS: We performed whole exome sequencing (WES) of a typical case of MMAF and analyzed its possible pathogenic genes. We examined the semen sample from the patient and identified the ultrastructural characteristics of the sperm flagella under the scanning electron and transmission electron microscopes, and analyzed the expression pattern of cilia and flagela-associated protein 65 (CFAP65) in spermatogenesis by immunofluorescence assay. RESULTS: The MMAF patient was found with a homozygous pathogenic mutation of the CFAP65 gene c.2675G>A(p.Trp892*). Scanning electron microscopy showed that the sperm of the patient had typical characteristics of MMAF, that is, without tails or with folded tails, curly tails, short tails or irregular tails. Transmission electron microscopy revealed the loss and disorder of the "9+2" structure in the sperm flagellum, with abnormal assembly of the fibrous sheath, accompanied by loss of central microtubules and dynamin arms. Cellular immunofluorescence assay suggested that the CFAP65 gene was expressed at all levels of mouse germ cells. CONCLUSIONS: The CFAP65 gene is involved in the assembly of the sperm flagellum structure, and its mutation can cause the phenotype of MMAF, leading to male infertility.

Identification and characterization of duck enteritis virus dUTPase gene.

Deoxyuridine triphosphatase (dUTPase) is a ubiquitous and important enzyme that hydrolyzes dUTP to dUMP. Many viruses encode virus-specific dUTPase, which plays an essential role in maintaining the integrity of the viral DNA both by reducing the dUTP levels and by providing the substrate for the thymidylate synthase. A 1344-bp gene of duck enteritis virus (DEV) homologous to herpesviral dUTPase was first reported in this paper. The gene encodes a protein of 477 amino acids, with a predicted molecular mass of 49.7 kDa. Multiple sequence alignment suggested that DEV dUTPase was quite similar to other identified herpesviral dUTPase and functioned as a homotrimer. The five conserved motifs of DEV dUTPase with 3-1-2-4-5 arrangement have been recognized, and the phylogenetic analysis showed that DEV dUTPase was genetically close to the avian herpesvirus. Furthermore, RNA dot blot, western blot, and immunofluorescence analysis indicated that the enzyme was expressed at early and late stages after infection. Immunofluorescence also confirmed that DEV dUTPase localized in the cytoplasm of DEV-infected duck embryo fibroblasts as early as 4 hr postinfection (hpi). Later, the enzyme transferred from cytoplasm to nucleus at 8 hpi, and then reached its expression peak at 12 hpi, both in the cytoplasm and nucleus. The results suggested that the DEV dUTPase gene might be an early viral gene in DEV vitro infection and contribute to ensuring the fidelity of genome replication.

[Replication of duck plague virus in artificially infected ducks detected by in situ hybridization].

Replication of duck plague virus(DPV) in artificially infected ducks were detected by in situ hybridization (ISH) which employed a 37bp oligonucleotide as probe designed according to DPV DNA sequence in GenBank. The results indicated that DPV DNA was detected in liver, intestine and bursa Fabricius at 4 h, in spleen and esophagus at 6h, in thymus at 12h post infection; DPV DNA in lung and kidney was detected only in dead ducks and no positive signal was detected in muscle, heart, cerebrum and pancreas. DPV DNA was distributed in cell nucleus and cytoplasm. Hepatocytes, sinus endodermal cells and Kuffer's cells were the mainly infected cell types in liver. DPV DNA was mainly detected in epithelium of villi, in lamina propria of intestinal villi of duodenum, in stratum spinosum of esophagus, and in epithelium, cortex, medulla of bursa Fabricius. The positive signals were mainly detected in medulla of thymus, lymphocytes and macrophages of spleen. The research suggests that ISH is a direct and specific method in detecting DPV DNA in paraffin sections and it's also a good method for virus diagnosis and DNA location of DPV.

[Studies on porcine reproductive and respiratory syndrome virus morphogenesis in Marc-145 cell and the ultrastructural changes of the infected cells].

Electron microscopy was employed for ultrastructural observation of Marc-145 cells infected with porcine reproductive and respiratory syndrome virus (PRRSV) SC1 strain and studied the virus morphogenesis in infected cells. The results demonstrated that PRRSV was spherical and enveloped. The virion is 45-65 nm in diameter and its nucleocapsid was approximately 25-30 nm. PRRSV entered Marc-145 cells by endocytosis, and replicated in the cytoplasm. The mature viruses were released from infected cells by budding or exocytosis. The main ultrastructural changes of the infected cells were as follows: increased number of cytoplasmic vacuoles, dilated endoplasmic reticulum, mitochondria underwent hyperplasia with its ridges swollen, sloughed, and eventually vacuolated. Typical apoptosis was also observed in the infected Marc-145 cells, which included microvilli sloughing off the cell, appearance of apoptotic bodies and cell fragmentation.

Electron microscopic studies of the morphogenesis of duck enteritis virus.

The morphogenesis of duck enteritis virus (DEV) and distribution in vivo were observed by electron microscopy after ducks were infected experimentally with DEV virulent strain. The investigation showed that a few typical herpesvirus virions and nucleocapsids were first observed in the spleen, thymus, and bursa of Fabricius (BF), and many nucleocapsids, mature viruses, and viral inclusion bodies could be found in the nucleus and cytoplasm of infected liver, small intestine, spleen, thymus, and BF when the ducks died. Nucleocapsids assembled both in nucleus and cytoplasm and could be divided into four different types according to their structures. Typical herpesvirus, light particles (L-particles), and virions without tegument could be observed at the same time. With the replication, assembly, and maturation of the viruses, intracytoplasmic and intranuclear inclusion bodies, electron-density particles, microtubules, hollow tubes, and coated electron-density bodies were observed in infected cells.