Experimental vertical transmission of covert mortality nodavirus in Exopalaemon carinicauda.

Viral covert mortality disease (VCMD) has caused serious losses to shrimp aquaculture in China in recent years and the ridgetail white prawn Exopalaemon carinicauda has been suspected to be one important factor in perpetuating the high prevalence of covert mortality nodavirus (CMNV) infections due to its perennial presence in shrimp farming ponds and water from natural habitats. Experiments were carried out to determine the possibility of vertical transmission of CMNV in E. carinicauda in this study. CMNV infection in gonads, fertilized eggs and larvae was investigated by using the methods of reverse transcription nested PCR (nRT-PCR), in situ hybrization (ISH) and transmission electron microscopy (TEM). The ovarian tissue and testis tissue of artificially infected parental E. carinicauda were proved to be CMNV-positive by nRT-PCR. Fertilized eggs were also found to be CMNV-positive by nRT-PCR whether the fertilized eggs originated from the CMNV-positive female broodstock mated with the CMNV-negative male broodstock, or they originated from the CMNV-negative female broodstock mated with the CMNV-positive males. The results of ISH indicated that the positive signals were evident in the oocytes within ovarian tissue and nauplii. By TEM analysis, CMNV virions were observed in oogonia, oocytes, spermatocytes, fertilized eggs and nauplii. The presence of CMNV in fertilized eggs and larvae indicates that CMNV can transmit vertically via sperm and oocytes in E. carinicauda, which highlights the high probability of vertical transmission of CMNV in the main species of cultured shrimp and prawns.

Zika virus infection damages the testes in mice.

Infection of pregnant women with Zika virus (ZIKV) can cause congenital malformations including microcephaly, which has focused global attention on this emerging pathogen. In addition to transmission by mosquitoes, ZIKV can be detected in the seminal fluid of affected males for extended periods of time and transmitted sexually. Here, using a mouse-adapted African ZIKV strain (Dakar 41519), we evaluated the consequences of infection in the male reproductive tract of mice. We observed persistence of ZIKV, but not the closely related dengue virus (DENV), in the testis and epididymis of male mice, and this was associated with tissue injury that caused diminished testosterone and inhibin B levels and oligospermia. ZIKV preferentially infected spermatogonia, primary spermatocytes and Sertoli cells in the testis, resulting in cell death and destruction of the seminiferous tubules. Less damage was caused by a contemporary Asian ZIKV strain (H/PF/2013), in part because this virus replicates less efficiently in mice. The extent to which these observations in mice translate to humans remains unclear, but longitudinal studies of sperm function and viability in ZIKV-infected humans seem warranted.

[Effect of herpes simplex virus on spermatogenesis].

To investigate the effect of Herpes Simplex virus (HSV) on spermatogenesis, HSV in ejaculate was detected by a rapid cultural method in 268 infertile males and 47 healthy ones. The number of mobile spermatozoa in HSV infected samples was less than in non-infected samples (21 mln/mlversus 40 mln/ml, p = 0.0001). The relative number of morphologically normal gametes was 13% versus 19% (p = 0.002), respectively. The quantitative karyological test discovered that males with HSV-infected ejaculate have more degenerating sex cells while in high virus contamination (more than 10 virus particles in 1 ml) the number of spermatides and spermatocytes of the 1 order at diploten stage is low. Organic testicular culture was used for more detailed study of pathogenetic mechanisms of HSV impact on spermatogenesis. Testicular explants infection was associated with reduction in the number of spermatogones, spermatocytes and spermatides on culturing week 2. The above findings reveal some pathogenetic mechanisms underling fertility disorders in males with HSV infection: a gametotoxic effect of the virus reducing populations of spermatogones, spermatocytes and spermatide; affected mobility and morphological characteristics of spermatozoa. Detection of the mechanisms of HSV action on spermatogenesis opens a perspective of antivirus drug administration in combined treatment of male infertility.

Deletion of the pluripotency-associated Tex19.1 gene causes activation of endogenous retroviruses and defective spermatogenesis in mice.

As genetic information is transmitted through successive generations, it passes between pluripotent cells in the early embryo and germ cells in the developing foetus and adult animal. Tex19.1 encodes a protein of unknown function, whose expression is restricted to germ cells and pluripotent cells. During male spermatogenesis, Tex19.1 expression is highest in mitotic spermatogonia and diminishes as these cells differentiate and progress through meiosis. In pluripotent stem cells, Tex19.1 expression is also downregulated upon differentiation. However, it is not clear whether Tex19.1 has an essential function in germ cells or pluripotent stem cells, or what that function might be. To analyse the potential role of Tex19.1 in pluripotency or germ cell function we have generated Tex19.1(-/-) knockout mice and analysed the Tex19.1(-/-) mutant phenotype. Adult Tex19.1(-/-) knockout males exhibit impaired spermatogenesis. Immunostaining and histological analysis revealed defects in meiotic chromosome synapsis, the persistence of DNA double-strand breaks during meiosis, and a loss of post-meiotic germ cells in the testis. Furthermore, expression of a class of endogenous retroviruses is upregulated during meiosis in the Tex19.1(-/-) testes. Increased transposition of endogenous retroviruses in the germline of Tex19.1(-/-) mutant mice, and the concomitant increase in DNA damage, may be sufficient to disrupt the normal processes of recombination and chromosome synapsis during meiosis and cause defects in spermatogenesis. Our results suggest that Tex19.1 is part of a specialised mechanism that operates in the germline to repress transposable genetic elements and maintain genomic stability through successive generations.

Localization of classical swine fever virus in male gonads during subclinical infection.

In an experiment using ten boars, the distribution of classical swine fever virus (CSFV) was determined in the male reproductive tract by in situ hybridization over a period of 120 days after intranasal inoculation. CSFV was detected in the testicular tissue of infected boars. Viral nucleic acid was localized to spermatogonia, spermatocytes and spermatids but was not detected in the epithelia of the prostate, epididymis or bulbourethral gland. Sections from control, CSFV-negative, pigs showed no hybridization signals for CSFV. The demonstration that CSFV infects the spermatogonia (and their progeny) suggests that this may serve as a primary reservoir for the venereal spread of CSFV.

Production of the chemokines monocyte chemotactic protein-1, regulated on activation normal T cell expressed and secreted protein, growth-related oncogene, and interferon-gamma-inducible protein-10 is induced by the Sendai virus in human and rat testicular cells.

Several viruses infect the testis, inducing inflammation, which may lead to infertility. In this study we investigated the production in rat and human testicular cells exposed to the Sendai virus of several chemokines that play a major role in inflammatory processes. Exposure of rat testicular macrophages and Sertoli, Leydig, and peritubular cells to the Sendai virus led to the production of mRNA and protein for monocyte chemotactic protein-1 (MCP-1), regulated on activation normal T cell expressed and secreted protein, growth-related oncogene-alpha, and interferon-gamma-inducible protein-10. In rat peritubular cells exposed to the Sendai virus, MCP-1 production was time and dose dependent. In contrast, rat germ cells did not produce these chemokines. Chemokine synthesis was detected in human Leydig cells exposed to the Sendai virus, but not in human total germ cells, suggesting that rats and humans display similar responses in terms of chemokine production. MCP-1, regulated on activation normal T cell expressed and secreted protein, growth-related oncogene-alpha, and interferon-gamma-inducible protein-10 have been reported to be chemoattractants for a large variety of leukocytes. The ability of the Sendai virus to induce chemokine production in somatic cells (mostly peritubular and Leydig cells) may therefore increase the recruitment of leukocytes to sites of infection.

A Drosophila model of HIV-Tat-related pathogenicity.

To analyze the mechanism of Tat-mediated HIV pathogenicity, we produced a Drosophila melanogaster strain transgenic for HIV-tat gene and induced the expression of the protein during Drosophila development. By in vitro and in vivo experiments, we demonstrated that Tat specifically binds to tubulin via the MAP-binding domain of tubulin, and that this interaction delays the polymerization of tubulin and induces a premature stop to microtubule-dependent cytoplasmic streaming. The delay in the polymerization of microtubules, the tracks for the transport of the axes determinants, alters the positioning of the dorso-ventral axis as shown by the mislocalization of Gurken and Kinesin in oocyte of Drosophila after Tat induction. These results validate the use of Drosophila as a tool to study the molecular mechanism of viral gene products and suggest that Tat-tubulin interaction is responsible for neurodegenerative diseases associated with AIDS.

Germ cell expression of an isolated human endogenous retroviral long terminal repeat of the HERV-K/HTDV family in transgenic mice.

In contrast to most other human endogenous retroviral families, various HERV-K members have open reading frames that code for functional viral proteins which can form noninfectious particles in some germ cell tumors. The HERV-K viral genes are highly transcribed in germ cell tumors but are transcribed to lower or undetectable levels in most other tissue and tumor types. To further analyze the expression patterns of these proviruses, long terminal repeats (LTRs) were isolated from the human genome and used in reporter gene assays. Expression of some HERV-K LTRs was found to be high in human and murine germ cell tumors (testicular teratocarcinomas) and low in non-germ-cell tumors. Furthermore, upon differentiation of a teratocarcinoma cell line, the expression of an active LTR dropped dramatically, suggesting developmental regulation of these proviral LTRs. Transgenic mice harboring an active LTR driving lacZ expression were generated and analyzed. Adult mouse testes showed the highest levels of expression, and the transgene staining appeared to be restricted primarily to the more undifferentiated spermatocytes. Most other tissues analyzed revealed very low or undetectable levels of expression both by reverse transcription-PCR and by Northern blot analysis. Whether the restricted expression of HERV-K in germ cells and in germ cell-derived tumors is of significant importance during development or tumorigenesis remains to be elucidated. Germ line expression of these viruses would allow for their expansion and movement, while somatic repression would ensure limited insertional mutagenesis and misexpression in an individual.