It is clear that categorizing semen as either virus free or virus contaminated is not straightforward. For many viruses, e.g., PRRSV, ADV, PCV2, temporal inconsistencies exist among viremia, the presence of virus in semen, and antibodies in serum. In the case of PRRSV, e.g., viremia in adult boars may be of short duration and end before virus shedding in semen ends [59]. Furthermore, in the initial phases of the infection, serologic results will be negative although the virus can be shed in the semen. Finally, boars may remain serologically positive long after the virus is no longer shed in the semen. Because shedding of virus in semen is often intermittent, especially in the later phases of the infection, a negative test result on a semen sample does not preclude subsequent shedding of the virus. A negative result only means that the tested sample of the ejaculate does not contain virus and that the particular ejaculate is likely to be virus free. It does not guarantee absence of contamination in subsequent ejaculates of a boar. Consequently, a negative semen test from a serologically positive boar should be interpreted with caution.
2.2.4. 非典范
猪瘟病毒
Reston ebolavirus is an enveloped RNA virus, classified in the order mononegavirales, family filoviridae. In 2008, severe disease outbreaks suspected to be caused by PRRSV were reported in swine herds in the Philippines. However, detailed diagnostic work revealed that not PRRSV but REBOV had caused the disease and that REBOV-specific antibodies were found in farm workers [30]. The broader significance of this outbreak of REBOV remains to be determined. Subsequent experimental challenge suggested that REBOV infection in pigs may be asymptomatic despite replication of the virus. The mechanism of transmission of REBOV to pigs or between pigs is unknown. Routes of REBOV shedding by pigs are also not known. In nonhuman primate models, REBOV is shed in all body fluids, including semen [29]. Whether REBOV is shed by boars in semen or transmitted to recipient females is unknown. In contrast with REBOV, Zaire ebolavirus has been shown to cause severe lung pathology in 5- to 6-week old pigs leading to respiratory distress [42].
2.2.8.
猪内源性反转录病毒
The presence of viral infections in boars of AI centers and/or the presence of viral pathogens in semen can be assessed using different diagnostic methods such as demonstration of viable virus, nucleic acid of the virus, or antibodies against the virus. From the early 1990s onward, major improvements have been made in terms of increased sensitivity and specificity, simultaneous testing of different pathogens and speed of testing.
5.1. 病毒活性检测
猪精液、猪、人工授精、病毒、回首/检查
2.2 存在猪精液中，未列入OIE名录的病毒
Torque teno virus
猪风疹病毒是一种有包膜RNA病毒，属于副黏病毒科、腮腺炎病毒属。该病毒可导致蓝眼病[80]。此病毒风行于墨西哥，会造成种猪繁殖障碍。传染后，与其他成年动物一样，公猪会罹患严重附睾炎和睾丸炎，性欲减退，凡是不表示临床症状。尚未通过尝试证明该病毒通过精液流传；但是，在接种后长达49天之内，已经从精液、睾丸和生殖道的其他组织中检测到该病毒[39]。近期数据表白，在接种后5至48天可从精液中疏散出该病毒，接种后64至142天可从睾丸和附睾中疏散出该病毒。接种后2到64天，血清中可检测到病毒RNA，接种后142 天，仍可在精液中检测到此病毒[40]。由此证明，猪风疹病毒RNA连续存在于精液中，且长时间传染生殖道。精液检查显示，风行症毒的猪群中，约30%的公猪呈现暂时性或永久性不育、精子浓度下降、形态异常增加、精子的活力和存活能力降低。一些公猪呈现无精症[40]。
未完待续...
5.诊断 Diagnostics
使用带毒精液对母猪进行人工授精，会呈现多种功效。精子质量下降、胚胎早期死亡和/或子宫内膜炎、母猪群中的临床疾病，和/或传染有害病原导致母猪健康程度下降、阻碍病原净化或滋扰监管法子，这些均可能导致受胎率降低[57] 。病原体可穿过透明带直接侵入胚胎，和/或病原体（例如，传染PPV）引起子宫上皮病变，造成胚胎早期死亡[83]。怀胎后的6至7天，透明带作为不行渗透屏障，环绕并掩护胚胎，有助于其制止受诸如PPV，PCV2，ADV和PRRSV等病原体的入侵[65,84,85]。但是，病原体（如ADV）在囊胚期可穿过透明带，导致胚胎更容易传染[84]。
Transmission of viral pathogens by semen to the sow has been clearly proven for CSF virus [10] and PRRSV [61] on experimental infection of boars and for PPV [45], ADV [52], PRRSV [18,21], and PCV2 [41] after inoculation of the virus in the semen. Habu et al. [13] and Guérin and Pozzi [57] reported that Japanese encephalitis virus is easily transmitted to gilts if they are inseminated with contaminated semen, although we did not find a scientific article confirming these statements. Semen contaminated with viral pathogens used for AI does indeed poses a risk for transmission to the recipient sow and by extension the sow herd. This was illustrated by Nathues et al. [81] who described an outbreak of PRRSV in Switzerland after import of boar semen.
Dominiek Maesa,*, Ann Van Sooma, Ruth Appeltanta, Ioannis Arsenakisa, Hans Nauwynckb
Nonclassical swine fever pestiviruses
Interpretation of diagnostic testing
To be continued…
b比利时，梅勒尔贝克，根特大学，兽医学院，病毒学尝试室，免疫与寄生虫学，病毒学科
凡是，在发病时期，精液中存在病毒的可能性最高。但是，现实环境中，不会从临床受影响的公猪中采精，这样仅供降低病毒熏染母猪的风险。无临床症状、呈现轻微临床症状之前，散毒就已经开始，加之严重传染猪只未被发觉，在这些环境下，如果不采纳出格控制法子，会增加病毒流传风险。
猪对非典范猪瘟病毒易感，此类病毒包罗牛病毒性腹泻病毒（BVDV）和界限病病毒；这些RNA病毒会导致牛羊罹患综合疾病。先天传染这些病毒的猪可能会大量散毒。Terpstra和Wenswoort [35]从先天传染及不育公猪的口咽液、尿液和精液中疏散出BVDV。
a比利时，梅勒尔贝克，根特大学，兽医学院，畜群健康与产科学，繁殖科
a Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
Viruses in porcine semen which are not in the OIE list
